Java 要列出的结果集
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Resultset To List
提问by Gnaniyar Zubair
I want to convert my Resultset to List in my JSP page. and want to display all the values. This is my query:
我想在我的 JSP 页面中将我的结果集转换为列表。并希望显示所有值。这是我的查询：
SELECT userId, userName
FROM user;
I have executed that using preparedstatementand got the Resultset. But how to convert it as a Listand want to display the result like this:
我已经执行，使用PreparedStatement的，并得到了结果集。但是如何将其转换为List并希望像这样显示结果：
userID userName
------------------
1001 user-X
1006 user-Y
1007 user-Z
采纳答案by OMG Ponies
You need to iterate over the ResultSetobject in a loop, row by row, to pull out each column value:
您需要在循环中逐行迭代ResultSet对象，以提取每个列值：
List ll = new LinkedList();
ResultSet rs = stmt.executeQuery("SELECT userid, username FROM USER");
// Fetch each row from the result set
while (rs.next()) {
int i = rs.getInt("userid");
String str = rs.getString("username");
//Assuming you have a user object
User user = new User(i, str);
ll.add(user);
}
回答by Brian Agnew
You could always use Commons DbUtilsand the MapListHandler. From the doc:
您始终可以使用Commons DbUtils和MapListHandler。从文档：
ResultSetHandler implementation that converts a ResultSet into a List of Maps
将 ResultSet 转换为 Maps 列表的 ResultSetHandler 实现
so it'll take a lot of boilerplate code out of your hands.
所以它会从你手中拿走很多样板代码。
回答by duffymo
A ResultSet should never get as far as a JSP. It should be mapping into a data structure or object and closed inside the method scope in which it was created. It's a database cursor, a scarce resource. Your app will run out of them soon if you persist with such a design.
ResultSet 永远不会像 JSP 那样深入。它应该映射到数据结构或对象中，并在创建它的方法范围内关闭。它是一个数据库游标，一种稀缺资源。如果您坚持这样的设计，您的应用程序很快就会耗尽它们。
