SpringBoot+mybatis plus 框架搭建

1、引入引用

<?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>2.6.2</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.ymn</groupId>
    <artifactId>mybatis003</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>mybatis003</name>
    <description>mybatis003</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <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.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.3.4</version>
        </dependency>
        <!-- 导入mysql -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>RELEASE</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.1</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

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

</project>

　　2、配置数据库连接地址

# DataSource Config
server:
  port: 8099
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/mybatisplus02?autoRe
connect=true&useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=CONVERT_TO_NULL&useSSL=false&nullCatalogMeansCurrent=true
    username: root
    password: 545456546546

　3、创建mapper

@Component
public interface UserMapper  extends BaseMapper<User> {


}

4、创建service访问

@Component
public interface UserMapper  extends BaseMapper<User> {


}

　　

5、单元测试测试

package com.ymn.mybatis003;

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.ymn.mybatis003.entitys.User;
import com.ymn.mybatis003.mappers.UserMapper;
import com.ymn.mybatis003.services.UserService;
import org.junit.Assert;
import org.junit.jupiter.api.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;


import java.util.List;
//有了@RunWith(SpringRunner.class)这些类才能实例化到spring容器中，自动注入才能生效，
@RunWith(SpringRunner.class)
@SpringBootTest
class Mybatis003ApplicationTests {

    @Autowired
    private UserMapper userMapper;

    @Autowired
    private UserService userService;

    @Test
    public void testSelect() {
        System.out.println(("----- selectAll method test ------"));
        List<User> userList = userMapper.selectList(null);
        //Assert.assertEquals(5, userList.size());
        userList.forEach(System.out::println);
        userList.get(0).setName("王五77");
        //Update name by id
        userMapper.updateById(userList.get(0));

        //query user by id
        User user = userMapper.selectById(4);
        System.out.println("编号为4的用户："+user.getName());

        //use wrapper query
        QueryWrapper<User>  queryWrapper = new QueryWrapper<>();
        queryWrapper.eq("id",5);
        User user5 = userMapper.selectOne(queryWrapper);
        System.out.println("第五名用户");
        System.out.println(user5);

        //query count
        QueryWrapper<User> queryWrapper1 = new QueryWrapper<>();
        queryWrapper1.gt("age",10);
        Long count = userMapper.selectCount(queryWrapper1);
        System.out.println("大于10岁的用户数："+count);

        User user3 = userService.getById(1);
        System.out.println("使用service获取对象");
        System.out.println(user3);

        LambdaQueryWrapper<User> lamadaQueryWrapper = new LambdaQueryWrapper<>();
        lamadaQueryWrapper.eq(User::getId,9);
        User user9 = userService.getOne(lamadaQueryWrapper);
        System.out.println("第九个用户的名称："+user9.getName());

    }



}


6、sql语句