mybatis之增删改查

• 核心配置文件中配置数据库连接及注册mapper.xml
• mapper.xml用来编写执行的sql（namespace为对应的接口类，标签id为接口类中的方法名）
• User为实体对象类
• UserDao为接口类（操作对象类）

核心配置文件

<?xml version="1.0" encoding="UTF8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<!--核心配置文件-->
<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF8&amp;serverTimezone=UTC"/>
                <property name="username" value="root"/>
                <property name="password" value="admin#1234"/>
            </dataSource>
        </environment>
    </environments>
<!--每一个Mapper.xml都需要在Mybatis核心配置文件中注册-->
    <mappers>
        <mapper resource="com\yeyue\dao\UserMapper.xml"/>
    </mappers>
</configuration>

UserMapper.xml

<?xml version="1.0" encoding="UTF8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--namespace:绑定一个对应的Dao/Mapper接口-->
<mapper namespace="com.yeyue.dao.UserDao">
<!--    获取所有用户-->
    <select id="getUserList" resultType="com.yeyue.pojo.User">
        select * from mybatis.user;
    </select>
<!--通过id查看用户-->
    <select id="getUserById" resultType="com.yeyue.pojo.User" parameterType="int">
        select * from mybatis.user where id = #{id};
    </select>
<!--新增用户-->
    <insert id="addUser" parameterType="com.yeyue.pojo.User" >
        insert into mybatis.user (id,name,pwd) values (#{id},#{name},#{pwd});
    </insert>
<!--更新用户-->
    <update id="updateUserById" parameterType="com.yeyue.pojo.User" >
        update mybatis.user set pwd = #{pwd} where id = #{id};
    </update>
<!--删除用户-->
    <delete id="deleteUserById" parameterType="com.yeyue.pojo.User">
        delete from mybatis.user where id = #{id} ;
    </delete>
</mapper>

User

package com.yeyue.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 String getName() {
        return name;
    }

    public String getPwd() {
        return pwd;
    }

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

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

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

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

UserDao

package com.yeyue.dao;

import com.yeyue.pojo.User;

import java.util.List;

public interface UserDao {
    //获取所有用户
    List<User> getUserList();
    //根据id查找用户
    User getUserById(int id);
    //新增用户
    int addUser(User user);
    //更新用户
    int updateUserById(User user);
    //删除用户
    int deleteUserById(User user);
}

测试类

package com.yeyue.dao;

import com.yeyue.pojo.User;
import com.yeyue.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class UserDaoTest {
    @Test
    public void test() {
        //获得session对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        try {
            //执行sql  方式一
            UserDao mapper = sqlSession.getMapper(UserDao.class);
            List<User> userList = mapper.getUserList();

            //方式二 不推荐
            //List<User> userList = sqlSession.selectList("com.yeyue.dao.UserDao.getUserList");

            for (User user : userList) {
                System.out.println(user);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //关闭session
            sqlSession.close();
        }
    }
    @Test
    public void test2() {
        //获得session对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        try {
            UserDao mapper = sqlSession.getMapper(UserDao.class);
            User user = mapper.getUserById(1);

            System.out.println(user);

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //关闭session
            sqlSession.close();
        }
    }
    @Test
    public void test3() {
        //获得session对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        try {
            UserDao mapper = sqlSession.getMapper(UserDao.class);
            int i = mapper.addUser(new User(5,"你好吗","1214888133"));
            if(i>0){
                System.out.println("插入成功");
            }

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //提交事务
            sqlSession.commit();
            //关闭session
            sqlSession.close();
        }
    }
    @Test
    public void test4() {
        //获得session对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        try {
            UserDao mapper = sqlSession.getMapper(UserDao.class);
            int i = mapper.updateUserById(new User(1,"么么哒","888888"));
            if(i>0){
                System.out.println("更新成功");
            }

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //提交事务
            sqlSession.commit();
            //关闭session
            sqlSession.close();
        }
    }
    @Test
    public void test5() {
        //获得session对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        try {
            UserDao mapper = sqlSession.getMapper(UserDao.class);
            int i = mapper.deleteUserById(new User(5,"张三","888888"));
            System.out.println(i);
            if(i>0){
                System.out.println("删除成功");
            }

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //提交事务
            sqlSession.commit();
            //关闭session
            sqlSession.close();
        }
    }
}