SpringBoot integrates Mybatis (entry version)

SpringBoot integrates Mybatis

Basic Information

Technology stack

Spring Boot 2.4.5、Mybatis

Learning purpose

SpringBoot integrates Mybatis

Detailed project

Create a new Spring Initializr project

Create the file structure of the project and select the version of jdk

Select the dependencies required by the project

Modify the project name and click Finish to complete

The pom.xml generated after the project is built

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.4.5</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.malf</groupId>
    <artifactId>springboot_mybatis</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot_mybatis</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.4</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

Modify the configuration file

This article does not use the application.properties file, but uses the more concise application.yml file. Delete the original application.properties file in the resource folder and create the application.yml configuration file (Note: SpringBoot will parse the application.yml file into application.properties at the bottom of SpringBoot). This article creates two yml files (application.yml and application-dev.yml)

application.yml

spring:
  profiles:
    active: dev

application-dev.yml

server:
  port: 8000
mybatis:
  mapper-locations: classpath:mapping/*Mapper.xml
  type-aliases-package: com.malf.entity
#showSql
logging:
  level:
    com:
      example:
        mapper : debug
spring:
  datasource:
    url: jdbc:mysql://localhost:3306/springboot_mybatis?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
    username: root
    password: 123456
    driver-class-name: com.mysql.cj.jdbc.Driver

Database table structure

CREATE TABLE `user` (
  `id` int(32) NOT NULL AUTO_INCREMENT,
  `userName` varchar(32) NOT NULL,
  `passWord` varchar(50) NOT NULL,
  `realName` varchar(32) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

Create entity classes to implement business processes

Create the package controller, entity, dao, service, and create a mapping folder under resources for writing sql statements, or you can write them directly in the mapper file by way of annotations.

entity

package com.malf.entity;

/**
 * @author 巅峰小词典
 * @description
 * @date 2021/5/20
 * @project springboot_mybatis
 */
public class User {

    private Integer id;
    private String userName;
    private String passWord;
    private String realName;

    public Integer getId() {
        return id;
    }

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

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getPassWord() {
        return passWord;
    }

    public void setPassWord(String passWord) {
        this.passWord = passWord;
    }

    public String getRealName() {
        return realName;
    }

    public void setRealName(String realName) {
        this.realName = realName;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", userName='" + userName + '\'' +
                ", passWord='" + passWord + '\'' +
                ", realName='" + realName + '\'' +
                '}';
    }

}

controller

package com.malf.controller;

import com.malf.service.UserService;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;

/**
 * @author 巅峰小词典
 * @description
 * @date 2021/5/20
 * @project springboot_mybatis
 */
@RestController
@RequestMapping("/user")
public class UserController {

    @Resource
    private UserService userService;

    @RequestMapping("getUser/{id}")
    public String GetUser(@PathVariable int id) {
        return userService.selectById(id).toString();
    }

}

dao

package com.malf.dao;

import com.malf.entity.User;
import org.springframework.stereotype.Repository;

/**
 * @author 巅峰小词典
 * @description
 * @date 2021/5/20
 * @project springboot_mybatis
 */
@Repository
public interface UserMapper {

    User selectById(int id);

}

service

package com.malf.service;

import com.malf.entity.User;

/**
 * @author 巅峰小词典
 * @description
 * @date 2021/5/20
 * @project springboot_mybatis
 */
public interface UserService {

    public User selectById(int id);

}

service.impl

package com.malf.service.impl;

import com.malf.entity.User;
import com.malf.dao.UserMapper;
import com.malf.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;

/**
 * @author 巅峰小词典
 * @description
 * @date 2021/5/20
 * @project springboot_mybatis
 */
@Service
public class UserServiceImpl implements UserService {

    @Resource
    UserMapper userMapper;

    public User selectById(int id){
        return userMapper.selectById(id);
    }

}

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.malf.dao.UserMapper">
    <resultMap type="com.malf.entity.User" id="User">
        <result column="id" jdbcType="INTEGER" property="id"/>
        <result column="userName" jdbcType="VARCHAR" property="userName"/>
        <result column="passWord" jdbcType="VARCHAR" property="passWord"/>
        <result column="realName" jdbcType="VARCHAR" property="realName"/>
    </resultMap>
    <select id="selectById" resultType="com.malf.entity.User">
        select * from user where id = #{id}
  </select>
</mapper>

Final frame structure

Add an annotation in the startup class to give the mapper file path that needs to be scanned @MapperScan("com.malf.dao")

package com.malf;

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

@SpringBootApplication
@MapperScan("com.malf.dao") // 扫描的mapper
public class SpringbootMybatisApplication {

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

}

Finally start, the browser enters the address: `http://localhost:8000/user/getUser/1`

The test is successful, and SpringBoot integrates the basic framework of Mybatis to build successfully.

Source reference

springboot_mybatis

SpringBoot integrates Mybatis (entry version)