MyBatis-Plus实现分页的⽅法使⽤详解⽬录
简介
建库建表
依赖
配置
代码
Entity
Mapper
Service
Controller
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', '2021-01-23 09:33:36', '2021-01-23 09:33:36', 0);
INSERT INTO `t_user` VALUES (2, 'sky', '天蓝', '123@qq', '2021-01-24 18:12:21', '2021-01-24 18:12:21', 0);
依赖
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="/POM/4.0.0" xmlns:xsi="/2001/XMLSchema-instance"
xsi:schemaLocation="/POM/4.0.0 /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&le</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
spring:
datasource:
driver-class-name: sql.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）
fig;
import batisplus.annotation.DbType;
import sion.plugins.MybatisPlusInterceptor;
import t.annotation.Bean;
import t.annotation.Configuration;
import sion.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
ample.ity;
import batisplus.annotation.IdType;
import batisplus.annotation.TableId;
import batisplus.annotation.TableLogic;
import batisplus.annotation.TableName;
import sion.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
ample.demo.user.mapper;
import ditions.Wrapper;
import apper.BaseMapper;
import adata.IPage;
import lkit.Constants;
ample.ity.User;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
import org.springframework.stereotype.Repository;
@Repository
public interface UserMapper extends BaseMapper<User> {
@Select("SELECT * FROM t_user ${ew.customSqlSegment}")
IPage<User> findUser(IPage<User> page, @Param(Constants.WRAPPER) Wrapper wrapper); }
Service
接⼝
ample.demo.user.service;
import sion.service.IService;
ample.ity.User;
public interface UserService extends IService<User> {
}
实现
ample.demo.user.service.impl;
import sion.service.impl.ServiceImpl;
ample.ity.User;
ample.demo.user.mapper.UserMapper;
ample.demo.user.service.UserService;
import org.springframework.stereotype.Service;
@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService { }
Controller
ample.ller;
import ditions.query.LambdaQueryWrapper;
import adata.IPage;
import lkit.Wrappers;
import ditions.query.LambdaQueryChainWrapper;
import sion.plugins.pagination.Page;
ample.ity.User;
ample.demo.user.mapper.UserMapper;
ample.demo.user.service.UserService;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import org.springframework.beans.factory.annotation.Autowired;
mybatis和springmvcimport 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<User> noParam(Page<User> page) {
return userService.page(page);
}
@ApiOperation("查不存在的数据")
@GetMapping("notExist")
public IPage<User> notExist(Page<User> 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<User> manualPack(Page<User> page) {
List<User> 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<User> customSQLPage(Page<User> page) {
LambdaQueryWrapper<User> wrapper = Wrappers.lambdaQuery();
wrapper.eq(User::getUserName, "sky");
// 这样写会报错：MybatisPlusException: can not use this method for "getCustomSqlSegment" // LambdaQueryChainWrapper<User> wrapper = userService.lambdaQuery()
// .eq(User::getUserName, "sky");
return userMapper.findUser(page, wrapper);
}
}
测试
1. 不传参数
2. 查不存在的数据
3. ⼿动包装
4. ⾃定义SQL
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