pageHelper
PageHelper 是一款好用的开源免费的 Mybatis 第三方物理分页插件
物理分页
支持常见的 12 种数据库。Oracle,MySql,MariaDB,SQLite,DB2,PostgreSQL,SqlServer 等
支持多种分页方式
支持常见的 RowBounds(PageRowBounds)，PageHelper.startPage 方法调用，Mapper 接口参数调用
pageHelper底层会帮助生成一下分页语句 limit相关
废话不多说，赶紧动手！
pom文件：
<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 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>pageHelper</groupId> <artifactId>com.toov5.pageHelper</artifactId> <version>0.0.1-SNAPSHOT</version> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.0.0.RELEASE</version> </parent> <dependencies> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <!-- 测试 --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>1.1.1</version> </dependency> <!-- mysql 依赖 --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency> <!-- springboot-web组件 --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <!-- springboot 整合 pagehelper --> <dependency> <groupId>com.github.pagehelper</groupId> <artifactId>pagehelper-spring-boot-starter</artifactId> <version>1.2.5</version> </dependency> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-lang3</artifactId> <version>3.7</version> </dependency> </dependencies> </project>
application.properties
spring.datasource.url=jdbc:mysql://localhost:3306/test spring.datasource.username=root spring.datasource.password=root spring.datasource.driver-class-name=com.mysql.jdbc.Driver logging.level.com.example.demo.dao=DEBUG pagehelper.helperDialect=mysql pagehelper.reasonable=true pagehelper.supportMethodsArguments=true pagehelper.params=count=countSql pagehelper.page-size-zero=true
entity:
package com.toov5.entity; import lombok.Data; @Data public class User { private Integer id; private String name; private Integer age; }
mapper:
package com.toov5.mapper; import java.util.List; import org.apache.ibatis.annotations.Select; import com.toov5.entity.User; public interface UserMapper { @Select("SELECT * FROM USERS ") List<User> findUserList(); }
service
package com.toov5.service; import java.util.List; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import com.github.pagehelper.PageHelper; import com.github.pagehelper.PageInfo; import com.toov5.entity.User; import com.toov5.mapper.UserMapper; @Service public class UserService { @Autowired private UserMapper userMapper; //当前页 一页多少个 mysql通过limit分页的哈 public PageInfo<User> findUserList(int page, int size) { // 开启分页插件,放在查询语句上面 帮助生成分页语句 PageHelper.startPage(page, size); //底层实现原理采用改写语句 将下面的方法中的sql语句获取到然后做个拼接 limit AOPjishu List<User> listUser = userMapper.findUserList(); // 封装分页之后的数据 返回给客户端展示 PageInfo做了一些封装 作为一个类 PageInfo<User> pageInfoUser = new PageInfo<User>(listUser); return pageInfoUser; } }
controller
package com.toov5.controller; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; import com.github.pagehelper.PageInfo; import com.toov5.entity.User; import com.toov5.service.UserService; @RestController public class IndexController { @Autowired private UserService userService; @RequestMapping("/findUserList") public PageInfo<User> findUserList(int page, int size) { System.out.println("#############################"); return userService.findUserList(page, size); } }
启动类
package com.toov5; import org.mybatis.spring.annotation.MapperScan; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; @MapperScan("com.toov5.*") @SpringBootApplication public class PageHelper { public static void main(String[] args) { SpringApplication.run(PageHelper.class, args); } }
项目启动：
访问
json解析：
{
"total": 4,
"list": [{
"id": 1,
"name": "toov5",
"age": 12
}, {
"id": 2,
"name": "cc",
"age": 99
}],
"pageNum": 1,
"pageSize": 2,
"size": 2,
"startRow": 1,
"endRow": 2,
"pages": 2,
"prePage": 0,
"nextPage": 2,
"isFirstPage": true,
"isLastPage": false,
"hasPreviousPage": false,
"hasNextPage": true,
"navigatePages": 8,
"navigatepageNums": [1, 2],
"navigateFirstPage": 1,
"navigateLastPage": 2,
"firstPage": 1,
"lastPage": 2
}
小伙伴们是不是返回的信息量十足呀~
PS：如果每个查询方面前面都这样：
如果每个方法查询之前 之后 都加这么个方法的话 很冗余啊
冗余 则 aop封装
模板设计方法模式！！！哈哈哈 有兴趣的可以玩玩
原创文章，作者：奋斗，如若转载，请注明出处：https://blog.ytso.com/tech/pnotes/16153.html