mybatis

DataSource dataSource = YamlShardingDataSourceFactory.createDataSource(yamlFile);
String sql = "SELECT i.* FROM t_order o JOIN t_order_item i ON o.order_id=i.order_id WHERE o.user_id=? AND o.order_id=?";
try (
    Connection conn = dataSource.getConnection();
    PreparedStatement preparedStatement = conn.prepareStatement(sql)) {
    preparedStatement.setInt(1, 10);
    preparedStatement.setInt(2, 1001);
    try (ResultSet rs = preparedStatement.executeQuery()) {
        while(rs.next()) {
            System.out.println(rs.getInt(1));
            System.out.println(rs.getInt(2));
        }
    }
}

使用xml初始化SqlSessionFactory
String resource = "mybatis.xml";
InputStream inputStream  = Resources.getResourceAsStream(resource);
//解析mybatis配置文件，主要解析mapperElement(root.evalNode("mappers"));
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

（不使用xml初始化SqlSessionFactory
DataSource dataSource = BlogDataSourceFactory.getBlogDataSource();
TransactionFactory transactionFactory = new JdbcTransactionFactory();
Environment environment = new Environment("development", transactionFactory, dataSource);
Configuration configuration = new Configuration(environment);
configuration.addMapper(BlogMapper.class);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(configuration);
）

  
SqlSession sqlSession = sqlSessionFactory.openSession();
动态代理xxxMapper，执行xxxMapper函数的时候发送sql命令
xxxMapper mapper = session.getMapper(xxxMapper.class);
mapper.select();



public final class Environment {
  private final String id;
  private final TransactionFactory transactionFactory;
  private final DataSource dataSource;
}

xml配置enviroment，根据type属性，反射实例化TransactionFactory、DataSourceFactory
<environments default="development">
  <environment id="development">
    <transactionManager type="JDBC">
      <property name="..." value="..."/>
    </transactionManager>
    <dataSource type="POOLED">
      <property name="driver" value="${driver}"/>
      <property name="url" value="${url}"/>
      <property name="username" value="${username}"/>
      <property name="password" value="${password}"/>
    </dataSource>
  </environment>
</environments>
  
  private void environmentsElement(XNode context) throws Exception {
    if (context != null) {
      if (environment == null) {
        environment = context.getStringAttribute("default");
      }
      for (XNode child : context.getChildren()) {
        String id = child.getStringAttribute("id");
        if (isSpecifiedEnvironment(id)) {
          TransactionFactory txFactory = transactionManagerElement(child.evalNode("transactionManager"));
          DataSourceFactory dsFactory = dataSourceElement(child.evalNode("dataSource"));
          DataSource dataSource = dsFactory.getDataSource();
          Environment.Builder environmentBuilder = new Environment.Builder(id)
              .transactionFactory(txFactory)
              .dataSource(dataSource);
          configuration.setEnvironment(environmentBuilder.build());
        }
      }
    }
  }

private TransactionFactory transactionManagerElement(XNode context) throws Exception {
    if (context != null) {
      String type = context.getStringAttribute("type");
      Properties props = context.getChildrenAsProperties();
      TransactionFactory factory = (TransactionFactory) resolveClass(type).getDeclaredConstructor().newInstance();
      factory.setProperties(props);
      return factory;
    }
    throw new BuilderException("Environment declaration requires a TransactionFactory.");
  }

  private DataSourceFactory dataSourceElement(XNode context) throws Exception {
    if (context != null) {
      String type = context.getStringAttribute("type");
      Properties props = context.getChildrenAsProperties();
      DataSourceFactory factory = (DataSourceFactory) resolveClass(type).getDeclaredConstructor().newInstance();
      factory.setProperties(props);
      return factory;
    }
    throw new BuilderException("Environment declaration requires a DataSourceFactory.");
  }


别名池
 	typeAliasRegistry.registerAlias("JDBC", JdbcTransactionFactory.class);
    typeAliasRegistry.registerAlias("POOLED", PooledDataSourceFactory.class);

public final class MappedStatement {

  private String resource;
  private Configuration configuration;
  private String id;
  private Integer fetchSize;
  private Integer timeout;
  private StatementType statementType;
  private ResultSetType resultSetType;
  // 能根据输入参数，生成发送给数据库的sql
  private SqlSource sqlSource;
  private Cache cache;
  private ParameterMap parameterMap;
  private List<ResultMap> resultMaps;
  private boolean flushCacheRequired;
  private boolean useCache;
  private boolean resultOrdered;
  private SqlCommandType sqlCommandType;
  private KeyGenerator keyGenerator;
  private String[] keyProperties;
  private String[] keyColumns;
  private boolean hasNestedResultMaps;
  private String databaseId;
  private Log statementLog;
  private LanguageDriver lang;
  private String[] resultSets;
}

public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
  try {
    if (Object.class.equals(method.getDeclaringClass())) {
      return method.invoke(this, args);
    } else if (isDefaultMethod(method)) {
      return invokeDefaultMethod(proxy, method, args);
    }
  } catch (Throwable t) {
    throw ExceptionUtil.unwrapThrowable(t);
  }
  // 增强方法
  final MapperMethod mapperMethod = cachedMapperMethod(method);
  // 执行方法
  return mapperMethod.execute(sqlSession, args);
}

private MapperMethod cachedMapperMethod(Method method) {
  MapperMethod mapperMethod = methodCache.get(method);
  if (mapperMethod == null) {
    mapperMethod = new MapperMethod(mapperInterface, method, sqlSession.getConfiguration());
    methodCache.put(method, mapperMethod);
  }
  return mapperMethod;
}

org.apache.ibatis.binding.MapperMethod#MapperMethod->
  
  public MapperMethod(Class<?> mapperInterface, Method method, Configuration config) {
    // 找到对应的sql语句
    this.command = new SqlCommand(config, mapperInterface, method);
    this.method = new MethodSignature(config, mapperInterface, method);
  }

		public SqlCommand(Configuration configuration, Class<?> mapperInterface, Method method) {
      String statementName = mapperInterface.getName() + "." + method.getName();
      MappedStatement ms = null;
      if (configuration.hasStatement(statementName)) {
        //找到对应的statement
        ms = configuration.getMappedStatement(statementName); 
      } else if (!mapperInterface.equals(method.getDeclaringClass())) { // issue #35
        String parentStatementName = method.getDeclaringClass().getName() + "." + method.getName();
        if (configuration.hasStatement(parentStatementName)) {
          ms = configuration.getMappedStatement(parentStatementName);
        }
      }
      if (ms == null) {
        if(method.getAnnotation(Flush.class) != null){
          name = null;
          type = SqlCommandType.FLUSH;
        } else {
          throw new BindingException("Invalid bound statement (not found): " + statementName);
        }
      } else {
        name = ms.getId();
        type = ms.getSqlCommandType();
        if (type == SqlCommandType.UNKNOWN) {
          throw new BindingException("Unknown execution method for: " + name);
        }
      }
    }


    public MethodSignature(Configuration configuration, Class<?> mapperInterface, Method method) {
      Type resolvedReturnType = TypeParameterResolver.resolveReturnType(method, mapperInterface);
      if (resolvedReturnType instanceof Class<?>) {
        this.returnType = (Class<?>) resolvedReturnType;
      } else if (resolvedReturnType instanceof ParameterizedType) {
        this.returnType = (Class<?>) ((ParameterizedType) resolvedReturnType).getRawType();
      } else {
        this.returnType = method.getReturnType();
      }
      this.returnsVoid = void.class.equals(this.returnType);
      this.returnsMany = (configuration.getObjectFactory().isCollection(this.returnType) || this.returnType.isArray());
      this.returnsCursor = Cursor.class.equals(this.returnType);
      this.mapKey = getMapKey(method);
      this.returnsMap = (this.mapKey != null);
      this.rowBoundsIndex = getUniqueParamIndex(method, RowBounds.class);
      this.resultHandlerIndex = getUniqueParamIndex(method, ResultHandler.class);
      this.paramNameResolver = new ParamNameResolver(configuration, method);
    }

普通transaction
public class JdbcTransaction implements Transaction 
  
spring管理的transaction
public class SpringManagedTransaction implements Transaction 	

/**
 * The primary Java interface for working with MyBatis.
 * Through this interface you can execute commands, get mappers and manage transactions.
 *
 * @author Clinton Begin
 */
public interface SqlSession extends Closeable {

  /**
   * Retrieve a single row mapped from the statement key.
   * @param <T> the returned object type
   * @param statement
   * @return Mapped object
   */
  <T> T selectOne(String statement);

  /**
   * Retrieve a single row mapped from the statement key and parameter.
   * @param <T> the returned object type
   * @param statement Unique identifier matching the statement to use.
   * @param parameter A parameter object to pass to the statement.
   * @return Mapped object
   */
  <T> T selectOne(String statement, Object parameter);

  /**
   * Retrieve a list of mapped objects from the statement key and parameter.
   * @param <E> the returned list element type
   * @param statement Unique identifier matching the statement to use.
   * @return List of mapped object
   */
  <E> List<E> selectList(String statement);

  /**
   * Retrieve a list of mapped objects from the statement key and parameter.
   * @param <E> the returned list element type
   * @param statement Unique identifier matching the statement to use.
   * @param parameter A parameter object to pass to the statement.
   * @return List of mapped object
   */
  <E> List<E> selectList(String statement, Object parameter);

  /**
   * Retrieve a list of mapped objects from the statement key and parameter,
   * within the specified row bounds.
   * @param <E> the returned list element type
   * @param statement Unique identifier matching the statement to use.
   * @param parameter A parameter object to pass to the statement.
   * @param rowBounds  Bounds to limit object retrieval
   * @return List of mapped object
   */
  <E> List<E> selectList(String statement, Object parameter, RowBounds rowBounds);

  /**
   * The selectMap is a special case in that it is designed to convert a list
   * of results into a Map based on one of the properties in the resulting
   * objects.
   * Eg. Return a of Map[Integer,Author] for selectMap("selectAuthors","id")
   * @param <K> the returned Map keys type
   * @param <V> the returned Map values type
   * @param statement Unique identifier matching the statement to use.
   * @param mapKey The property to use as key for each value in the list.
   * @return Map containing key pair data.
   */
  <K, V> Map<K, V> selectMap(String statement, String mapKey);

  /**
   * The selectMap is a special case in that it is designed to convert a list
   * of results into a Map based on one of the properties in the resulting
   * objects.
   * @param <K> the returned Map keys type
   * @param <V> the returned Map values type
   * @param statement Unique identifier matching the statement to use.
   * @param parameter A parameter object to pass to the statement.
   * @param mapKey The property to use as key for each value in the list.
   * @return Map containing key pair data.
   */
  <K, V> Map<K, V> selectMap(String statement, Object parameter, String mapKey);

  /**
   * The selectMap is a special case in that it is designed to convert a list
   * of results into a Map based on one of the properties in the resulting
   * objects.
   * @param <K> the returned Map keys type
   * @param <V> the returned Map values type
   * @param statement Unique identifier matching the statement to use.
   * @param parameter A parameter object to pass to the statement.
   * @param mapKey The property to use as key for each value in the list.
   * @param rowBounds  Bounds to limit object retrieval
   * @return Map containing key pair data.
   */
  <K, V> Map<K, V> selectMap(String statement, Object parameter, String mapKey, RowBounds rowBounds);

  /**
   * A Cursor offers the same results as a List, except it fetches data lazily using an Iterator.
   * @param <T> the returned cursor element type.
   * @param statement Unique identifier matching the statement to use.
   * @return Cursor of mapped objects
   */
  <T> Cursor<T> selectCursor(String statement);

  /**
   * A Cursor offers the same results as a List, except it fetches data lazily using an Iterator.
   * @param <T> the returned cursor element type.
   * @param statement Unique identifier matching the statement to use.
   * @param parameter A parameter object to pass to the statement.
   * @return Cursor of mapped objects
   */
  <T> Cursor<T> selectCursor(String statement, Object parameter);

  /**
   * A Cursor offers the same results as a List, except it fetches data lazily using an Iterator.
   * @param <T> the returned cursor element type.
   * @param statement Unique identifier matching the statement to use.
   * @param parameter A parameter object to pass to the statement.
   * @param rowBounds  Bounds to limit object retrieval
   * @return Cursor of mapped objects
   */
  <T> Cursor<T> selectCursor(String statement, Object parameter, RowBounds rowBounds);

  /**
   * Retrieve a single row mapped from the statement key and parameter
   * using a {@code ResultHandler}.
   * @param statement Unique identifier matching the statement to use.
   * @param parameter A parameter object to pass to the statement.
   * @param handler ResultHandler that will handle each retrieved row
   */
  void select(String statement, Object parameter, ResultHandler handler);

  /**
   * Retrieve a single row mapped from the statement
   * using a {@code ResultHandler}.
   * @param statement Unique identifier matching the statement to use.
   * @param handler ResultHandler that will handle each retrieved row
   */
  void select(String statement, ResultHandler handler);

  /**
   * Retrieve a single row mapped from the statement key and parameter
   * using a {@code ResultHandler} and {@code RowBounds}.
   * @param statement Unique identifier matching the statement to use.
   * @param rowBounds RowBound instance to limit the query results
   * @param handler ResultHandler that will handle each retrieved row
   */
  void select(String statement, Object parameter, RowBounds rowBounds, ResultHandler handler);

  /**
   * Execute an insert statement.
   * @param statement Unique identifier matching the statement to execute.
   * @return int The number of rows affected by the insert.
   */
  int insert(String statement);

  /**
   * Execute an insert statement with the given parameter object. Any generated
   * autoincrement values or selectKey entries will modify the given parameter
   * object properties. Only the number of rows affected will be returned.
   * @param statement Unique identifier matching the statement to execute.
   * @param parameter A parameter object to pass to the statement.
   * @return int The number of rows affected by the insert.
   */
  int insert(String statement, Object parameter);

  /**
   * Execute an update statement. The number of rows affected will be returned.
   * @param statement Unique identifier matching the statement to execute.
   * @return int The number of rows affected by the update.
   */
  int update(String statement);

  /**
   * Execute an update statement. The number of rows affected will be returned.
   * @param statement Unique identifier matching the statement to execute.
   * @param parameter A parameter object to pass to the statement.
   * @return int The number of rows affected by the update.
   */
  int update(String statement, Object parameter);

  /**
   * Execute a delete statement. The number of rows affected will be returned.
   * @param statement Unique identifier matching the statement to execute.
   * @return int The number of rows affected by the delete.
   */
  int delete(String statement);

  /**
   * Execute a delete statement. The number of rows affected will be returned.
   * @param statement Unique identifier matching the statement to execute.
   * @param parameter A parameter object to pass to the statement.
   * @return int The number of rows affected by the delete.
   */
  int delete(String statement, Object parameter);

  /**
   * Flushes batch statements and commits database connection.
   * Note that database connection will not be committed if no updates/deletes/inserts were called.
   * To force the commit call {@link SqlSession#commit(boolean)}
   */
  void commit();

  /**
   * Flushes batch statements and commits database connection.
   * @param force forces connection commit
   */
  void commit(boolean force);

  /**
   * Discards pending batch statements and rolls database connection back.
   * Note that database connection will not be rolled back if no updates/deletes/inserts were called.
   * To force the rollback call {@link SqlSession#rollback(boolean)}
   */
  void rollback();

  /**
   * Discards pending batch statements and rolls database connection back.
   * Note that database connection will not be rolled back if no updates/deletes/inserts were called.
   * @param force forces connection rollback
   */
  void rollback(boolean force);

  /**
   * Flushes batch statements.
   * @return BatchResult list of updated records
   * @since 3.0.6
   */
  List<BatchResult> flushStatements();

  /**
   * Closes the session.
   */
  @Override
  void close();

  /**
   * Clears local session cache.
   */
  void clearCache();

  /**
   * Retrieves current configuration.
   * @return Configuration
   */
  Configuration getConfiguration();

  /**
   * Retrieves a mapper.
   * @param <T> the mapper type
   * @param type Mapper interface class
   * @return a mapper bound to this SqlSession
   */
  <T> T getMapper(Class<T> type);

  /**
   * Retrieves inner database connection.
   * @return Connection
   */
  Connection getConnection();
}

这个接口能执行sql命令、获取代理后的mapper、管理事务
   

private SqlSession openSessionFromDataSource(ExecutorType execType, TransactionIsolationLevel level, boolean autoCommit) {
    ............
    final Executor executor = configuration.newExecutor(tx, execType);     
    return new DefaultSqlSession(configuration, executor, autoCommit);
}

  public <T> T getMapper(Class<T> type, SqlSession sqlSession) {
    final MapperProxyFactory<T> mapperProxyFactory = (MapperProxyFactory<T>) knownMappers.get(type);
    if (mapperProxyFactory == null) {
      throw new BindingException("Type " + type + " is not known to the MapperRegistry.");
    }
    try {
      return mapperProxyFactory.newInstance(sqlSession);
    } catch (Exception e) {
      throw new BindingException("Error getting mapper instance. Cause: " + e, e);
    }
  }

public class MapperProxyFactory<T> {

  private final Class<T> mapperInterface;
  private final Map<Method, MapperMethodInvoker> methodCache = new ConcurrentHashMap<>();

  public MapperProxyFactory(Class<T> mapperInterface) {
    this.mapperInterface = mapperInterface;
  }

  public Class<T> getMapperInterface() {
    return mapperInterface;
  }

  public Map<Method, MapperMethodInvoker> getMethodCache() {
    return methodCache;
  }

  @SuppressWarnings("unchecked")
  protected T newInstance(MapperProxy<T> mapperProxy) {
    return (T) Proxy.newProxyInstance(mapperInterface.getClassLoader(), new Class[] { mapperInterface }, mapperProxy);
  }

  public T newInstance(SqlSession sqlSession) {
    final MapperProxy<T> mapperProxy = new MapperProxy<>(sqlSession, mapperInterface, methodCache);
    return newInstance(mapperProxy);
  }

}

public enum ExecutorType {
  SIMPLE, REUSE, BATCH
}
默认SIMPLE

org.apache.ibatis.executor.SimpleExecutor#doQuery

  public <E> List<E> doQuery(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {
    Statement stmt = null;
    try {
      Configuration configuration = ms.getConfiguration();
			// 生成statementHandler
      StatementHandler handler = configuration.newStatementHandler(wrapper, ms, parameter, rowBounds, resultHandler, boundSql);
      // 用handler把参数拼接到sql
      stmt = prepareStatement(handler, ms.getStatementLog());
      return handler.<E>query(stmt, resultHandler);
    } finally {
      closeStatement(stmt);
    }
  }

StatementHandler handler = configuration.newStatementHandler(wrapper, ms, parameter, rowBounds, resultHandler, boundSql);

// 生成statementHandler  
public StatementHandler newStatementHandler(Executor executor, MappedStatement mappedStatement, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) {
    StatementHandler statementHandler = new RoutingStatementHandler(executor, mappedStatement, parameterObject, rowBounds, resultHandler, boundSql);
    // 把插件放入statementHandler
    statementHandler = (StatementHandler) interceptorChain.pluginAll(statementHandler);
    return statementHandler;
  }
  
// 生成statementHandler代理
public RoutingStatementHandler(Executor executor, MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) {

    switch (ms.getStatementType()) {
      case STATEMENT:
        delegate = new SimpleStatementHandler(executor, ms, parameter, rowBounds, resultHandler, boundSql);
        break;
      case PREPARED:
        delegate = new PreparedStatementHandler(executor, ms, parameter, rowBounds, resultHandler, boundSql);
        break;
      case CALLABLE:
        delegate = new CallableStatementHandler(executor, ms, parameter, rowBounds, resultHandler, boundSql);
        break;
      default:
        throw new ExecutorException("Unknown statement type: " + ms.getStatementType());
    }

  }


  public SimpleStatementHandler(Executor executor, MappedStatement mappedStatement, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) {
    super(executor, mappedStatement, parameter, rowBounds, resultHandler, boundSql);
  }

 protected BaseStatementHandler(Executor executor, MappedStatement mappedStatement, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) {
    this.configuration = mappedStatement.getConfiguration();
    this.executor = executor;
    this.mappedStatement = mappedStatement;
    this.rowBounds = rowBounds;

    this.typeHandlerRegistry = configuration.getTypeHandlerRegistry();
    this.objectFactory = configuration.getObjectFactory();

    if (boundSql == null) { // issue #435, get the key before calculating the statement
      generateKeys(parameterObject);
      boundSql = mappedStatement.getBoundSql(parameterObject);
    }

    this.boundSql = boundSql;

   	// 实例化parameterHandler
    this.parameterHandler = configuration.newParameterHandler(mappedStatement, parameterObject, boundSql);
   	// 实例化resultSetHandler
    this.resultSetHandler = configuration.newResultSetHandler(executor, mappedStatement, rowBounds, parameterHandler, resultHandler, boundSql);
  }

  public ParameterHandler newParameterHandler(MappedStatement mappedStatement, Object parameterObject, BoundSql boundSql) {
    ParameterHandler parameterHandler = mappedStatement.getLang().createParameterHandler(mappedStatement, parameterObject, boundSql);
    // 将插件放入parameterHandler
    parameterHandler = (ParameterHandler) interceptorChain.pluginAll(parameterHandler);
    return parameterHandler;
  }


  public ResultSetHandler newResultSetHandler(Executor executor, MappedStatement mappedStatement, RowBounds rowBounds, ParameterHandler parameterHandler,
      ResultHandler resultHandler, BoundSql boundSql) {
    ResultSetHandler resultSetHandler = new DefaultResultSetHandler(executor, mappedStatement, parameterHandler, resultHandler, boundSql, rowBounds);
    // 将插件放入resultSetHandler
    resultSetHandler = (ResultSetHandler) interceptorChain.pluginAll(resultSetHandler);
    return resultSetHandler;
  }


插件还能放入executor
  
  public Executor newExecutor(Transaction transaction, ExecutorType executorType) {
    executorType = executorType == null ? defaultExecutorType : executorType;
    executorType = executorType == null ? ExecutorType.SIMPLE : executorType;
    Executor executor;
    if (ExecutorType.BATCH == executorType) {
      executor = new BatchExecutor(this, transaction);
    } else if (ExecutorType.REUSE == executorType) {
      executor = new ReuseExecutor(this, transaction);
    } else {
      executor = new SimpleExecutor(this, transaction);
    }
    if (cacheEnabled) {
      executor = new CachingExecutor(executor);
    }
  	// 将插件放入executor
    executor = (Executor) interceptorChain.pluginAll(executor);
    return executor;
  }

	// 用handler把参数拼接到sql
  private Statement prepareStatement(StatementHandler handler, Log statementLog) throws SQLException {
    Statement stmt;
    Connection connection = getConnection(statementLog);
    stmt = handler.prepare(connection, transaction.getTimeout());
    handler.parameterize(stmt);
    return stmt;
  }

  public void parameterize(Statement statement) throws SQLException {
    delegate.parameterize(statement);
  }

  public void parameterize(Statement statement) throws SQLException {
    parameterHandler.setParameters((PreparedStatement) statement);
  }

org.apache.ibatis.scripting.defaults.DefaultParameterHandler#setParameters

1. 根据xml或者无xml初始化SqlSessionFactory
	SqlSessionFactoryBuilder().build
2. 打开SqlSession对象 
	sqlSessionFactory.openSession()
3. 动态代理mapper
  sqlSession.getMapper()
4. 执行代理后的对象mapperProxy的invoke
  sqlSession.select/update
5. BaseExecutor/CachingExecutor(BaseExecutor的代理)
  Executor执行query/queryFromDatabase
6. 初始化prepareStatement并给#{}赋值 
  SimpleExecutor.doQuery
7. 执行sql语句 
  StatementHandler.query
8. 封装结果集 
  ResultHandler handleResultSets	

  private final SortedMap<Integer, String> names;

	public ParamNameResolver(Configuration config, Method method) {
    final Class<?>[] paramTypes = method.getParameterTypes();
    final Annotation[][] paramAnnotations = method.getParameterAnnotations();
    final SortedMap<Integer, String> map = new TreeMap<>();
    int paramCount = paramAnnotations.length;
    // get names from @Param annotations
    for (int paramIndex = 0; paramIndex < paramCount; paramIndex++) {
      if (isSpecialParameter(paramTypes[paramIndex])) {
        // skip special parameters
        continue;
      }
      String name = null;
      for (Annotation annotation : paramAnnotations[paramIndex]) {
        if (annotation instanceof Param) {
          hasParamAnnotation = true;
          name = ((Param) annotation).value();
          break;
        }
      }
      if (name == null) {
        // @Param was not specified.
        if (config.isUseActualParamName()) {
          name = getActualParamName(method, paramIndex);
        }
        if (name == null) {
          // use the parameter index as the name ("0", "1", ...)
          // gcode issue #71
          name = String.valueOf(map.size());
        }
      }
      map.put(paramIndex, name);
    }
    names = Collections.unmodifiableSortedMap(map);
  }

public final class MappedStatement {

  private String resource;
  private Configuration configuration;
  private String id;
  private Integer fetchSize;
  private Integer timeout;
  private StatementType statementType;
  private ResultSetType resultSetType;
  private SqlSource sqlSource;
  private Cache cache;
  private ParameterMap parameterMap;
  private List<ResultMap> resultMaps;
  private boolean flushCacheRequired;
  private boolean useCache;
  private boolean resultOrdered;
  private SqlCommandType sqlCommandType;
  private KeyGenerator keyGenerator;
  private String[] keyProperties;
  private String[] keyColumns;
  private boolean hasNestedResultMaps;
  private String databaseId;
  private Log statementLog;
  private LanguageDriver lang;
  private String[] resultSets;

  MappedStatement() {
    // constructor disabled
  }
}

public <E> List<E> doQuery(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {
  Statement stmt = null;
  try {
    Configuration configuration = ms.getConfiguration();
    StatementHandler handler = configuration.newStatementHandler(wrapper, ms, parameter, rowBounds, resultHandler, boundSql);
    stmt = prepareStatement(handler, ms.getStatementLog());
    return handler.query(stmt, resultHandler);
  } finally {
    closeStatement(stmt);
  }
}

/**
 * Wraps a database connection.
 * Handles the connection lifecycle that comprises: its creation, preparation, commit/rollback and close.
 *
 * @author Clinton Begin
 */

/**
 * {@code SpringManagedTransaction} handles the lifecycle of a JDBC connection. It retrieves a connection from Spring's
 * transaction manager and returns it back to it when it is no longer needed.
 * <p>
 * If Spring's transaction handling is active it will no-op all commit/rollback/close calls assuming that the Spring
 * transaction manager will do the job.
 * <p>
 * If it is not it will behave like {@code JdbcTransaction}.
 *
 * @author Hunter Presnall
 * @author Eduardo Macarron
 */
public class SpringManagedTransaction implements Transaction {

  private static final Logger LOGGER = LoggerFactory.getLogger(SpringManagedTransaction.class);

  private final DataSource dataSource;

  private Connection connection;

  private boolean isConnectionTransactional;

  private boolean autoCommit;

  public SpringManagedTransaction(DataSource dataSource) {
    notNull(dataSource, "No DataSource specified");
    this.dataSource = dataSource;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public Connection getConnection() throws SQLException {
    if (this.connection == null) {
      openConnection();
    }
    return this.connection;
  }

  /**
   * Gets a connection from Spring transaction manager and discovers if this {@code Transaction} should manage
   * connection or let it to Spring.
   * <p>
   * It also reads autocommit setting because when using Spring Transaction MyBatis thinks that autocommit is always
   * false and will always call commit/rollback so we need to no-op that calls.
   */
  private void openConnection() throws SQLException {
    this.connection = DataSourceUtils.getConnection(this.dataSource);
    this.autoCommit = this.connection.getAutoCommit();
    this.isConnectionTransactional = DataSourceUtils.isConnectionTransactional(this.connection, this.dataSource);

    LOGGER.debug(() -> "JDBC Connection [" + this.connection + "] will"
        + (this.isConnectionTransactional ? " " : " not ") + "be managed by Spring");
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public void commit() throws SQLException {
    if (this.connection != null && !this.isConnectionTransactional && !this.autoCommit) {
      LOGGER.debug(() -> "Committing JDBC Connection [" + this.connection + "]");
      this.connection.commit();
    }
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public void rollback() throws SQLException {
    if (this.connection != null && !this.isConnectionTransactional && !this.autoCommit) {
      LOGGER.debug(() -> "Rolling back JDBC Connection [" + this.connection + "]");
      this.connection.rollback();
    }
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public void close() {
    DataSourceUtils.releaseConnection(this.connection, this.dataSource);
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public Integer getTimeout() {
    ConnectionHolder holder = (ConnectionHolder) TransactionSynchronizationManager.getResource(dataSource);
    if (holder != null && holder.hasTimeout()) {
      return holder.getTimeToLiveInSeconds();
    }
    return null;
  }

}

public class SpringManagedTransactionFactory implements TransactionFactory {

  /**
   * {@inheritDoc}
   */
  @Override
  public Transaction newTransaction(DataSource dataSource, TransactionIsolationLevel level, boolean autoCommit) {
    return new SpringManagedTransaction(dataSource);
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public Transaction newTransaction(Connection conn) {
    throw new UnsupportedOperationException("New Spring transactions require a DataSource");
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public void setProperties(Properties props) {
    // not needed in this version
  }

}

/**
 * The primary Java interface for working with MyBatis.
 * Through this interface you can execute commands, get mappers and manage transactions.
 *
 * @author Clinton Begin
 */

MappedStatement ms = configuration.getMappedStatement(statement);
// executor + mappedStatement
return executor.query(ms, wrapCollection(parameter), rowBounds, Executor.NO_RESULT_HANDLER);

分页插件
//args:你需要mybatis传入什么参数, type:你需要拦截的对象,method:要拦截的方法
@Intercepts(@Signature(type = StatementHandler.class,method ="prepare",args = {Connection.class,Integer.class}))
public class MyPagePlugin implements Interceptor {

    String databaseType = "";

    String pageSqlId = "";

    public String getDatabaseType() {
        return databaseType;
    }

    public void setDatabaseType(String databaseType) {
        this.databaseType = databaseType;
    }

    public String getPageSqlId() {
        return pageSqlId;
    }

    public void setPageSqlId(String pageSqlId) {
        this.pageSqlId = pageSqlId;
    }

    //我们自己拦截器里面的逻辑
    @Override
    public Object intercept(Invocation invocation) throws Throwable {

        StatementHandler statementHandler = (StatementHandler) invocation.getTarget();

//        statementHandler.getDelegate().getmappedStatement().getId();
//        Field delegate = StatementHandler.class.getDeclaredField("delegate");
//        delegate.setAccessible(true);
//        Object o = delegate.get(statementHandler);
//        o.getClass().getDeclaredField("mappedStatement").

        MetaObject metaObject = MetaObject.forObject(
                statementHandler, SystemMetaObject.DEFAULT_OBJECT_FACTORY,SystemMetaObject.DEFAULT_OBJECT_WRAPPER_FACTORY,new DefaultReflectorFactory());
        String sqlId = (String)metaObject.getValue("delegate.mappedStatement.id");
        //判断一下是否是分页
//        <!--第一步 执行一条couunt语句-->
        //1.1拿到连接
        //1.2 预编译SQL语句 拿到绑定的sql语句
        //1.3 执行 count语句   怎么返回你执行count的结果

//    <!--第二部 重写sql  select * from luban_product  limit start,limit -->
        //2.1 ？ 怎么知道 start 和limit
        //2.2拼接start 和limit
        //2.3 替换原来绑定sql
        //拿到原来应该执行的sql
        if (sqlId.matches(pageSqlId)){
            ParameterHandler parameterHandler = statementHandler.getParameterHandler();
            //原来应该执行的sql
            String sql = statementHandler.getBoundSql().getSql();
            //sql= select * from  product    select count(0) from (select * from  product) as a
            //select * from luban_product where name = #{name}
            //执行一条count语句
            //拿到数据库连接对象
            Connection connection = (Connection) invocation.getArgs()[0];
            String countSql = "select count(0) from ("+sql+") a";
            System.out.println(countSql);
            //渲染参数
            PreparedStatement preparedStatement = connection.prepareStatement(countSql);
            //条件交给mybatis
            parameterHandler.setParameters(preparedStatement);
            ResultSet resultSet = preparedStatement.executeQuery();
            int count =0;
            if (resultSet.next()) {
                count = resultSet.getInt(1);
            }
            resultSet.close();
            preparedStatement.close();
            //获得你传进来的参数对象
            Map<String, Object> parameterObject = (Map<String, Object>) parameterHandler.getParameterObject();
            //limit  page
            PageUtil pageUtil = (PageUtil) parameterObject.get("page");
            //limit 1 ,10  十条数据   总共可能有100   count 要的是 后面的100
            pageUtil.setCount(count);

            //拼接分页语句(limit) 并且修改mysql本该执行的语句
            String pageSql = getPageSql(sql, pageUtil);
            metaObject.setValue("delegate.boundSql.sql",pageSql);
            System.out.println(pageSql);
        }
        // 推进拦截器调用链
        return invocation.proceed();
    }

    public String getPageSql(String sql,PageUtil pageUtil){
        if(databaseType.equals("mysql")){
            return sql+" limit "+pageUtil.getStart()+","+pageUtil.getLimit();
        }else if(databaseType.equals("oracle")){
            //拼接oracle的分语句
        }

        return sql+" limit "+pageUtil.getStart()+","+pageUtil.getLimit();
    }


    //返回一个动态代理后的对象  target :StatementHandler
    @Override
    public Object plugin(Object target) {
        return Plugin.wrap(target,this);
    }

    //会传入配置文件内容 用户可根据配置文件自定义
    @Override
    public void setProperties(Properties properties) {

    }
}

// 把statementHandler.class的插件串成一条链
statementHandler = (StatementHandler) interceptorChain.pluginAll(statementHandler);

public class InterceptorChain {

  private final List<Interceptor> interceptors = new ArrayList<>();

  public Object pluginAll(Object target) {
    for (Interceptor interceptor : interceptors) {
      // 如果target.getClass有被拦截，返回代理对象
      target = interceptor.plugin(target);
    }
    return target;
  }

  public void addInterceptor(Interceptor interceptor) {
    interceptors.add(interceptor);
  }

  public List<Interceptor> getInterceptors() {
    return Collections.unmodifiableList(interceptors);
  }

}

public class Plugin implements InvocationHandler {

  private final Object target;
  private final Interceptor interceptor;
  private final Map<Class<?>, Set<Method>> signatureMap;

  private Plugin(Object target, Interceptor interceptor, Map<Class<?>, Set<Method>> signatureMap) {
    this.target = target;
    this.interceptor = interceptor;
    this.signatureMap = signatureMap;
  }

  public static Object wrap(Object target, Interceptor interceptor) {
    // 获得插件挂载的类接口
    Map<Class<?>, Set<Method>> signatureMap = getSignatureMap(interceptor);
    // 目标handler的类
    Class<?> type = target.getClass();
    // 查找目标handler类的所有接口是否存在和插件挂载的类接口一致，有则放入interfaces
    Class<?>[] interfaces = getAllInterfaces(type, signatureMap);
    if (interfaces.length > 0) {
      return Proxy.newProxyInstance(
          type.getClassLoader(),
          interfaces,
          new Plugin(target, interceptor, signatureMap));
    }
    return target;
  }

  @Override
  public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
    try {
      Set<Method> methods = signatureMap.get(method.getDeclaringClass());
      if (methods != null && methods.contains(method)) {
        return interceptor.intercept(new Invocation(target, method, args));
      }
      return method.invoke(target, args);
    } catch (Exception e) {
      throw ExceptionUtil.unwrapThrowable(e);
    }
  }

  private static Map<Class<?>, Set<Method>> getSignatureMap(Interceptor interceptor) {
    Intercepts interceptsAnnotation = interceptor.getClass().getAnnotation(Intercepts.class);
    // issue #251
    if (interceptsAnnotation == null) {
      throw new PluginException("No @Intercepts annotation was found in interceptor " + interceptor.getClass().getName());
    }
    Signature[] sigs = interceptsAnnotation.value();
    Map<Class<?>, Set<Method>> signatureMap = new HashMap<>();
    for (Signature sig : sigs) {
      Set<Method> methods = signatureMap.computeIfAbsent(sig.type(), k -> new HashSet<>());
      try {
        Method method = sig.type().getMethod(sig.method(), sig.args());
        methods.add(method);
      } catch (NoSuchMethodException e) {
        throw new PluginException("Could not find method on " + sig.type() + " named " + sig.method() + ". Cause: " + e, e);
      }
    }
    return signatureMap;
  }

  private static Class<?>[] getAllInterfaces(Class<?> type, Map<Class<?>, Set<Method>> signatureMap) {
    Set<Class<?>> interfaces = new HashSet<>();
    while (type != null) {
      for (Class<?> c : type.getInterfaces()) {
        if (signatureMap.containsKey(c)) {
          interfaces.add(c);
        }
      }
      type = type.getSuperclass();
    }
    return interfaces.toArray(new Class<?>[interfaces.size()]);
  }

}

public class Invocation {

  private final Object target;
  private final Method method;
  private final Object[] args;

  public Invocation(Object target, Method method, Object[] args) {
    this.target = target;
    this.method = method;
    this.args = args;
  }

  public Object getTarget() {
    return target;
  }

  public Method getMethod() {
    return method;
  }

  public Object[] getArgs() {
    return args;
  }

  public Object proceed() throws InvocationTargetException, IllegalAccessException {
    return method.invoke(target, args);
  }

}

@Intercepts(
    {
        @Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class}),
        @Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class, CacheKey.class, BoundSql.class}),
    }
)
public class PageInterceptor implements Interceptor 

public class MapperProxy<T> implements InvocationHandler, Serializable {
    @Override
  public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
    try {
      if (Object.class.equals(method.getDeclaringClass())) {
        return method.invoke(this, args);
      } else if (method.isDefault()) {
        // 下面两个invoke采用了java方法句柄的方式调用方法
        if (privateLookupInMethod == null) {
          return invokeDefaultMethodJava8(proxy, method, args);
        } else {
          return invokeDefaultMethodJava9(proxy, method, args);
        }
      }
    } catch (Throwable t) {
      throw ExceptionUtil.unwrapThrowable(t);
    }
    // 每个接口方法，对应一个方法执行
    final MapperMethod mapperMethod = cachedMapperMethod(method);
    return mapperMethod.execute(sqlSession, args);
  }
}

public class MapperMethod {

  private final SqlCommand command;
  private final MethodSignature method;

  public MapperMethod(Class<?> mapperInterface, Method method, Configuration config) {
    this.command = new SqlCommand(config, mapperInterface, method);
    this.method = new MethodSignature(config, mapperInterface, method);
  }

  public Object execute(SqlSession sqlSession, Object[] args) {
    Object result;
    switch (command.getType()) {
      case INSERT: {
        Object param = method.convertArgsToSqlCommandParam(args);
        result = rowCountResult(sqlSession.insert(command.getName(), param));
        break;
      }
      case UPDATE: {
        Object param = method.convertArgsToSqlCommandParam(args);
        result = rowCountResult(sqlSession.update(command.getName(), param));
        break;
      }
      case DELETE: {
        Object param = method.convertArgsToSqlCommandParam(args);
        result = rowCountResult(sqlSession.delete(command.getName(), param));
        break;
      }
      case SELECT:
        if (method.returnsVoid() && method.hasResultHandler()) {
          executeWithResultHandler(sqlSession, args);
          result = null;
        } else if (method.returnsMany()) {
          result = executeForMany(sqlSession, args);
        } else if (method.returnsMap()) {
          result = executeForMap(sqlSession, args);
        } else if (method.returnsCursor()) {
          result = executeForCursor(sqlSession, args);
        } else {
          Object param = method.convertArgsToSqlCommandParam(args);
          result = sqlSession.selectOne(command.getName(), param);
          if (method.returnsOptional()
              && (result == null || !method.getReturnType().equals(result.getClass()))) {
            result = Optional.ofNullable(result);
          }
        }
        break;
      case FLUSH:
        result = sqlSession.flushStatements();
        break;
      default:
        throw new BindingException("Unknown execution method for: " + command.getName());
    }
    if (result == null && method.getReturnType().isPrimitive() && !method.returnsVoid()) {
      throw new BindingException("Mapper method '" + command.getName()
          + " attempted to return null from a method with a primitive return type (" + method.getReturnType() + ").");
    }
    return result;
  }
  
}

/**
    * @param config : mybatis从xml中解析到全局配置
    * @param method ：执行的目标方法
    */
   public ParamNameResolver(Configuration config, Method method) {
       //通过反射获取参数列表的运行时类型
       final Class<?>[] paramTypes = method.getParameterTypes();
       //通过反射获取参数列表中每个参数对应的注解数组
       final Annotation[][] paramAnnotations = method.getParameterAnnotations();
       final SortedMap<Integer, String> map = new TreeMap<Integer, String>();
       int paramCount = paramAnnotations.length;
       //遍历参数列表，获取其参数名
       for (int paramIndex = 0; paramIndex < paramCount; paramIndex++) {
           if (isSpecialParameter(paramTypes[paramIndex])) {
               continue;
           }
           String name = null;
           for (Annotation annotation : paramAnnotations[paramIndex]) {
               //如果当前参数用@Param修饰，直接使用@Param的值作为参数名
               if (annotation instanceof Param) {
                   hasParamAnnotation = true;
                   name = ((Param) annotation).value();
                   break;
               }
           }
           //如果没有使用@Param或者@Param没有赋值，默认使用真实的参数名
           if (name == null) {
               if (config.isUseActualParamName()) {
                   name = getActualParamName(method, paramIndex);
               }
               //如果isUseActualParamName = false，则直接使用参数索引作为参数名
               if (name == null) {
                   name = String.valueOf(map.size());
               }
           }
           //key：参数的索引。value：上述解析到的参数Name
           map.put(paramIndex, name);
       }
       //通过Collections进行包装
       names = Collections.unmodifiableSortedMap(map);
}

public Object getNamedParams(Object[] args) {
       //names就是上面用Collections包装过的TreeMap
       final int paramCount = names.size();
       //根据TreeMap判断，如果没有参数列表，返回null，如果只有一个参数，直接返回数组中第一个元素。
       if (args == null || paramCount == 0) {
           return null;
       } else if (!hasParamAnnotation && paramCount == 1) {
           return args[names.firstKey()];
       } else {
           //当有两个及两个以上个参数时，构建一个ParamMap。关于ParamMap，大家可以先把它当做一个HashMap,
           //会在下面介绍。
           final Map<String, Object> param = new MapperMethod.ParamMap<Object>();
           int i = 0;
           //遍历TreeMap，相当于按序遍历方法的参数列表。
           for (Map.Entry<Integer, String> entry : names.entrySet()) {
               //args数组与TreeMap对于参数列表而言，是一一对应的，将参数名、参数值放入ParamMap中
               param.put(entry.getValue(), args[entry.getKey()]);
               //再将Param0、Param1...及对应value放入ParamMap中
               final String genericParamName = GENERIC_NAME_PREFIX + String.valueOf(i + 1);
               if (!names.containsValue(genericParamName)) {
                   param.put(genericParamName, args[entry.getKey()]);
               }
               i++;
           }
           //返回ParamMap
           return param;
       }
   }

@Bean
@ConditionalOnMissingBean
public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {
  SqlSessionFactoryBean factory = new SqlSessionFactoryBean();
  factory.setDataSource(dataSource);
  factory.setVfs(SpringBootVFS.class);
  if (StringUtils.hasText(this.properties.getConfigLocation())) {
    factory.setConfigLocation(this.resourceLoader.getResource(this.properties.getConfigLocation()));
  }
  applyConfiguration(factory);
  if (this.properties.getConfigurationProperties() != null) {
    factory.setConfigurationProperties(this.properties.getConfigurationProperties());
  }
  if (!ObjectUtils.isEmpty(this.interceptors)) {
    factory.setPlugins(this.interceptors);
  }
  if (this.databaseIdProvider != null) {
    factory.setDatabaseIdProvider(this.databaseIdProvider);
  }
  if (StringUtils.hasLength(this.properties.getTypeAliasesPackage())) {
    factory.setTypeAliasesPackage(this.properties.getTypeAliasesPackage());
  }
  if (this.properties.getTypeAliasesSuperType() != null) {
    factory.setTypeAliasesSuperType(this.properties.getTypeAliasesSuperType());
  }
  if (StringUtils.hasLength(this.properties.getTypeHandlersPackage())) {
    factory.setTypeHandlersPackage(this.properties.getTypeHandlersPackage());
  }
  if (!ObjectUtils.isEmpty(this.typeHandlers)) {
    factory.setTypeHandlers(this.typeHandlers);
  }
  if (!ObjectUtils.isEmpty(this.properties.resolveMapperLocations())) {
    factory.setMapperLocations(this.properties.resolveMapperLocations());
  }
  Set<String> factoryPropertyNames = Stream
      .of(new BeanWrapperImpl(SqlSessionFactoryBean.class).getPropertyDescriptors()).map(PropertyDescriptor::getName)
      .collect(Collectors.toSet());
  Class<? extends LanguageDriver> defaultLanguageDriver = this.properties.getDefaultScriptingLanguageDriver();
  if (factoryPropertyNames.contains("scriptingLanguageDrivers") && !ObjectUtils.isEmpty(this.languageDrivers)) {
    // Need to mybatis-spring 2.0.2+
    factory.setScriptingLanguageDrivers(this.languageDrivers);
    if (defaultLanguageDriver == null && this.languageDrivers.length == 1) {
      defaultLanguageDriver = this.languageDrivers[0].getClass();
    }
  }
  if (factoryPropertyNames.contains("defaultScriptingLanguageDriver")) {
    // Need to mybatis-spring 2.0.2+
    factory.setDefaultScriptingLanguageDriver(defaultLanguageDriver);
  }

  return factory.getObject();
}

targetConfiguration.setEnvironment(new Environment(this.environment,
		// 如果没有设置transactionFactory，则使用spring管理的事务工厂
    this.transactionFactory == null ? new SpringManagedTransactionFactory() : this.transactionFactory,
    this.dataSource));
    
    ....
      // 导入mapper sql语句
      if (this.mapperLocations != null) {
            if (this.mapperLocations.length == 0) {
                LOGGER.warn(() -> "Property 'mapperLocations' was specified but matching resources are not found.");
            } else {
                for (Resource mapperLocation : this.mapperLocations) {
                    if (mapperLocation == null) {
                        continue;
                    }
                    try {
                        XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(mapperLocation.getInputStream(),
                            targetConfiguration, mapperLocation.toString(), targetConfiguration.getSqlFragments());
                        xmlMapperBuilder.parse();
                    } catch (Exception e) {
                        throw new NestedIOException("Failed to parse mapping resource: '" + mapperLocation + "'", e);
                    } finally {
                        ErrorContext.instance().reset();
                    }
                    LOGGER.debug(() -> "Parsed mapper file: '" + mapperLocation + "'");
                }
            }
        } else {
            LOGGER.debug(() -> "Property 'mapperLocations' was not specified.");
        }

    
    return this.sqlSessionFactoryBuilder.build(targetConfiguration);

public SqlSessionFactory build(Configuration config) {
  return new DefaultSqlSessionFactory(config);
}

@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(HikariDataSource.class)
@ConditionalOnMissingBean(DataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "com.zaxxer.hikari.HikariDataSource",
      matchIfMissing = true)
static class Hikari {

   @Bean
   @ConfigurationProperties(prefix = "spring.datasource.hikari")
   HikariDataSource dataSource(DataSourceProperties properties) {
      HikariDataSource dataSource = createDataSource(properties, HikariDataSource.class);
      if (StringUtils.hasText(properties.getName())) {
         dataSource.setPoolName(properties.getName());
      }
      return dataSource;
   }

}

BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(MapperScannerConfigurer.class);

  private void processBeanDefinitions(Set<BeanDefinitionHolder> beanDefinitions) {
    GenericBeanDefinition definition;
    for (BeanDefinitionHolder holder : beanDefinitions) {
      definition = (GenericBeanDefinition) holder.getBeanDefinition();
      String beanClassName = definition.getBeanClassName();
      LOGGER.debug(() -> "Creating MapperFactoryBean with name '" + holder.getBeanName() + "' and '" + beanClassName
          + "' mapperInterface");

      // the mapper interface is the original class of the bean
      // but, the actual class of the bean is MapperFactoryBean
      definition.getConstructorArgumentValues().addGenericArgumentValue(beanClassName); // issue #59
      definition.setBeanClass(this.mapperFactoryBeanClass);

      definition.getPropertyValues().add("addToConfig", this.addToConfig);

      boolean explicitFactoryUsed = false;
      if (StringUtils.hasText(this.sqlSessionFactoryBeanName)) {
        definition.getPropertyValues().add("sqlSessionFactory",
            new RuntimeBeanReference(this.sqlSessionFactoryBeanName));
        explicitFactoryUsed = true;
      } else if (this.sqlSessionFactory != null) {
        definition.getPropertyValues().add("sqlSessionFactory", this.sqlSessionFactory);
        explicitFactoryUsed = true;
      }

      if (StringUtils.hasText(this.sqlSessionTemplateBeanName)) {
        if (explicitFactoryUsed) {
          LOGGER.warn(
              () -> "Cannot use both: sqlSessionTemplate and sqlSessionFactory together. sqlSessionFactory is ignored.");
        }
        definition.getPropertyValues().add("sqlSessionTemplate",
            new RuntimeBeanReference(this.sqlSessionTemplateBeanName));
        explicitFactoryUsed = true;
      } else if (this.sqlSessionTemplate != null) {
        if (explicitFactoryUsed) {
          LOGGER.warn(
              () -> "Cannot use both: sqlSessionTemplate and sqlSessionFactory together. sqlSessionFactory is ignored.");
        }
        definition.getPropertyValues().add("sqlSessionTemplate", this.sqlSessionTemplate);
        explicitFactoryUsed = true;
      }

      if (!explicitFactoryUsed) {
        LOGGER.debug(() -> "Enabling autowire by type for MapperFactoryBean with name '" + holder.getBeanName() + "'.");
        definition.setAutowireMode(AbstractBeanDefinition.AUTOWIRE_BY_TYPE);
      }
      definition.setLazyInit(lazyInitialization);
    }
  }

public class MapperFactoryBean<T> extends SqlSessionDaoSupport implements FactoryBean<T> {

  private Class<T> mapperInterface;

  private boolean addToConfig = true;

  public MapperFactoryBean() {
    // intentionally empty
  }

  public MapperFactoryBean(Class<T> mapperInterface) {
    this.mapperInterface = mapperInterface;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  protected void checkDaoConfig() {
    super.checkDaoConfig();

    notNull(this.mapperInterface, "Property 'mapperInterface' is required");

    Configuration configuration = getSqlSession().getConfiguration();
    if (this.addToConfig && !configuration.hasMapper(this.mapperInterface)) {
      try {
        configuration.addMapper(this.mapperInterface);
      } catch (Exception e) {
        logger.error("Error while adding the mapper '" + this.mapperInterface + "' to configuration.", e);
        throw new IllegalArgumentException(e);
      } finally {
        ErrorContext.instance().reset();
      }
    }
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public T getObject() throws Exception {
    return getSqlSession().getMapper(this.mapperInterface);
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public Class<T> getObjectType() {
    return this.mapperInterface;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public boolean isSingleton() {
    return true;
  }

  // ------------- mutators --------------

  /**
   * Sets the mapper interface of the MyBatis mapper
   *
   * @param mapperInterface
   *          class of the interface
   */
  public void setMapperInterface(Class<T> mapperInterface) {
    this.mapperInterface = mapperInterface;
  }

  /**
   * Return the mapper interface of the MyBatis mapper
   *
   * @return class of the interface
   */
  public Class<T> getMapperInterface() {
    return mapperInterface;
  }

  /**
   * If addToConfig is false the mapper will not be added to MyBatis. This means it must have been included in
   * mybatis-config.xml.
   * <p>
   * If it is true, the mapper will be added to MyBatis in the case it is not already registered.
   * <p>
   * By default addToConfig is true.
   *
   * @param addToConfig
   *          a flag that whether add mapper to MyBatis or not
   */
  public void setAddToConfig(boolean addToConfig) {
    this.addToConfig = addToConfig;
  }

  /**
   * Return the flag for addition into MyBatis config.
   *
   * @return true if the mapper will be added to MyBatis in the case it is not already registered.
   */
  public boolean isAddToConfig() {
    return addToConfig;
  }
}

public abstract class SqlSessionDaoSupport extends DaoSupport {

  private SqlSessionTemplate sqlSessionTemplate;

  /** 如果有设置SqlSessionTemplate和SqlSessionFactory，会优先用SqlSessionTemplate，如果没有设置SqlSessionTemplate，则会根据SqlSessionFactory自动创建sqlSessionTemplate
   * Set MyBatis SqlSessionFactory to be used by this DAO. Will automatically create SqlSessionTemplate for the given
   * SqlSessionFactory.
   *
   * @param sqlSessionFactory
   *          a factory of SqlSession
   */
  public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory) {
    if (this.sqlSessionTemplate == null || sqlSessionFactory != this.sqlSessionTemplate.getSqlSessionFactory()) {
      this.sqlSessionTemplate = createSqlSessionTemplate(sqlSessionFactory);
    }
  }

  /**
   * Create a SqlSessionTemplate for the given SqlSessionFactory. Only invoked if populating the DAO with a
   * SqlSessionFactory reference!
   * <p>
   * Can be overridden in subclasses to provide a SqlSessionTemplate instance with different configuration, or a custom
   * SqlSessionTemplate subclass.
   * 
   * @param sqlSessionFactory
   *          the MyBatis SqlSessionFactory to create a SqlSessionTemplate for
   * @return the new SqlSessionTemplate instance
   * @see #setSqlSessionFactory
   */
  @SuppressWarnings("WeakerAccess")
  protected SqlSessionTemplate createSqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {
    return new SqlSessionTemplate(sqlSessionFactory);
  }

  /**
   * Return the MyBatis SqlSessionFactory used by this DAO.
   *
   * @return a factory of SqlSession
   */
  public final SqlSessionFactory getSqlSessionFactory() {
    return (this.sqlSessionTemplate != null ? this.sqlSessionTemplate.getSqlSessionFactory() : null);
  }

  /**
   * Set the SqlSessionTemplate for this DAO explicitly, as an alternative to specifying a SqlSessionFactory.
   *
   * @param sqlSessionTemplate
   *          a template of SqlSession
   * @see #setSqlSessionFactory
   */
  public void setSqlSessionTemplate(SqlSessionTemplate sqlSessionTemplate) {
    this.sqlSessionTemplate = sqlSessionTemplate;
  }

  /**
   * Users should use this method to get a SqlSession to call its statement methods This is SqlSession is managed by
   * spring. Users should not commit/rollback/close it because it will be automatically done.
   *
   * @return Spring managed thread safe SqlSession
   */
  public SqlSession getSqlSession() {
    return this.sqlSessionTemplate;
  }

  /**
   * Return the SqlSessionTemplate for this DAO, pre-initialized with the SessionFactory or set explicitly.
   * <p>
   * <b>Note: The returned SqlSessionTemplate is a shared instance.</b> You may introspect its configuration, but not
   * modify the configuration (other than from within an {@link #initDao} implementation). Consider creating a custom
   * SqlSessionTemplate instance via {@code new SqlSessionTemplate(getSqlSessionFactory())}, in which case you're
   * allowed to customize the settings on the resulting instance.
   *
   * @return a template of SqlSession
   */
  public SqlSessionTemplate getSqlSessionTemplate() {
    return this.sqlSessionTemplate;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  protected void checkDaoConfig() {
    notNull(this.sqlSessionTemplate, "Property 'sqlSessionFactory' or 'sqlSessionTemplate' are required");
  }

}

public SqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType,
    PersistenceExceptionTranslator exceptionTranslator) {

  notNull(sqlSessionFactory, "Property 'sqlSessionFactory' is required");
  notNull(executorType, "Property 'executorType' is required");

  this.sqlSessionFactory = sqlSessionFactory;
  this.executorType = executorType;
  this.exceptionTranslator = exceptionTranslator;
  this.sqlSessionProxy = (SqlSession) newProxyInstance(
      SqlSessionFactory.class.getClassLoader(),
      new Class[] { SqlSession.class },
      new SqlSessionInterceptor());
}

private class SqlSessionInterceptor implements InvocationHandler {
  @Override
  public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
    SqlSession sqlSession = getSqlSession(
        SqlSessionTemplate.this.sqlSessionFactory,
        SqlSessionTemplate.this.executorType,
        SqlSessionTemplate.this.exceptionTranslator);
    try {
      Object result = method.invoke(sqlSession, args);
      if (!isSqlSessionTransactional(sqlSession, SqlSessionTemplate.this.sqlSessionFactory)) {
        // force commit even on non-dirty sessions because some databases require
        // a commit/rollback before calling close()
        sqlSession.commit(true);
      }
      return result;
    } catch (Throwable t) {
      Throwable unwrapped = unwrapThrowable(t);
      if (SqlSessionTemplate.this.exceptionTranslator != null && unwrapped instanceof PersistenceException) {
        // release the connection to avoid a deadlock if the translator is no loaded. See issue #22
        closeSqlSession(sqlSession, SqlSessionTemplate.this.sqlSessionFactory);
        sqlSession = null;
        Throwable translated = SqlSessionTemplate.this.exceptionTranslator.translateExceptionIfPossible((PersistenceException) unwrapped);
        if (translated != null) {
          unwrapped = translated;
        }
      }
      throw unwrapped;
    } finally {
      if (sqlSession != null) {
        closeSqlSession(sqlSession, SqlSessionTemplate.this.sqlSessionFactory);
      }
    }
  }
}