Spring JDBC样例

这里介绍一下通过Spring JDBC的方式进行数据库的增删改查的操作。
在进行程序的编写之前我们需要在本地MySQL数据库中创建一张User表，如下所示：

create database user_db;
use user_db;
create table userinfo (
    id int,
    username varchar(30),
    password varchar(30)
);

创建完这个表以后，我们需要创建一个User类与之对应：

package com.myspring.obj;

public class User {
    private int id;
    private String username;
    private String password;
    public User() {}
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    @Override
    public String toString() {
        return "[" + id + "," + username + "," + password + "]";
    }
}

然后我们需要创建一个Dao类UseDao用于操作数据：

package com.myspring.dao;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.core.support.JdbcDaoSupport;

import com.myspring.obj.User;

public class UserDao extends JdbcDaoSupport {
    class UserRowMapper implements RowMapper<User> {
        public User mapRow(ResultSet rs, int rowNum) throws SQLException {
            User user = new User();
            user.setId(rs.getInt("id"));
            user.setUsername(rs.getString("username"));
            user.setPassword(rs.getString("password"));
            return user;
        }
    }
    public List<User> queryAll() {
        return getJdbcTemplate().query("select * from userinfo", new UserRowMapper());
    }
    public List<User> queryByUsername(String username) {
        return getJdbcTemplate().query("select * from userinfo where username=?",
                                        new Object[] { username }, new UserRowMapper());
    }
    public void create(User user) {
        getJdbcTemplate().update("insert into userinfo (id,username,password) values (?,?,?)", 
                                        new Object[] { user.getId(), user.getUsername(), user.getPassword() });
    }
    public void update(User user) {
        getJdbcTemplate().update("update userinfo set username=?,password=? where id=?",
                                        new Object[] { user.getUsername(), user.getPassword(), user.getId() });
    }
    public void delete(int id) {
        getJdbcTemplate().update("delete from userinfo where id=?", new Object[] { id });
    }
}

在src/main/resources/目录下创建一个spring-jdbc.xml文件用于配置数据库的相关信息，这些信息将会保存到一个dataSource Bean中，这个dataSource又作为内部的属性保存在了jdbcTemplateUserDao Bean中，这个Bean是一个UserDao对应一个UserDao类型。

<?xml version="1.0" encoding="UTF-8"?>  
<beans xmlns="http://www.springframework.org/schema/beans"  
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
    xsi:schemaLocation="http://www.springframework.org/schema/beans  
           http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">  
  
  
    <bean id="dataSource"  
        class="org.springframework.jdbc.datasource.DriverManagerDataSource">  
        <property name="driverClassName" value="com.mysql.jdbc.Driver" />  
        <property name="url" value="jdbc:mysql://localhost:3306/user_db" />  
        <property name="username" value="root" />  
        <property name="password" value="password" />  
    </bean>  
  
  
    <bean id="jdbcTemplateUserDao" class="com.myspring.dao.UserDao">
        <property name="dataSource" ref="dataSource" />  
    </bean>  
  
</beans>  

最后创建一个测试类SpringJdbcPractice类用于测试：

package com.myspring.study;

import java.util.List;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.myspring.dao.UserDao;
import com.myspring.obj.User;

public class SpringJdbcPractice {
    @SuppressWarnings("resource")
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("spring-jdbc.xml");
        UserDao userDao = (UserDao) context.getBean("jdbcTemplateUserDao");
        User user = new User();
        for (int i = 1; i <= 3; i ++) {
            user.setId(i);
            user.setUsername("user" + i);
            user.setPassword("passwd" + i);
            userDao.create(user);
        }
        System.out.println("begin to query all ...");
        List<User> users = userDao.queryAll();
        for (User u : users)
            System.out.println(u);
        System.out.println("begin to query user with name 'user2' ...");
        users = userDao.queryByUsername("user2");
        for (User u : users)
            System.out.println(u);
        System.out.println("begin to update 'user2' ...");
        user.setId(2);
        user.setUsername("user2");
        user.setPassword("moonlit");
        userDao.update(user);
        System.out.println("get user2 after update ...");
        users = userDao.queryByUsername("user2");
        for (User u : users)
            System.out.println(u);
        System.out.println("delete 'user3' ...");
        userDao.delete(3);
        System.out.println("query all after delete ...");
        users = userDao.queryAll();
        for (User u : users)
            System.out.println(u);
    }
}

输出效果如下：

begin to query all ...
[1,user1,passwd1]
[2,user2,passwd2]
[3,user3,passwd3]
begin to query user with name 'user2' ...
[2,user2,passwd2]
begin to update 'user2' ...
get user2 after update ...
[2,user2,moonlit]
delete 'user3' ...
query all after delete ...
[1,user1,passwd1]
[2,user2,moonlit]