Apache dbutils 用法
学习java免不了和数据库打交道。下面我介绍下apache的一个类库，很好用的，没那么多的get和set了，因为我们知道使用javabean来对数据库中的字段进行封装保存，取出免不了get，设置又要set。而今天这个类库就不用，
他就是 commons-dbutils-1.1.jar，也不知道大家有没有用过的，心得大家一块分享下。
首先我们先看一个我们常规的得到查询数据库所得到的ResultSet。
1、表：person：字段：username,id,age .要查id为1 的用户信息, 用javabean封装，PersonVo
1. publicPersonVo getInfo(int id) throws Exception {
2. PersonVo pv = new PersonVo();
3. String sql = "SELECT * FROM person WHERE id = " + id;
4. Connection connection = super.getConnection();
5. Statement statement = connection.createStatement();
6. ResultSet rs = statement.executeQuery(sql);
7. while (rs.next()) {
8. pv.setId(rs.getInt(1));
9. pv.setUsername(rs.getString(2));
10. pv.setAge(rs.getInt(3));
11. }
publicPersonVo getInfo(int id) throws Exception {
PersonVo pv = new PersonVo();
String sql = "SELECT * FROM person WHERE id = " + id;
Connection connection = super.getConnection();
Statement statement = connection.createStatement();
ResultSet rs = statement.executeQuery(sql);
while (rs.next()) {
pv.setId(rs.getInt(1));
pv.setUsername(rs.getString(2));
pv.setAge(rs.getInt(3));
}
ok，我们得到了。
下面开始介绍dbutils.jar
今天我们主要使用org.apache.commons.dbutils.handler下面的类
主要的类有： ArrayHandler,ArrayListHandler,BeanHandler,BeanListHandler,MapHandler,MapListHandler
1.同样是要得到一条结果，那我们就可以用ArrayHandler或BeanHandler或MapHandler.
下面看方法
1. public PersonVo getInfo(int id) throws Exception {
2. QueryRunner queryRunner = new QueryRunner();
3. String sql = "select * from person where id = " + id;
4. return(PersonVo)queryRunner.query(getConnection(), sql,new BeanHandler(PersonVo.class));
5. }
public PersonVo getInfo(int id) throws Exception {
QueryRunner queryRunner = new QueryRunner();
String sql = "select * from person where id = " + id;
return(PersonVo)queryRunner.query(getConnection(), sql,new BeanHandler(PersonVo.class));
QueryRunner我个人觉得和我们以前用过的Statement差不多。
他有一个方法query(java.sql.Connection conn, java.lang.String sql, ResultSetHandler rsh) ，其他的大家可以下载下来
自己试着用下。
getConnection() 是拿到一个和数据库的Connection。
这样我们在前台，就直接可以
1. PersonVo pv = new Test().getInfo(1);
2. System.out.println(pv.getUsername());
PersonVo pv = new Test().getInfo(1);
System.out.println(pv.getUsername());
如果结果有一条以上，就要用BeanListHandler,MapListHandler.
如：
1. public List<PersonVo> getRegist3() throws Exception {
2. QueryRunner queryRunner = new QueryRunner();
3. String sql = "select * from person";
4. return(List)queryRunner.query(getConnection(), sql,new BeanListHandler(PersonVo.class));
5. }
public List<PersonVo> getRegist3() throws Exception {
QueryRunner queryRunner = new QueryRunner();
String sql = "select * from person";
return(List)queryRunner.query(getConnection(), sql,new BeanListHandler(PersonVo.class));
}
---------------
ps：MapHandler
3.
1. public Map getRegist() throws Exception {
2. QueryRunner queryRunner = new QueryRunner();
3. String sql = "select * from person where id = 2";
4. return (Map) queryRunner.query(getConnection(), sql,new MapHandler());
5. }
public Map getRegist() throws Exception {
QueryRunner queryRunner = new QueryRunner();
String sql = "select * from person where id = 2";
return (Map) queryRunner.query(getConnection(), sql,new MapHandler());
}
MapListHandler
4.
1. public List<Map> getRegist4() throws Exception {
2. QueryRunner queryRunner = new QueryRunner();
3. String sql = "select * from person";
4. return(List)queryRunner.query(getConnection(), sql,new MapListHandler());
5. }
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