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
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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
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<?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
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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）
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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; @Configurationpublic 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
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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
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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; @Repositorypublic 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
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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
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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; @Servicepublic class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService {} |
Controller
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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<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
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分页的资料请关注服务器之家其它相关文章！
原文链接：https://blog.csdn.net/feiying0canglang/article/details/123642286
