MyBatis学习笔记（三）数据的增删改查 CRUD操作

来源：互联网发布：nasa直播软件编辑：程序博客网时间：2024/04/30 10:24

MyBatis学习笔记（三）数据的增删改查 CRUD操作
我们接着上篇的环境，继续讲如何对表执行CRUD操作

1.基于XML实现CRUD

定义sql映射xml文件，UsersMapper.xml如下：

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><!-- 为这个mapper指定一个唯一的namespace，namespace的值习惯上设置成包名+sql映射文件名，这样就能够保证namespace的值是唯一的 --><mapper namespace="com.mapping.UsersMapper">    <!-- 根据id查询得到一个user对象     -->    <select id="getUser" parameterType="int" resultType="Users">        select * from users where id=#{id}    </select>    <!-- 创建用户 -->    <insert id="addUser" parameterType="Users">        insert into users(name, age, address) values(#{name}, #{age}, #{address})    </insert>    <!-- 删除用户 -->    <delete id="deleteUser" parameterType="int">        delete from users where id=#{id}    </delete>    <!-- 修改用户 -->    <select id="updateUser" parameterType="Users">        update users set name=#{name}, age=#{age}, address=#{address} where id=#{id};    </select>    <!-- 查询全部用户 -->    <select id="getAllUsers" resultType="Users">        select * from users    </select></mapper>

测试用例:

package com.test;import java.util.List;import org.apache.ibatis.session.SqlSession;import com.model.Users;import com.util.MyBatisUtil;/** * * @author wenjuanhenxing * @version Test.java 2015年12月4日 上午10:34:26 */public class Test {    public static void testGetUser() {        // 使用工具类创建session        SqlSession sqlSession = MyBatisUtil.getSqlSession();        /**         * 映射sql的标识字符串，         * com.mapping.UsersMapper是UsersMapper.xml文件中mapper标签的namespace属性的值，         * getUser是select标签的id属性值，通过select标签的id属性值就可以找到要执行的SQL         */        String stmt = "com.mapping.UsersMapper.getUser";        Users user = sqlSession.selectOne(stmt, 1);        // 执行完关闭session        MyBatisUtil.closeSession(sqlSession);        System.out.println(user);    }    public static void testAddUser() {        SqlSession sqlSession = MyBatisUtil.getSqlSession(true);        String stmt = "com.mapping.UsersMapper.addUser";        Users user = new Users();        user.setName("你好");        user.setAge(18);        user.setAddress("中国");        int retResult = sqlSession.insert(stmt, user);        // 手动提交事务        // sqlSession.commit();        // 使用SqlSession执行完SQL之后需要关闭SqlSession        MyBatisUtil.closeSession(sqlSession);        System.out.println(retResult);    }    public static void testDeleteUser() {        SqlSession sqlSession = MyBatisUtil.getSqlSession(true);        String stmt = "com.mapping.UsersMapper.deleteUser";        int result = sqlSession.delete(stmt, 2);        MyBatisUtil.closeSession(sqlSession);        System.out.println(result);    }    public static void testUpdateUser() {        SqlSession sqlSession = MyBatisUtil.getSqlSession(true);        String stmt = "com.mapping.UsersMapper.updateUser";        Users user = new Users();        user.setId(3);        user.setName("赵六");        user.setAge(50);        int result = sqlSession.update(stmt, user);        MyBatisUtil.closeSession(sqlSession);        System.out.println(result);    }    public static void testGetAllUsers() {        SqlSession sqlSession = MyBatisUtil.getSqlSession();        String stmt = "com.mapping.UsersMapper.getAllUsers";        // 执行查询操作，将查询结果自动封装成List<User>返回        List<Users> list = sqlSession.selectList(stmt);        MyBatisUtil.closeSession(sqlSession);        System.out.println(list);    }    public static void main(String[] args) {        testGetAllUsers();        testGetUser();        testAddUser();        testDeleteUser();        testUpdateUser();        testGetAllUsers();    }}

0 0