SpringBoot框架中Mybatis-plus的简单使用操作汇总

spring.datasource.driver- class -name=com.mysql.cj.jdbc.Driver

spring.datasource.url=jdbc:mysql: //localhost:3306/cat_house?serverTimezone=GMT%2B8

spring.datasource.username=username

spring.datasource.password=password

# mybatis日志（控制台能显示SQL语句）

mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

<!-- mybatis驱动 -->

<dependency>

     <groupId>com.baomidou</groupId>

     <artifactId>mybatis-plus-boot-starter</artifactId>

     <version> 3.0 . 5 </version>

</dependency>

<!-- 数据库驱动 -->

<dependency>

     <groupId>mysql</groupId>

     <artifactId>mysql-connector-java</artifactId>

</dependency>

<!-- lombok用来简化实体类 -->

<dependency>

     <groupId>org.projectlombok</groupId>

     <artifactId>lombok</artifactId>

</dependency>

package com.xsha.boot.entity;

import lombok.Data;

@Data

public class Topic {

     private int id;

     private String title;

     private String time;

     private int count;

     private int version;

}

package com.xsha.boot.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;

import com.xsha.boot.entity.Topic;

import org.springframework.stereotype.Repository;

@Repository

public interface TopicMapper extends BaseMapper<Topic> {

}

package com.xsha.boot;

import com.xsha.boot.entity.Topic;

import com.xsha.boot.mapper.TopicMapper;

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;

@SpringBootTest

public class MainApplicationTest {

     @Autowired

     // 可在指定的接口上添加注解Repository，就不会爆红了

     private TopicMapper topicMapper;

     // 查询所有数据

     @Test

     public void findAll() {

         List<Topic> topics = topicMapper.selectList( null );

         for ( int i = 0 ; i < topics.size(); i++) {

             System.out.println(topics.get(i));

         }

     }

     // 添加操作

     public void addTopic() {

//        SimpleDateFormat ft = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");

//        Date date = new Date();

         Topic topic = new Topic();

         topic.setTitle( "SSM框架整合了哪些主流框架" );

         // 时间的添加可以采用mybatis-plus框架实现，可查看Controller中接口实现和实体类属性的注解

//        topic.setTime(ft.format(date));

         int row = topicMapper.insert(topic);

         System.out.println( "添加的行数：" +row);

     // 修改操作

     public void updateTopic() {

         topic.setId( 20 );

         topic.setCount( 10 );

         int row = topicMapper.updateById(topic);

         System.out.println( "修改的行数" +row);

}

// 可以在id属性上添加TableId注解可以修改id唯一键值的策略（自动填充），如@TableId(type=IdType.AUTO)

// @TableId(type=IdType.ID_WORKER) 生成19位唯一数字的键值

// @TableId(type=IdType.ID_WORKER_STR) 生成19位唯一字符串的键值

private int id;

// 采用mybatis-plus框架的策略自动填充时间

// @TableField(fill=FieldFill.INSERT)  表示自动填充创建时间

// @TableField(fill=FieldFill.INSERT_UPDATE) 表示自动填充更新时间

@TableField (fill = FieldFill.INSERT)

private String time;

package com.xsha.boot.controller;

import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;

import org.apache.ibatis.reflection.MetaObject;

import org.springframework.stereotype.Component;

import java.text.SimpleDateFormat;

import java.util.Date;

@Component

public class MyMetaObjectController implements MetaObjectHandler {

     // 使用mybatis-plus实现添加操作，这个方法自动调用

     @Override

     public void insertFill(MetaObject metaObject) {

         SimpleDateFormat ft = new SimpleDateFormat( "yyyy-MM-dd hh:mm:ss" );

         Date date = new Date();

         // 第一个参数不是表格的字段名称，而是实体类的属性名称

         this .setFieldValByName( "time" , ft.format(date), metaObject);

     }

     // 使用mybatis-plus实现更新操作，这个方法自动调用

     public void updateFill(MetaObject metaObject) {

         // 更新时间可根据需求实现

}

@Configuration

@MapperScan ( "com.xsha.boot.mapper" )

public class MyConfig {

     // 乐观锁插件

     @Bean

     public OptimisticLockerInterceptor optimisticLockerInterceptor() {

         return new OptimisticLockerInterceptor();

     }

}

// 单个id查询

@Test

public void selectTopic() {

     Topic topic = topicMapper.selectById( 20 );

     System.out.println(topic);

}

// 多个id批量查询

@Test

public void selectTopics() {

     List<Topic> topics = topicMapper.selectBatchIds(Arrays.asList( 1 , 2 , 3 , 4 ));

     for ( int i = 0 ; i < topics.size(); i++) {

         System.out.println(topics.get(i));

     }

}

// 分页插件

@Bean

public PaginationInterceptor paginationInterceptor() {

     return new PaginationInterceptor();

}

// 分页查询

@Test

public void selectByPage() {

     // 1.创建page对象，传递当前页和每页记录数的两个参数

     Page<Topic> page = new Page<>( 1 , 3 );

     // 2.调用mybatis-plus分页查询的方法，把分页所有的数据封装到page对象里面，第二个参数是条件

     topicMapper.selectPage(page, null );

     // 3.通过page对象获取分页数据

     System.out.println(page.getCurrent());  // 当前页

     System.out.println(page.getRecords());  // 每页数据list集合

     System.out.println(page.getSize());  // 每页显示记录数

     System.out.println(page.getTotal());  // 总记录数

     System.out.println(page.getPages());  // 总页数

     System.out.println(page.hasNext());  // 是否有下一页

     System.out.println(page.hasPrevious());  // 是否有上一页

}

// 单个id删除

    @Test

    public void deleteTopic() {

        int row = topicMapper.deleteById( 20 );

        System.out.println(row);

    }

    // 多个id批量删除

    @Test

    public void deleteTopics() {

        int rows = topicMapper.deleteBatchIds(Arrays.asList( 1 , 2 , 3 , 4 ));

        System.out.println(rows);

    }

@TableLogic

private int delete;

// 逻辑删除插件

@Bean

public ISqlInjector sqlInjector() {

     return new LogicSqlInjector();

}

# 逻辑删除与否的默认值

mybatis-plus.global-config.db-config.logic-delete-value= 1

mybatis-plus.global-config.db-config.logic-not-delete-value= 0

// 逻辑删除

@Test

public void logicDeleteTopic() {

     int row = topicMapper.deleteById( 21 );

     System.out.println(row);

}

/**

  * SQL执行性能分析插件

  * 开发环境使用，线上不推荐。maxTime指的是sql最大执行时长

  *

  * 三种环境：dev开发环境、test测试环境、prod生成环境

  * @return

  */

@Bean

@Profile ({ "dev" , "test" })   // 设置dev，test的环境开启

public PerformanceInterceptor performanceInterceptor() {

     PerformanceInterceptor performanceInterceptor = new PerformanceInterceptor();

     performanceInterceptor.setMaxTime( 100 ); // 数值单位为毫秒ms

     performanceInterceptor.setFormat( true );

     return performanceInterceptor;

}

# 环境设置:dev  test  prod

spring.profiles.active=dev

// mybatis-plus实现复杂查询

@Test

public void querySelect() {

     // 1.创建QueryWrapper对象

     QueryWrapper<Topic> queryWrapper = new QueryWrapper<>();

     // 2.通过QueryWrapper设置条件

     // ge(>=)、gt(>)、le(<=)、lt(<)

     queryWrapper.ge( "count" , 3 );

     List<Topic> topics1 = topicMapper.selectList(queryWrapper);

     System.out.println( "FIRST" );

     System.out.println(topics1);

     // eq(==)、ne(!=)

     queryWrapper.ne( "deleted" , 0 );

     List<Topic> topics2 = topicMapper.selectList(queryWrapper);

     System.out.println( "SECOND" );

     System.out.println(topics2);

     // between(在···和···之间)

     queryWrapper.between( "time" , "2021-10-12 07:05:29.546779" , "2021-10-27 15:02:09.458571" );

     List<Topic> topics3 = topicMapper.selectList(queryWrapper);

     System.out.println( "THIRD" );

     System.out.println(topics3);

     // like(模糊查询)

     queryWrapper.like( "title" , "SSM" );

     List<Topic> topics4 = topicMapper.selectList(queryWrapper);

     System.out.println( "FORTH" );

     System.out.println(topics4);

     // 排序 orderByDesc   orderByAsc

     queryWrapper.orderByDesc( "count" );

     List<Topic> topics5 = topicMapper.selectList(queryWrapper);

     System.out.println( "FIFTH" );

     System.out.println(topics5);

     // 指定要查询的列 last拼接sql语句

     queryWrapper.select( "id" , "title" , "count" );

     queryWrapper.last( "limit 2" );

     List<Topic> topics6 = topicMapper.selectList(queryWrapper);

     System.out.println( "SIXTH" );

     System.out.println(topics6);

}