springBoot分页查询（使用PageHelper插件）

转载

原文地址：https://www.cnblogs.com/data-magnifier/p/11511404.html

1、配置PageHelper插件依赖

导入maven

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper</artifactId>
    <version>4.1.0</version>
</dependency>

2. 实体类Model

package com.ikeguang.paging.model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import java.io.Serializable;

/**
 * @ Author: keguang
 * @ Date: 2019/6/24 20:18
 * @ version: v1.0.0
 * @ description:
 */
@Entity
public class User implements Serializable{
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue
    private Long id;
    @Column(nullable = false, unique = true)
    private String userName;
    @Column(nullable = false)
    private String passWord;
    @Column(nullable = false, unique = true)
    private String email;
    @Column(nullable = true, unique = true)
    private String nickName;
    @Column(nullable = false)
    private String regTime;

    public User(){}

    public User(String userName, String passWord, String email, String nickName, String regTime) {
        this.userName = userName;
        this.passWord = passWord;
        this.email = email;
        this.nickName = nickName;
        this.regTime = regTime;
    }
    // 省略了必须的getter、setter方法
}

3. Jpa操作数据库

UserRepository.java代码

package com.ikeguang.paging.repository;

import com.ikeguang.paging.model.User;
import org.springframework.data.jpa.repository.JpaRepository;

/**
 * @ Author: keguang
 * @ Date: 2019/7/18 10:23
 * @ version: v1.0.0
 * @ description:
 */
public interface UserRepository extends JpaRepository<User, Long>{

    User findById(long id);

    void deleteById(long id);
}

4. service层

UserService代码

package com.ikeguang.paging.service;

import com.ikeguang.paging.model.User;
import org.springframework.data.domain.Page;

/**
 * @ Author: keguang
 * @ Date: 2019/7/18 10:26
 * @ version: v1.0.0
 * @ description:
 */
public interface UserService {

    Page<User> getUserList(int pageNum, int pageSize);

    User findUserById(long id);

    void save(User user);

    void edit(User user);

    void delete(long id);
}

service实现层

UserServiceImpl.java代码

package com.ikeguang.paging.service.impl;

import com.ikeguang.paging.model.User;
import com.ikeguang.paging.repository.UserRepository;
import com.ikeguang.paging.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;
import org.springframework.stereotype.Service;

/**
 * @ Author: keguang
 * @ Date: 2019/7/18 10:27
 * @ version: v1.0.0
 * @ description:
 */
@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserRepository userRepository;

    @Override
    public Page<User> getUserList(int pageNum, int pageSize) {

        Sort sort = new Sort(Sort.Direction.DESC, "id");
        Pageable pageable = PageRequest.of(pageNum, pageSize, sort);
        Page<User> users = userRepository.findAll(pageable);

        return users;
    }

    @Override
    public User findUserById(long id) {
        return userRepository.findById(id);
    }

    @Override
    public void save(User user) {
        userRepository.save(user);
    }

    @Override
    public void edit(User user) {
        userRepository.save(user);
    }

    @Override
    public void delete(long id) {
        userRepository.deleteById(id);
    }
}

5. Controller层

UserController .java代码

package com.ikeguang.paging.web;

import com.ikeguang.paging.model.User;
import com.ikeguang.paging.service.UserService;
import org.springframework.data.domain.Page;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;

import javax.annotation.Resource;
import java.util.Iterator;

/**
 * @ Author: keguang
 * @ Date: 2019/7/18 10:29
 * @ version: v1.0.0
 * @ description:
 */
@Controller
public class UserController {

    @Resource
    UserService userService;

    @RequestMapping("/")
    public String index() {
        return "redirect:/list";
    }

    @RequestMapping("/list")
    public String list(Model model, @RequestParam(value = "pageNum", defaultValue = "0") int pageNum, @RequestParam(value = "pageSize", defaultValue = "2") int pageSize) {
        System.out.println("============================");
        Page<User> users=userService.getUserList(pageNum, pageSize);
        System.out.println("总页数" + users.getTotalPages());
        System.out.println("当前页是：" + pageNum);

        System.out.println("分页数据：");
        Iterator<User> u = users.iterator();
        while (u.hasNext()){

            System.out.println(u.next().toString());
        }

        model.addAttribute("users", users);


        return "user/list";
    }

    @RequestMapping("/toAdd")
    public String toAdd() {
        return "user/userAdd";
    }

    @RequestMapping("/add")
    public String add(User user) {
        userService.save(user);
        return "redirect:/list";
    }

    @RequestMapping("/toEdit")
    public String toEdit(Model model,Long id) {
        User user=userService.findUserById(id);
        model.addAttribute("user", user);
        return "user/userEdit";
    }

    @RequestMapping("/edit")
    public String edit(User user) {
        userService.edit(user);
        return "redirect:/list";
    }


    @RequestMapping("/delete")
    public String delete(Long id) {
        userService.delete(id);
        return "redirect:/list";
    }
}

application.properties配置文件