目录

简介建库建表依赖配置代码EntityMapperServiceController测试

简介

本文介绍MyBatis-Plus的分页的方法。

包括：

不传参数时的默认结果查询不存在的数据手动包装page自定义SQL

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", "abc@qq.com", "2021-01-23 09:33:36", "2021-01-23 09:33:36", 0);
INSERT INTO `t_user` VALUES (2, "sky", "天蓝", "123@qq.com", "2021-01-24 18:12:21", "2021-01-24 18:12:21", 0);

依赖

    4.0.0
    
        org.springframework.boot
        spring-boot-starter-parent
        2.3.12.RELEASE
         
    
    com.example
    MyBatis-Plus_Simple
    0.0.1-SNAPSHOT
    MyBatis-Plus_Simple
    Demo project for Spring Boot
 
    
        1.8
    
 
    
        
            org.springframework.boot
            spring-boot-starter-web
        
 
        
            com.baomidou
            mybatis-plus-boot-starter
            3.5.1
        
 
        
            org.springframework.boot
            spring-boot-starter-test
            test
        
 
        
            mysql
            mysql-connector-java
        
 
        
            org.projectlombok
            lombok
        
 
        
            com.github.xiaoymin
            knife4j-spring-boot-starter
            3.0.3
        
 
    
 
    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
            
        
    
 

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;
}

Mapper

package com.example.demo.user.mapper;
 
import com.baomidou.mybatisplus.core.conditions.Wrapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.core.toolkit.Constants;
import com.example.demo.user.entity.User;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
import org.springframework.stereotype.Repository;
 
@Repository
public interface UserMapper extends BaseMapper {
    @Select("SELECT * FROM t_user ${ew.customSqlSegment}")
    IPage findUser(IPage page, @Param(Constants.WRAPPER) Wrapper wrapper);
}

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 {
}

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 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.toolkit.Wrappers;
import com.baomidou.mybatisplus.extension.conditions.query.LambdaQueryChainWrapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.example.demo.user.entity.User;
import com.example.demo.user.mapper.UserMapper;
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 = "分页")
@RestController
@RequestMapping("page")
public class PageController {
 
    @Autowired
    private UserService userService;
 
    // 我为了简单直接注入mapper，项目中controller要通过service调mapper
    @Autowired
    private UserMapper userMapper;
 
    @ApiOperation("不传参数")
    @GetMapping("noParam")
    public IPage noParam(Page page) {
        return userService.page(page);
    }
 
    @ApiOperation("查不存在的数据")
    @GetMapping("notExist")
    public IPage notExist(Page page) {
        // 如果查出来为空，会返回入参page里边的数据，比如：current，size等。不需要自己判空。
        return userService.lambdaQuery()
                .eq(User::getUserName, "abcd")
                .page(page);
    }
 
    @ApiOperation("手动包装")
    @GetMapping("manualPack")
    public IPage manualPack(Page page) {
        List skyList = userService.lambdaQuery()
                .eq(User::getUserName, "sky")
                .list();
 
        // 因为Page是IPage的实现类，所以可以直接返回page
        // 也可以自己new 一个Page，然后设置值，不过这样就麻烦了
        return page.setRecords(skyList);
    }
 
    @ApiOperation("自定义SQL")
    @GetMapping("customSQL")
    public IPage customSQLPage(Page page) {
        LambdaQueryWrapper wrapper = Wrappers.lambdaQuery();
        wrapper.eq(User::getUserName, "sky");
 
        // 这样写会报错：MybatisPlusException: can not use this method for "getCustomSqlSegment"
        // LambdaQueryChainWrapper wrapper = userService.lambdaQuery()
        //         .eq(User::getUserName, "sky");
 
        return userMapper.findUser(page, wrapper);
    }
}

测试

访问knife4j：http://localhost:8080/doc.html

1. 不传参数

2. 查不存在的数据

3. 手动包装

4. 自定义SQL

以上就是MyBatis-Plus实现分页的方法使用详解的详细内容，更多关于MyBatis-Plus分页的资料请关注脚本之家其它相关文章！

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