springboot2.x 整合mybatis

1.项目结构搭建

2.相关依赖

        <!--web相关-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--测试相关-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
        </dependency>
        <!-- 实现mybatis的核心 -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>LATEST</version>
        </dependency>
        <!-- jdbc连接mysql的支持-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.25</version>
        </dependency>

3.配置相关

application.peoperties

        <!--web相关-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--测试相关-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
        </dependency>
        <!-- 实现mybatis的核心 -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>LATEST</version>
        </dependency>
        <!-- jdbc连接mysql的支持-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.25</version>
        </dependency>

mybatis-config.xml

<?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">
<configuration>
    <settings>
        <!-- 开启驼峰命名 -->
        <setting name="mapUnderscoreToCamelCase" value="true"/>
        <!-- 打印sql -->
        <!--<setting name="logImpl" value="STDOUT_LOGGING"/>-->
    </settings>
    <!--指定包批量起别名，默认类名（不区分大小写）-->
    <typeAliases>
        <package name="com.example.demo.bean"/>
    </typeAliases>
</configuration>

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.example.demo.dao.UserMapper">
    <!-- 自定义封装规则 -->
    <resultMap id="rm" type="User">
        <id property="id" column="id" javaType="java.lang.Integer" jdbcType="INTEGER"/>
        <result property="name" column="name" javaType="java.lang.String" jdbcType="VARCHAR"/>
        <result property="age" column="age" javaType="java.lang.Integer" jdbcType="INTEGER"/>
    </resultMap>

    <!-- 增 -->
    <insert id="save" parameterType="User">
        insert into user
        <trim prefix="(" suffix=")" suffixOverrides=","><!--前后缀重写用于去除多余的内容-->
            <if test="id != null">
                id,
            </if>
            <if test="name != null">
                name,
            </if>
            <if test="age != null">
                age
            </if>
        </trim>
        <trim prefix="values (" suffix=")" suffixOverrides=",">
            <if test="id != null">
                #{id,jdbcType=INTEGER},
            </if>
            <if test="name != null">
                #{name,jdbcType=VARCHAR},
            </if>
            <if test="age != null">
                #{age,jdbcType=INTEGER},
            </if>
        </trim>
    </insert>

    <!-- 删 -->
    <delete id="deleteById">
        delete from user where id=#{id}
    </delete>

    <!-- 改 --><!--#{}中指定jdbcType可以解决插入空值引起的问题-->
    <update id="update" parameterType="User">
        update user
        <set>
            <if test="name != null">
                name = #{name,jdbcType=VARCHAR},
            </if>
            <if test="age != null">
                age = #{age,jdbcType=INTEGER},
            </if>
        </set>
        where id = #{id,jdbcType=INTEGER}
    </update>

    <!-- 查 -->
    <select id="selectAll" resultMap="rm">
        select * from user
    </select>
    <select id="selectById" resultMap="rm">
        select
        *
        from user
        where id = #{id,jdbcType=INTEGER}
    </select>

</mapper>

4.代码实现

User

package com.example.demo.bean;

public class User {
    private Integer id;
    private String name;
    private Integer age;

    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

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

MybatisUserController

package com.example.demo.controller;

import com.example.demo.bean.User;
import com.example.demo.dao.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
public class MybatisUserController {

    @Autowired
    UserMapper userMapper;

    @GetMapping("/save")
    public String save(){
        System.out.println("[save userMapper]"+userMapper);
        User user=new User();
        user.setName("东哥");
        user.setAge(20);

        int num=userMapper.save(user);
        System.out.println("[insert]"+num);
        return "添加"+num+"条记录";
    }

    @GetMapping("/getAll")
    public List<User> getAll(){
        System.out.println("[getAll userMapper]"+userMapper);
        List<User> users=userMapper.selectAll();
        System.out.println("[select]"+users.size());
        return users;
    }

    @GetMapping("/update")
    public int update(){
        System.out.println("[update userMapper]"+userMapper);
        User update=new User();
        update.setName("xqq3");
        update.setId(5);

        int num = userMapper.update(update);
        System.out.println(num>0?"修改成功":"");
        return num;
    }

    @GetMapping("/delete")
    public int delete(){
        System.out.println("[delete userMapper]"+userMapper);
        int num = userMapper.deleteById(1);
        System.out.println(num>0?"删除成功":"删除失败");
        return num;
    }

    @GetMapping("/getOne")
    public User getOne(){
        System.out.println("[getOne userMapper]"+userMapper);
        User user = userMapper.selectById(2);
        System.out.println(user!=null?"查到1条":"查到0条");
        return user;
    }
}

UserMapper

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package com.example.demo.dao;

import com.example.demo.bean.User;

import java.util.List;

//@Repository
public interface UserMapper {

    int save(User user);//新增用户

    int update(User user);//更新用户信息

    int deleteById(int id);//根据id删除

    User selectById(int id);//根据id查询

    List<User> selectAll();//查询所有用户信息

}

DemoApplication

package com.example.demo;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@MapperScan("com.example.demo.dao") //会注册bean
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

}

基于注解版的，GitHub:https://github.com/atkgc2019wxd/springboot-learning

springboot2.x 整合mybatis

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