MyBatis-Plus--分页时的排序--方法/教程/实例

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简介

​说明​

本文用示例介绍MyBtisPlus分页时排序的方法。

​分页时排序的方法​

1. 后端OrderItems排序
2. 后端Wrapper排序
3. 前端指定排序

​排序涉及到的类​

排序涉及到Page类的List<OrderItem> orders;成员，OrderItem定义如下：

public class OrderItem implements Serializable {
    private static final long serialVersionUID = 1L;

    //需要进行排序的字段
    private String column;

    // 是否正序排列，默认 true
    private boolean asc = true;
    ...
}

建库建表

DROP DATABASE IF EXISTS mp;
CREATE DATABASE mp DEFAULT CHARACTER SET utf8;
USE mp;

DROP TABLE IF EXISTS `t_user`;
SET NAMES utf8mb4;

CREATE TABLE `t_user`
(
    `id`           BIGINT(0) NOT NULL AUTO_INCREMENT,
    `user_name`    VARCHAR(64) NOT NULL COMMENT '用户名（不能重复）',
    `nick_name`    VARCHAR(64) NULL COMMENT '昵称（可以重复）',
    `email`        VARCHAR(64) COMMENT '邮箱',
    `create_time`  DATETIME(0) NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
    `update_time`  DATETIME(0) NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '修改时间',
    `deleted_flag` BIGINT(0) NOT NULL DEFAULT 0 COMMENT '0：未删除 其他：已删除',
    PRIMARY KEY (`id`) USING BTREE,
    UNIQUE KEY `index_user_name_deleted_flag` (`user_name`, `deleted_flag`),
    KEY `index_create_time`(`create_time`)
) ENGINE = InnoDB COMMENT = '用户';

INSERT INTO `t_user` VALUES (1, 'knife', '刀刃', '[e-mail]', '2021-01-23 09:33:36', '2021-01-23 09:33:36', 0);
INSERT INTO `t_user` VALUES (2, 'sky', '天蓝', '[e-mail]', '2021-01-24 18:12:21', '2021-01-24 18:12:21', 0);

执行后的结果：

依赖

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 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>2.3.12.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>MyBatis-Plus_Simple</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>MyBatis-Plus_Simple</name>
    <description>Demo project for Spring Boot</description>

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

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

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.5.1</version>
        </dependency>

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

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

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

        <dependency>
            <groupId>com.github.xiaoymin</groupId>
            <artifactId>knife4j-spring-boot-starter</artifactId>
            <version>3.0.3</version>
        </dependency>

    </dependencies>

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

</project>

配置

​application.yml​

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/mp?characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
    username: root
    password: 222333

#mybatis-plus配置控制台打印完整带参数SQL语句
mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

​分页插件的配置（必须）​

package com.example.demo.config;

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
 
@Configuration
public class MyBatisPlusConfig {

    /**
     * 分页插件
     */
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
        return interceptor;
    }
}

代码

Entity

package com.example.demo.user.entity;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableLogic;
import com.baomidou.mybatisplus.annotation.TableName;
import com.baomidou.mybatisplus.extension.activerecord.Model;
import lombok.Data;

import java.time.LocalDateTime;

@Data
@TableName(value = "t_user")
public class User {
    @TableId(value = "id", type = IdType.AUTO)
    private Long id;

    /**
     * 用户名（不能重复）
     */
    private String userName;

    /**
     * 昵称（可以重复）
     */
    private String nickName;

    /**
     * 邮箱
     */
    private String email;

    /**
     * 创建时间
     */
    private LocalDateTime createTime;

    /**
     * 修改时间
     */
    private LocalDateTime updateTime;

    /**
     * 0：未删除 其他：已删除
     */
    @TableLogic(delval = "id")
    private Long deletedFlag;
}

Service

​接口​

package com.example.demo.user.service;

import com.baomidou.mybatisplus.extension.service.IService;
import com.example.demo.user.entity.User;

public interface UserService extends IService<User> {
}

​实现​

package com.example.demo.user.service.impl;

import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.example.demo.user.entity.User;
import com.example.demo.user.mapper.UserMapper;
import com.example.demo.user.service.UserService;
import org.springframework.stereotype.Service;

@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService {
}

Controller

package com.example.demo.user.controller;

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.core.metadata.OrderItem;
import com.baomidou.mybatisplus.core.toolkit.Wrappers;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.example.demo.user.entity.User;
import com.example.demo.user.service.UserService;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@Api(tags = "排序")
@RestController
@RequestMapping("sort")
public class SortController {

    @Autowired
    private UserService userService;

    @ApiOperation("默认顺序")
    @GetMapping("defaultOrder")
    public IPage<User> defaultOrder(Page<User> page) {
        return userService.page(page);
    }

    @ApiOperation("通过orderItems")
    @GetMapping("orderItems")
    public IPage<User> orderItems(Page<User> page) {
        page.addOrder(OrderItem.desc("create_time"));
        // 可以指定多列。比如下边这个：按create_time排序，若create_time相同，则按id排序
        // page.addOrder(OrderItem.desc("create_time"), OrderItem.asc("id"));
        return userService.page(page);
    }

    @ApiOperation("通过wrapper")
    @GetMapping("wrapper")
    public IPage<User> wrapper(Page<User> page) {
        LambdaQueryWrapper<User> queryWrapper = Wrappers.<User>lambdaQuery();
        // 按create_time排序，若create_time相同，则按id排序
        queryWrapper.orderByDesc(User::getCreateTime);
        queryWrapper.orderByAsc(User::getId);
        return userService.page(page, queryWrapper);
    }

    @ApiOperation("前端指定顺序")
    @GetMapping("byFrontEnd")
    public IPage<User> byFrontEnd(Page<User> page) {
        return userService.page(page);
    }
}

测试

访问Knife4j页面：​​http://localhost:8080/doc.html​​

​1.不指定顺序​

本处前端不传任何参数进行的测试。

​2.后端OrderItem排序（create_time倒序）​

本处前端不传任何参数进行的测试。

​3.后端Wrapper排序（create_time倒序，id升序）​

本处前端不传任何参数进行的测试。

​4.前端指定排序（create_time倒序）​

前端指定orders[0].asc和orders[0].column

结果：