mybatis源码之SimpleStatementHandler

/**
 * @author Clinton Begin
 */
public class SimpleStatementHandler extends BaseStatementHandler {

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

  @Override
  public int update(Statement statement) throws SQLException {
  //获得sql语句？  
    String sql = boundSql.getSql();
  //获得参数？
    Object parameterObject = boundSql.getParameterObject();
    KeyGenerator keyGenerator = mappedStatement.getKeyGenerator();
    int rows;
  //statement执行sql语句返回更新数目
    if (keyGenerator instanceof Jdbc3KeyGenerator) {
      statement.execute(sql, Statement.RETURN_GENERATED_KEYS);
      rows = statement.getUpdateCount();
      keyGenerator.processAfter(executor, mappedStatement, statement, parameterObject);
    } else if (keyGenerator instanceof SelectKeyGenerator) {
      statement.execute(sql);
      rows = statement.getUpdateCount();
      keyGenerator.processAfter(executor, mappedStatement, statement, parameterObject);
    } else {
      statement.execute(sql);
      rows = statement.getUpdateCount();
    }
    return rows;
  }

  @Override
  public void batch(Statement statement) throws SQLException {
  //批处理
    String sql = boundSql.getSql();
    statement.addBatch(sql);
  }

  //ResultHandler resultHandler这个参数好像没用啊
  @Override
  public <E> List<E> query(Statement statement, ResultHandler resultHandler) throws SQLException {
    String sql = boundSql.getSql();
  //statement执行sql语句
    statement.execute(sql);
    return resultSetHandler.<E>handleResultSets(statement);
  }

  @Override
  protected Statement instantiateStatement(Connection connection) throws SQLException {
    if (mappedStatement.getResultSetType() != null) {
      return connection.createStatement(mappedStatement.getResultSetType().getValue(), ResultSet.CONCUR_READ_ONLY);
    } else {
      return connection.createStatement();
    }
  }

  @Override
  public void parameterize(Statement statement) throws SQLException {
    // N/A
  }

}