Mybatis执行SimpleExecutor（三）

SimpleExecutor通过类名可以看出，它是一个简单的执行类，并不会做一些处理就执行sql，源码及分析如下：

/**
 * @author Clinton Begin
 */
public class SimpleExecutor extends BaseExecutor {

  public SimpleExecutor(Configuration configuration, Transaction transaction) {
    super(configuration, transaction);
  }

  @Override
  public int doUpdate(MappedStatement ms, Object parameter) throws SQLException {
    Statement stmt = null;
    try {
	  //获得配置文件对象
      Configuration configuration = ms.getConfiguration();
	  //获得statementHandler里面有statement，来处理
      StatementHandler handler = configuration.newStatementHandler(this, ms, parameter, RowBounds.DEFAULT, null, null);
      stmt = prepareStatement(handler, ms.getStatementLog());
	  //最终是一个statement进行处理
      return handler.update(stmt);
    } finally {
      closeStatement(stmt);
    }
  }

  @Override
  public <E> List<E> doQuery(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {
    Statement stmt = null;
    try {
	  //获得配置文件对象
      Configuration configuration = ms.getConfiguration();
	  //获得statementHandler里面有statement，来处理
      StatementHandler handler = configuration.newStatementHandler(wrapper, ms, parameter, rowBounds, resultHandler, boundSql);
	  //获得statement
      stmt = prepareStatement(handler, ms.getStatementLog());
	  //最终是一个statement进行处理
      return handler.<E>query(stmt, resultHandler);
    } finally {
      closeStatement(stmt);
    }
  }

  @Override
  public List<BatchResult> doFlushStatements(boolean isRollback) throws SQLException {
    return Collections.emptyList();
  }

  private Statement prepareStatement(StatementHandler handler, Log statementLog) throws SQLException {
    Statement stmt;
    Connection connection = getConnection(statementLog);
    stmt = handler.prepare(connection);
	//将Statement转为PrepareStatement
    handler.parameterize(stmt);
    return stmt;
  }

}