增删改查CRUD

mybatis-config.xml核心配置文件：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">



<!--useSSL=true&amp;characterEncoding=UTF-8&amp;useUnicode=true&amp;serverTimezone=GMT-->
<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatistest?useSSL=false&amp;useUnicode=true&amp;CharacterEncoding=UTF8&amp;serverTimezone=GMT"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>


    <mappers>
        <mapper resource="com/kakafa/dao/UserMapper.xml"></mapper>
    </mappers>

</configuration>

MyBatisutils:

package com.kakafa.util;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;

public class MybatisUtils {


    private static SqlSessionFactory sqlSessionFactory;
    static{

        try {

            //使用mybatis第一步:获取sqlSessionFactory对象
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //既然有了 SqlSessionFactory，顾名思义，我们可以从中获得 SqlSession 的实例。
    //SqlSession 提供了在数据库执行 SQL 命令所需的所有方法。你可以通过 SqlSession 实例来直接执行已映射的 SQL 语句。
    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();
    }

}

User

package com.kakafa.pojo;

public class User {

    private int id;
    private String name;
    private String pwd;


    public User() {
    }

    public User(int id, String name, String pwd) {
        this.id = id;
        this.name = name;
        this.pwd = pwd;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", pwd='" + pwd + '\'' +
                '}';
    }
}

UserMapper

package com.kakafa.dao;

import com.kakafa.pojo.User;

import java.util.List;

public interface UserMapper{

    //获取全部用户
    List<User> getUserList();

    //根据id查询用户
    User getUserById(int id);

    //插入一个用户
    int addUser(User user);

    //修改用户
    int updateUser(User user);

    //删除用户
    int deleteUser(int id);

}

UserMapper.xml

<?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="com.kakafa.dao.UserMapper">

    <select id="getUserList" resultType="com.kakafa.pojo.User">
        select * from mybatistest.user;
    </select>
    <select id="getUserById" parameterType="int" resultType="com.kakafa.pojo.User">
        select * from mybatistest.user where id = #{id};
    </select>
    <insert id="addUser" parameterType="com.kakafa.pojo.User" >
        insert into mybatistest.user(id,name,pwd) values(#{id},#{name},#{pwd});
    </insert>
    <update id="updateUser" parameterType="com.kakafa.pojo.User">
        update mybatistest.user
        set name=#{name},pwd=#{pwd}
        where id=#{id};
    </update>
    <delete id="deleteUser" parameterType="int">
        delete
        from mybatistest.user
        where id=#{id};
    </delete>

</mapper>

测试 注意：增删改需要提交事务sqlSession.commit();

package com.kakafa.dao;

import com.kakafa.pojo.User;
import com.kakafa.util.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class UserMapperTest {

    @Test
    public void test(){

        //1.获得sqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        //2.执行sql
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);//得到一个UserDao类型的对象
        List<User> userList = mapper.getUserList();
        for (User user : userList) {
            System.out.println(user);
        }
        //关闭sqlSession
        sqlSession.close();
    }

    @Test
    public void getUserById(){

        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        User user = mapper.getUserById(2);
        System.out.println(user);

        sqlSession.close();
    }

    //增删改需要提交事务
    @Test
    public  void addUser(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        User user=new User(3,"张三","123456");

        int i= mapper.addUser(user);
        System.out.println(i);

        //提交事务
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public  void updateUser(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        User user=new User(3,"邓孝慈","111111");

        int i= mapper.updateUser(user);
        System.out.println(i);

        //提交事务
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public  void deleteUser(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        int i= mapper.deleteUser(3);
        System.out.println(i);

        //提交事务
        sqlSession.commit();
        sqlSession.close();
    }

}