手写一个动态分页

近期有个动态分页的需求，所以就尝试了一下手写一个动态分页，这里做个简单的记录。

需求

后台动态分页的实现

项目说明

需要一个已经搭建好的能跑的SSM项目

部分代码

Page.java

package com.yzpt.entity.page;

import java.io.Serializable;
import java.util.List;

import lombok.Getter;
import lombok.Setter;

/**
 * Description: 分页处理的bean
 *
 * @author yzp
 *
 * @date 2019年10月17日
 *
 */
@Setter
@Getter
public class Page<T> implements Serializable{
	/**
	 * serialVersionUID
	 *
	 */
	private static final long serialVersionUID = 1L;
	
	// 必要变量
	private int pageNo;						// 当前页
	private int pageSize = 10;				// 每页的数量 	默认为10 	查询数据时的第二个参数
	private int size;						// 当前页的数量
	private int totalCount;					// 总记录数
	private List<T> resultList;				// list结果
	
	// 页面显示变量
	private int firstData;					// 查询数据时的第一个参数
	private int startPage;					// 首页
	private int endPage;					// 末页
	private int previousPage;				// 上一页
	private int nextPage;					// 下一页
	private int totalPage;					// 总页数
	
	public Page() {
	}
	
	public Page(int firstData, int size, int totalCount, int pageSize, List<T> resultList) {
		this.firstData = firstData;
		this.size = size;
		this.totalCount = totalCount;
		this.pageSize = pageSize;
		this.resultList = resultList;
		
		pageNo = (firstData / pageSize) + 1; 
		totalPage = (totalCount % pageSize) == 0 ? totalCount / pageSize : (totalCount / pageSize) + 1;
		
		if(totalCount == 0 && size == 0 ) {
			pageNo = 1;
			totalPage = 1;
		}
		
		int pageAreaSize = 4;		// 页码显示范围
		startPage = (pageNo - pageAreaSize) < 1 ? 1 : (pageNo - pageAreaSize);
		endPage = (pageNo + pageAreaSize) > totalPage ? totalPage : (pageNo + pageAreaSize);
		previousPage = (pageNo -1) < 1 ? 1 : (pageNo -1);
		nextPage = (pageNo + 1) > totalPage ? totalPage : (pageNo + 1);
	}

	/**  
	 * Description: 获取mysql查询的第一个参数
	 *
	 * @param pageNo
	 * @param pageSize
	 * @return  
	 *
	 */  
	public static int getFirstData(int pageNo, int pageSize) {
		int firstData = (pageNo - 1) * pageSize;
		if(firstData < 1)
			firstData = 0;
		return firstData;
	}	
}

User.java

package com.yzpt.entity.system;

import lombok.Getter;
import lombok.Setter;

/**
 * Description: 用户类
 *
 * @author yzp
 *
 * @date 2019年9月25日
 *
 */
@Setter
@Getter
public class User {
	private Integer id;				// 用户id
	private String userName;		// 用户账号
	private String nickName;		// 用户昵称
	private String password;		// 用户密码
	private String salt;			// 加密密码的盐
	private Integer status;			// 用户状态,0:创建未认证(比如没有激活,没有输入验证码等) --等待验证的用户,1:正常状态,2:用户被锁定 								
	private String age;				// 用户年龄
	private String sex;				// 用户性别
	private String mail;         	// 用户邮箱
	private String photo;			// 用户头像
}

UserController.java

package com.yzpt.web;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.shiro.SecurityUtils;
import org.apache.shiro.authz.annotation.RequiresPermissions;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import com.yzpt.entity.page.Page;
import com.yzpt.entity.system.User;
import com.yzpt.service.UserService;

/**
 * Description: 用户管理控制层
 *
 * @author yzp
 *
 * @date 2019年10月14日
 *
 */
@Controller
@RequestMapping("/user")
public class UserController {
	
	private static final Logger logger = LogManager.getLogger(UserController.class);
	private UserService userService;
	
	@Autowired
	public UserController(UserService userService) {
		this.userService = userService;
	}
	
	/**  
	 * Description: 用户列表查询
	 *
	 * @param request
	 * @param response
	 * @return  
	 *
	 */  
	@RequestMapping(value = "/userList")
	@RequiresPermissions("user:view")
    public String userInfo(HttpServletRequest request, HttpServletResponse response) {
    	String result = "";
    	try {
    		int pageNo = request.getParameter("pageNo") != null ? Integer.valueOf(request.getParameter("pageNo")) : 1;
    		int pageSize = 10;
    		// 查询所有的用户
			Page<User> page = userService.findByPage(pageNo, pageSize);
    		User currentUser = (User)SecurityUtils.getSubject().getPrincipal();
    		request.setAttribute("page", page);
    		request.setAttribute("currentUser", currentUser);
    		result = "userInfoList";
		} catch (Exception e) {
			result = "error";
			logger.info("用户列表查询失败 ----- "+e);
		}
    	return result;
    }

    // 用户添加
	@RequiresPermissions("userInfo:add")
    @RequestMapping("/userAdd")
    public String userInfoAdd(){
        return "userInfoAdd";
    }

    // 用户删除
    @RequestMapping("/userDel")
    @RequiresPermissions("userInfo:del")
    public String userDel(){
        return "userInfoDel";
    }
}

UserServiceImpl.java

package com.yzpt.service.impl;

import java.util.List;

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

import com.yzpt.entity.page.Page;
import com.yzpt.entity.system.User;
import com.yzpt.mapper.UserMapper;
import com.yzpt.service.UserService;

/**
 * Description: 用户业务实现层
 *
 * @author yzp
 *
 * @date 2019年10月14日
 *
 */
@Service
public class UserServiceImpl implements UserService {
	private UserMapper userMapper;

	@Autowired
	public UserServiceImpl(UserMapper userMapper) {
		this.userMapper = userMapper;
	}

	@Override
	public Page<User> findByPage(int pageNo, int pageSize) {
		int totalCount = userMapper.getTotalCount();
		int firstData = Page.getFirstData(pageNo, pageSize);
		List<User> list = userMapper.findByPage(firstData, pageSize);
		int size = list == null ? 0 : list.size();
		return new Page<User>(firstData, size, totalCount, pageSize, list);
	}

}

UserMapper.xml

	 
	
	
	
	
	
	
	
	
	




	select count(*) from t_user 




	select * from t_user order by id asc limit #{firstData}, #{pageSize} 

userInfoList.jsp

<div class="pagination">
	<div class="myPage header">共${page.totalCount }条记录</div>
	<div class="myPage"><a href="user/userList?pageNo=${page.startPage }">首页</a></div>
	<div class="myPage"><a href="user/userList?pageNo=${page.previousPage }">上一页</a></div>
    <c:forEach begin="${page.startPage }" end="${page.endPage }" var="s">
    	<c:choose>
    		<c:when test="${s == page.pageNo }">
    			<div class="active myPage"><a href="user/userList?pageNo=${s }">${s }</a></div>
    		</c:when>
    		<c:otherwise>
    			<div class="myPage"><a href="user/userList?pageNo=${s }">${s }</a></div>
    		</c:otherwise>
    	</c:choose>
    </c:forEach>
    <div class="myPage"><a href="user/userList?pageNo=${page.nextPage }">下一页</a></div>
    <div class="myPage"><a href="user/userList?pageNo=${page.endPage }">末页</a></div>
    <div class="myPage">共${page.totalPage }页</div>
</div>

效果图