大纲:

• ResultSetHandler 结果集处理器的作用
• ResultSetHandler 接口以及方法介绍
• ResultSetHandler 默认实现类DefaultResultSetHandler

ResultSetHandler 结果集处理器的作用

ResultSetHandler 结果集处理器,用于 StatementHandler对象执行完操作后,对结果集进行处理

ResultSetHandler 接口以及方法介绍

public interface ResultSetHandler {
  /**
   * 获取 jdbc Statement对象中的 ResultSet对象,对ResultSet对象进行处理,返回包含结果实体的 List 对象列表
   * @return
   * @throws SQLException
   */
   List handleResultSets(Statement stmt) throws SQLException;
  
  /**
   * 将ResultSet对象 包装成 Cursor对象,对Cursor进行遍历时,能够动态的从数据库查询数据,避免一次性将所有数据加载到内存中
   * @return
   * @throws SQLException
   */
   Cursor handleCursorResultSets(Statement stmt) throws SQLException;
 
  /**
   * 处理存储过程调用结果
   * @param cs
   * @throws SQLException
   */
  void handleOutputParameters(CallableStatement cs) throws SQLException;
}

ResultSetHandler 默认实现类DefaultResultSetHandler

ResultSetHandler 只有一个默认实现类DefaultResultSetHandler

public class DefaultResultSetHandler implements ResultSetHandler {
  private static final Object DEFERRED = new Object();
  private final Executor executor;
  private final Configuration configuration;
  private final MappedStatement mappedStatement;
  private final RowBounds rowBounds;
  private final ParameterHandler parameterHandler;
  private final ResultHandler<?> resultHandler;
  private final BoundSql boundSql;
  private final TypeHandlerRegistry typeHandlerRegistry;
  private final ObjectFactory objectFactory;
  private final ReflectorFactory reflectorFactory;


  //
  // HANDLE RESULT SETS
  //
  @Override
  public List