類似startTransaction，都是轉發給SqlMapExecutorDelegate的endTransaction。

  /**
   * End the transaction on a session
   *
   * @param sessionScope - the session
   * @throws SQLException - if the transaction could not be ended
   */
  public void endTransaction(SessionScope sessionScope) throws SQLException {
    try {
      try {
        sqlExecutor.cleanup(sessionScope);
      } finally {
        txManager.end(sessionScope);
      }
    } catch (TransactionException e) {
      throw new NestedSQLException("Error while ending transaction.  Cause: " + e, e);
    }
  }
 

  public void end(SessionScope sessionScope) throws SQLException, TransactionException {
    Transaction trans = sessionScope.getTransaction();
    TransactionState state = sessionScope.getTransactionState();

    if (state == TransactionState.STATE_USER_PROVIDED) {
      throw new TransactionException("TransactionManager could not end this transaction.  " +
          "A user provided connection is currently being used by this session.  " +
          "You must call the rollback() method of the Connection directly.  " +
          "The calling .setUserConnection (null) will clear the user provided transaction.");
    }

    try {
      if (trans != null) {
        try {
          if (state != TransactionState.STATE_COMMITTED) {
            if (sessionScope.isCommitRequired() || config.isForceCommit()) {
              trans.rollback();
              sessionScope.setCommitRequired(false);
            }
          }
        } finally {
          sessionScope.closePreparedStatements();
          trans.close();
        }
      }
    } finally {
      sessionScope.setTransaction(null);
      sessionScope.setTransactionState(TransactionState.STATE_ENDED);
    }
  }
 

      事務的提交操作會根據當前SessionScope的事務資訊判斷是否需要回滾，只有當前事務狀態為非提交狀態，同時，提交標識為真時，才會呼叫Transaction的rollback操作。在兩種情況下會出現SQL的回滾：

      第一種，在MappedStatement的executeUpdate操作中，會設定事務的提交標識為真，並且只有在正確執行完成SQL後才會設定事務狀態為已提交狀態。如果整個流程中出現異常，那麼這條SQL就會回滾。

      第二種，使用者執行了startTransaction，但是沒有呼叫commitTransaction方法，那麼這期間的SQL都會回滾。