springboot中使用mybatis的分页插件pageHelper

时间：2023-03-09 13:11:48
springboot中使用mybatis的分页插件pageHelper

首先在pom.xml中配置

<!-- https://mvnrepository.com/artifact/org.mybatis.spring.boot/mybatis-spring-boot-starter -->

<dependency>

    <groupId>org.mybatis.spring.boot</groupId>

    <artifactId>mybatis-spring-boot-starter</artifactId>

    <version>2.1.0</version>

</dependency>

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->

<dependency>

    <groupId>mysql</groupId>

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

    <version>8.0.16</version>

</dependency>
<!-- https://mvnrepository.com/artifact/com.github.pagehelper/pagehelper-spring-boot-starter -->
<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.2.12</version>
</dependency>

然后就是写代码了，最重要的两个类是：

import com.github.pagehelper.PageHelper;

import com.github.pagehelper.PageInfo;
import com.alibaba.fastjson.JSON;

import com.github.pagehelper.PageHelper;

import com.github.pagehelper.PageInfo;

import com.yuanqiao.dao.UserDao;

import com.yuanqiao.entity.User;

import com.yuanqiao.service.UserService;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Service;

import java.util.List;

@Service

public class UserServiceImpl implements UserService {

    @Autowired

    private UserDao userDao;

    @Override

    public PageInfo<User> getAllUsers(int pageNum,int pageSize) {

        PageHelper.startPage(pageNum,pageSize);

        List<User> allUsers = userDao.getAllUsers();

        PageInfo<User> pageInfo=new PageInfo<>(allUsers);

        return pageInfo;

    }

    @Override

    public User getUserById(Integer id) {

        User user = userDao.getUserById(id);

        System.out.println("------------------这里打印了吗?------------------------------");

        System.out.println(JSON.toJSONString(user));

        return user;

    }

}

执行测试类

package com.yuanqiao.service;

import org.junit.Test;

import org.junit.runner.RunWith;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.boot.test.context.SpringBootTest;

import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)

@SpringBootTest

public class UserServiceTest {

    @Autowired

    private UserService userService;

    @Test

    public void getAllUsers(){

        userService.getAllUsers(1,2);

    }

    @Test

    public void getAllUsers002(){

        userService.getAllUsers(2,3);

    }

}

数据库数据如下；

springboot中使用mybatis的分页插件pageHelper

测试sql日志结果如下：

2019-08-03 00:21:00.053  INFO 24268 --- [           main] com.alibaba.druid.pool.DruidDataSource   : {dataSource-1} inited

JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@6d963d70] will not be managed by Spring

==>  Preparing: SELECT count(0) FROM user

==> Parameters:

<==    Columns: count(0)

<==        Row: 14

<==      Total: 1

==>  Preparing: select * from user LIMIT ?, ?

==> Parameters: 3(Integer), 3(Integer)

<==    Columns: id, name, sex, age

<==        Row: 4, zhangsan, female, 33

<==        Row: 5, zhangsan, male, 18

<==        Row: 6, zhangsan, male, 19

<==      Total: 3

可以看到pageHelper实质是帮我们重新封装了sql的，并没有全表扫描出来再物理组装，所以是很高级的一个工具了。

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