mp相关配置文件

package com.nanfeng.getdata.config;

import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class PageConfig {

    /**
     * 3.4.0之前的版本用这个
     * @return
     */
   /* @Bean
    public PaginationInterceptor paginationInterceptor(){
        return  new PaginationInterceptor();
    }*/

    /**
     * 3.4.0之后提供的拦截器的配置方式
     *
     * @return
     */
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor());
        return mybatisPlusInterceptor;
    }
}

　　

package com.nanfeng.getdata;

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

@SpringBootApplication
@MapperScan("com.nanfeng.getdata.mapper")
public class GetdataApplication {

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

}

package com.nanfeng.getdata.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.nanfeng.getdata.entity.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;

@Mapper
public interface UserMapper extends BaseMapper<User> {
    /**
     * 这个sql写的有问题,mp实现多表操作其实就是这样实现的(或者建立xml映射文件)
     * @return
     */

    //@Select("select name, age from tb1,tb2 where id=1")
   // public User selectManyTable();
}

# datasource
spring:
  datasource:
    url: jdbc:mysql:///mptest
    username: root
    password: root
    driver-class-name: com.mysql.jdbc.Driver


mybatis-plus:
  global-config:
    db-config:
      # 表名前缀
      table-prefix: tb_
      # id生成策略 数据库自增
      #id-type: auto
  #configuration:
    # 日志
    #log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
    # 枚举包
  #type-enums-package: com.itheima.mp.enums

package com.itheima.mp;

import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.itheima.mp.entity.User;
import com.itheima.mp.mapper.UserMapper;
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.HashMap;
import java.util.List;
import java.util.Map;

@SpringBootTest
@RunWith(SpringRunner.class)
class UserMapperTest {

    @Autowired
    private UserMapper userMapper;


    /**
     * 根据id查询
     */
    @Test
    public void testSelectById() {

        User user = userMapper.selectById("1");
        System.out.println(user);


    }



    /**
     * 添加
     */
    @Test
    public void testInsert() {

        User user = new User();

        user.setId("666666666");
        //user.setUserName("itcast");
        //user.setPassword("itheima");

        int count = userMapper.insert(user);
        System.out.println(count);


    }
    /**
     * 删除
     */
    @Test
    public void testDelete() {

/*

        //1. 根据id删除
        int count = userMapper.deleteById(8L);

*/
/*
        //2. 根据id集合批量删除
        List ids = new ArrayList();
        ids.add(6);
        ids.add(7);
        userMapper.deleteBatchIds(ids);
*/
        //3. 根据map构造条件，删除

        Map<String, Object> map = new HashMap<>();

        //delete from tb_user where user_name = ? and age = ?
        map.put("user_name","zhangsan");
        map.put("age","18");
        userMapper.deleteByMap(map);




    }


    /**
     * 修改
     */
    @Test
    public void testUpdateById() {

        User user = new User();
        //user.setId(2L);
        //user.setPassword("1111111");

        int count = userMapper.updateById(user);
    }


    /**
     * 分页查询：
     *  1. 当前页码：currentPage
     *  2. 每页显示条数：size
     *
     *  注意：使用mp的分页要设置一个拦截器！！！
            */
    @Test
    public void testSelectPage() {
        int current = 1;//当前页码
        int size = 2;//每页显示条数
        IPage<User> page = new Page(current,size);
        userMapper.selectPage(page,null);


        List<User> records = page.getRecords();//当前页的数据
        long pages = page.getPages();//总页数 2
        long total = page.getTotal();//总记录数 4

        System.out.println(records);
        System.out.println(pages);
        System.out.println(total);
    }
}

<?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>2.3.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.itheima</groupId>
    <artifactId>mybatis_plus_springboot</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>mybatis_plus_springboot</name>


    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.26</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </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>3.4.0</version>
        </dependency>

    </dependencies>

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

</project>