在Java中处理ResultSet的有效方法 [英] Efficient way to Handle ResultSet in Java

问题描述

我在Java中使用ResultSet，并不确定如何正确关闭它。我正在考虑使用ResultSet构造一个HashMap，然后关闭ResultSet。这种HashMap技术是否有效，还是有更有效的方法来处理这种情况？我需要键和值，所以使用HashMap看起来像是一个合理的选择。

I'm using a ResultSet in Java, and am not sure how to properly close it. I'm considering using the ResultSet to construct a HashMap and then closing the ResultSet after that. Is this HashMap technique efficient, or are there more efficient ways of handling this situation? I need both keys and values, so using a HashMap seemed like a logical choice.

如果使用HashMap是最有效的方法，那么如何构造和使用HashMap在我的代码中？

If using a HashMap is the most efficient method, how do I construct and use the HashMap in my code?

以下是我试过的：

Here's what I've tried:

public HashMap resultSetToHashMap(ResultSet rs) throws SQLException {

  ResultSetMetaData md = rs.getMetaData();
  int columns = md.getColumnCount();
  HashMap row = new HashMap();
  while (rs.next()) {
     for (int i = 1; i <= columns; i++) {
       row.put(md.getColumnName(i), rs.getObject(i));
     }
  }
  return row;
}

推荐答案

1. 遍历ResultSet


2. 为每行创建一个新对象，以存储您需要的字段
   
3. 将此新对象添加到ArrayList或Hashmap或无论你喜欢什么


4. 关闭ResultSet，Statement和数据库连接
   

1. Iterate over the ResultSet
2. Create a new Object for each row, to store the fields you need
3. Add this new object to ArrayList or Hashmap or whatever you fancy
4. Close the ResultSet, Statement and the DB connection

完成

编辑：现在您已经发布了代码，我已对其进行了一些更改。

now that you have posted code, I have made a few changes to it.

public List resultSetToArrayList(ResultSet rs) throws SQLException{
  ResultSetMetaData md = rs.getMetaData();
  int columns = md.getColumnCount();
  ArrayList list = new ArrayList(50);
  while (rs.next()){
     HashMap row = new HashMap(columns);
     for(int i=1; i<=columns; ++i){           
      row.put(md.getColumnName(i),rs.getObject(i));
     }
      list.add(row);
  }

 return list;
}

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