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一、创建Maven工程

二、pom.xml文件

引入 MyBatis Plus 的依赖，

   
       
    
     4.0.0
        
            
     
      org.springframework.boot
             
     
      spring-boot-starter-parent
             
     
      2.3.4.RELEASE
             
      
         
        
    
     com.md
        
    
     01-hello
        
    
     0.0.1-SNAPSHOT
        
    
     01-hello
        
    
     Demo project for Spring Boot
        
            
     
      1.8
         
        
            
                 
      
       org.springframework.boot
                  
      
       spring-boot-starter-thymeleaf
              
             
                 
      
       org.springframework.boot
                  
      
       spring-boot-starter-web
              
     
             
                 
      
       mysql
                  
      
       mysql-connector-java
                  
      
       5.1.9
              
             
             
                 
      
       com.baomidou
                  
      
       mybatis-plus-boot-starter
                  
      
       3.3.1.tmp
              
             
                 
      
       org.projectlombok
                  
      
       lombok
                  
      
       true
              
             
                 
      
       org.springframework.boot
                  
      
       spring-boot-starter-test
                  
      
       test
                  
                      
                           
        
         org.junit.vintage
                            
        
         junit-vintage-engine
                        
                   
              
         
        
            
                 
                      
       
        org.springframework.boot
                       
       
        spring-boot-maven-plugin
                   
              
         
    
   

三、创建实体类

首先数据库中有对应的字段

通过lombok

package com.md.entity;import lombok.Data;/** * @author md * @Desc * @date 2020/10/26 15:38 */// 2. 使用这个注解直接生成set和get方法@Datapublic class Student {    private Integer id;    private String name;    private Integer age;}

四、Mapper接口

package com.md.mapper;import com.baomidou.mybatisplus.core.mapper.BaseMapper;import com.md.entity.Student;/** * @author md * @Desc * @date 2020/10/26 15:46 */// 3. 接口继承BaseMapper并指定类型public interface StudentMapper extends BaseMapper
   
     {}
   

五、主配置

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driverspring.datasource.url=jdbc:mysql://localhost:3306/springboot?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=UTF-8spring.datasource.username=rootspring.datasource.password=123456# 专门用于打印日志mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

六、启动类

package com.md;import org.mybatis.spring.annotation.MapperScan;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication// 4. mapper扫描@MapperScan("com.md.mapper")public class Application {    public static void main(String[] args) {        SpringApplication.run(Application.class, args);    }}

七、测试

package com.md;import com.md.mapper.StudentMapper;import org.junit.jupiter.api.Test;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.test.context.SpringBootTest;@SpringBootTestclass ApplicationTests {    @Autowired    private StudentMapper mapper;    // 5. 测试，查询数据    @Test    void contextLoads() {        // 不加条件全部查询，把每个对象迭代出来        mapper.selectList(null).forEach(System.out::println);    }}

这样就可以把对应的数据查询出来了

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