MyBatis之二：简单增删改查

时间：2021-05-16 14:58:14

　　这一篇在上一篇的基础上简单讲解如何进行增删改查操作。

　　一、在mybatis的配置文件conf.xml中注册xml与注解映射

<!-- 注册映射文件 -->

    <mappers>

        <!-- 通过xml方式映射 -->

        <mapper resource="com/mybatis/crud/userMapper.xml" />

        <!-- 通过注解方式映射 -->

        <mapper class="com.mybatis.crud.IUserMapper" />

    </mappers>

　　二、在这个com.mybatis.crud包下面新建userMapper.xml文件与IUserMapper接口

　　　　1、userMapper.xml明细如下

<?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">

<mapper namespace="com.mybatis.crud.userMapper">

    <insert id="addUser" parameterType="com.mybatis.crud.User">

        insert into users(id_id,name_n,age_a) values(#{id},#{name},#{age})

    </insert>

    <delete id="deleteUser" parameterType="int">

        delete from users where

        id_id=#{id}

    </delete>

    <update id="updateUser" parameterType="com.mybatis.crud.User">

        update users set

        name_n=#{name},age_a=#{age} where id_id =#{id}

    </update>

    <select id="getAllUsers" resultType="com.mybatis.crud.User"

        resultMap="usermap">

        select *

        from Users

    </select>

    <resultMap type="com.mybatis.crud.User" id="usermap">

        <id property="id" column="id_id" />

        <result property="name" column="name_n" />

        <result property="age" column="age_a" />

    </resultMap>

    <select id="getUser" parameterType="int" resultType="com.mybatis.crud.User"

        resultMap="usermap">

        select *

        from Users where id_id=#{id}

    </select>

</mapper>

　　　　2、IUserMapper接口定义如下

package com.mybatis.crud;

import java.util.List;

import java.util.Properties;

import org.apache.ibatis.annotations.Delete;

import org.apache.ibatis.annotations.Insert;

import org.apache.ibatis.annotations.Result;

import org.apache.ibatis.annotations.Results;

import org.apache.ibatis.annotations.Select;

import org.apache.ibatis.annotations.Update;

import org.apache.ibatis.type.JdbcType;

public interface IUserMapper {

    @Insert("insert into users(id_id,name_n,age_a) values(#{id},#{name},#{age})")

    public int add(User user);

    @Delete("delete from users where id_id=#{id}")

    public int deleteById(int id);

    @Update("update users set name_n=#{name},age_a=#{age} where id_id =#{id}")

    public int update(User user);

    @Select("select * from Users where id_id=#{id}")

    @Results({

            @Result(property = "id", column = "id_id", jdbcType = JdbcType.INTEGER),

            @Result(property = "name", column = "name_n", jdbcType = JdbcType.VARCHAR),

            @Result(property= "age", column = "age_a", jdbcType = JdbcType.INTEGER) })

    public User getById(int id);

    @Select("select * from Users")

    @Results({

        @Result(property = "id", column = "id_id", jdbcType = JdbcType.INTEGER),

        @Result(property = "name", column = "name_n", jdbcType = JdbcType.VARCHAR),

        @Result(property= "age", column = "age_a", jdbcType = JdbcType.INTEGER) })

    public List<User> getAll();

}

　　三、新建一个获取SqlSessionFactory的工具类

package com.mybatis.util;

import java.io.InputStream;

import org.apache.ibatis.session.SqlSessionFactory;

import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import com.mybatis.demo.test;

public class MybatisUtils {

    public static SqlSessionFactory getFactory(){

        String resource = "conf.xml";

        InputStream inputStream = test.class.getClassLoader().getResourceAsStream(resource);

        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        return sessionFactory;

    }

}

　　四、实际测试代码如下

package com.mybatis.crud;

import java.util.List;

import org.apache.ibatis.session.SqlSession;

import org.apache.ibatis.session.SqlSessionFactory;

import org.junit.Test;

import com.mybatis.util.MybatisUtils;

public class TestCrud {

    //方法名称上面F11键 即可运行测试方法

    @Test

    public void testAdd() {

        SqlSessionFactory factory = MybatisUtils.getFactory();

        SqlSession session = factory.openSession(true);

        String statement = "com.mybatis.crud.userMapper.addUser";

        User user1 = new User();

        user1.setId(199);

        user1.setName("wrrrugggcj");

        user1.setAge(296);

        System.out.println("[xml]新增影响行数："+session.insert(statement, user1));

        User user2 = new User();

        user2.setId(198);

        user2.setName("wrrrugggcjeee");

        user2.setAge(26);

        IUserMapper userMapper = session.getMapper(IUserMapper.class);

        System.out.println("[注解]新增影响行数："+userMapper.add( user2));

        session.close();

    }

    @Test

    public void testUpdate() {

        SqlSessionFactory factory = MybatisUtils.getFactory();

        //默认手动提交

        SqlSession session = factory.openSession();

        String statement = "com.mybatis.crud.userMapper.updateUser";

        User user1 = new User();

        user1.setId(199);

        user1.setName("199");

        user1.setAge(89);

        System.out.println("[xml]修改影响行数："+session.update(statement, user1));

        User user2 = new User();

        user2.setId(198);

        user2.setName("198");

        user2.setAge(89);

        IUserMapper userMapper = session.getMapper(IUserMapper.class);

        System.out.println("[注解]修改影响行数："+userMapper.update(user2));

        //提交

        session.commit();

        session.close();

    }

    @Test

    public void testDelete() {

        SqlSessionFactory factory = MybatisUtils.getFactory();

        SqlSession session = factory.openSession(true);

        String statement = "com.mybatis.crud.userMapper.deleteUser";

        System.out.println("[xml]删除影响行数："+session.delete(statement,199)); 

        IUserMapper userMapper = session.getMapper(IUserMapper.class);

        System.out.println("[注解]删除影响行数："+userMapper.deleteById(198)); 

        session.close();

    }

    @Test

    public void testGetAllusers() {

        SqlSessionFactory factory = MybatisUtils.getFactory();

        SqlSession session = factory.openSession(true);

        String statement = "com.mybatis.crud.userMapper.getAllUsers";

        List<User> users = session.selectList(statement);

        System.out.println("[xml]查询用户列表："+users);

        IUserMapper userMapper = session.getMapper(IUserMapper.class);

        System.out.println("[注解]查询用户列表："+userMapper.getAll());

        session.close();

    }

}

　　

　　至此，一个基于mybatis的简单增删改就完成了，不过建议在阅读这篇文章的时候先将入门篇看一遍就可以了。

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