MyBatis(三) 简单的 CRUD

2024-04-27 15:17:06

字体：大中小

来源：转载

供稿：网友

写好了前面的入门程序，现在我们来开始写简单的增删改查：添加用户前面已经写了，下面为了测试我们就多插入几条数据。这里写图片描述

进入正题 1、’删’ ‘改’ ‘查’ 用户，首先在原来的 User.xml 表中添加下面的代码：注意事项： - 这里需要说明的是：parameterType 代表传入参数类型，：resultType代表返回数据类型 - 如果修改需要传入多个参数时，可以传入一个对象作为参数。

<?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"><mapper namespace="user">  <insert id="insert" parameterType="com.zll.TestMyBatis.bean.User"> insert into user(parentId,sonId,name,birthday) value(#{parentId},#{sonId},#{name},#{birthday}) </insert>  <insert id="insertReteunId" parameterType="com.zll.TestMyBatis.bean.User"> <selectKey keyPRoperty="id" order="AFTER" resultType="int">  select last_insert_id(); </selectKey> insert into user(parentId,sonId,name,birthday) value(#{parentId},#{sonId},#{name},#{birthday}) </insert>  <insert id="insertReteunUId" parameterType="com.zll.TestMyBatis.bean.User"> <selectKey keyProperty="id" order="BEFORE" resultType="string"> select uuid; </selectKey> insert into user(parentId,sonId,name,birthday) value(#{parentId},#{sonId},#{name},#{birthday}) </insert>  <delete id="deleteById" parameterType="int"> delete from user where id=#{id} </delete>  <update id="updateById" parameterType="com.zll.TestMyBatis.bean.User"> update user set parentId=#{parentId},sonId=#{sonId},name=#{name},birthday=#{birthday} where id=#{id} </update>   <select id="findByName" parameterType="string" resultType="com.zll.TestMyBatis.bean.User">  select * from user where name like #{value} </select></mapper>

进入测试代码：插入用户并返回id：

public void insertUserRetrunId() throws IOException { String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); SqlsessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); SqlSession session = sqlSessionFactory.openSession(); User user = new User(); user.setName("小红"); user.setBirthday(new Date()); session.insert("user.insertReteunId", user); session.commit(); //注意前面没有设置id，这里返回的是我们刚插入数据的id System.out.println("这是刚插入的数据id = "+user.getId()); session.close(); }

测试结果查看控制台

模糊查询：

public void findUser() throws IOException { String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); SqlSession session = sqlSessionFactory.openSession(); //模糊查询 "%#{}%" //List<User> list = session.selectList("user.findByName", "小"); //模糊查询推荐方式 List<User> list = session.selectList("user.findByName", "%小%"); for(int i=0; i<list.size(); i++){ System.out.println(list.get(i)); } session.close(); }

执行结果这里写图片描述

修改操作

//修改了小明为小明明并设置parentid为3 public void updateUser() throws IOException { String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); SqlSession session = sqlSessionFactory.openSession(); User user = new User(); user.setId(4); user.setParentId(3); user.setName("小明明"); user.setBirthday(new Date()); session.update("user.updateById", user); session.commit(); session.close(); }

执行结果：

删除操作

//删除了小红 public void deleteUser() throws IOException { String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); SqlSession session = sqlSessionFactory.openSession(); session.delete("user.deleteById", 7); session.commit(); session.close(); }

执行结果：这里写图片描述