Springboot与MyBatis-Plus整合开发基础

官网的入门案例缺失和过时的东西太多,本文进行了纠正，并增加了ISerivce的使用入门

秦皇岛开埠码头-2021年7月21日.jpg

1. pom.xml

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>org.example</groupId>
    <artifactId>mybatis-plus-demo</artifactId>
    <version>1.0-SNAPSHOT</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.3</version>
        <relativePath/>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.3.1</version>
        </dependency>
    </dependencies>
</project>

2. application.yml:

spring:
  datasource:
    driver-class-name: org.h2.Driver
    url: jdbc:h2:mem:test
    username: root
    password: test
  sql:
    init:
      schema-locations:
        - classpath:db/schema-h2.sql
      data-locations:
        - classpath:db/data-h2.sql

3. schema-h2.sql和data-h2.sql，使用自动增长主键，方便后期测试使用

db/schema-h2.sql:

DROP TABLE IF EXISTS user;

CREATE TABLE user
(
    id BIGINT(20) NOT NULL AUTO_INCREMENT COMMENT '自动生成主键',
    name VARCHAR(30) NULL DEFAULT NULL COMMENT '姓名',
    age INT(11) NULL DEFAULT NULL COMMENT '年龄',
    email VARCHAR(50) NULL DEFAULT NULL COMMENT '邮箱',
    PRIMARY KEY (id)
);

db/data-h2.sql:

DELETE FROM user;

INSERT INTO user (name, age, email) VALUES
('John', 100, 'test1@baomidou.com'),
('Jack', 20, 'test2@baomidou.com'),
('Tom', 28, 'test3@baomidou.com'),
('Sandy', 21, 'test4@baomidou.com'),
('Billie', 24, 'test5@baomidou.com');

4. cn.johnyu.pojo.User

package cn.johnyu.pojo;
import lombok.Data;

@Data
public class User {
    private Long id;
    private String name;
    private Integer age;
    private String email;
}

4. cn.johnyu.mapper.UserMapper

package cn.johnyu.mapper;

import cn.johnyu.pojo.User;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.springframework.stereotype.Component;

@Component
public interface UserMapper extends BaseMapper<User> {

}

5. 引导类：

package cn.johnyu;

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

@SpringBootApplication
@MapperScan("cn.johnyu.mapper")
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

}

5. cn.johnyu.service.UserService

CURD核心功能: https://baomidou.com/guide/crud-interface.html

import cn.johnyu.mapper.UserMapper;
import cn.johnyu.pojo.User;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.stereotype.Service;

//ServiceImpl是IService的实现类，同时注入了UserMapper
@Service
public class UserService extends ServiceImpl<UserMapper, User>{
//    自动注入UserMapper对象
//    以下代码是代理生成的，可以不必硬编码
//    @Autowired
//    private BaseMapper<User> baseMapper;
}

6. 测试类：

package cn.johnyu;

import cn.johnyu.mapper.UserMapper;
import cn.johnyu.pojo.User;
import cn.johnyu.service.UserService;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import static org.junit.jupiter.api.Assertions.*;
import java.util.List;

@SpringBootTest
public class SampleTest {
    @Autowired
    private UserMapper userMapper;
    @Autowired
    private UserService userService;
    @Test
    public void testSelect() {
        System.out.println(("----- selectAll method test ------"));
        List<User> userList = userMapper.selectList(null);

        assertEquals(5, userList.size());
        userList.forEach(System.out::println);
    }
    @Test
    public void testSelect2() {
        User user= userService.getById(1);
        assertEquals(user.getName(),"John");
    }
}