[大数据]JavaWeb实现分页哦

JavaWeb实现分页哦

分页是现在项目必备的功能，那我们来看看哦

1.首先分析分页需要哪些数据？？？

1.总记录数totalpageCount
   sql语句 select count(*)from 表名
2.每页显示的数量 pageSize
                 1.客户端进行传递
				 2.由页面进行传递
3.总页数  totalPage
   总记录数/每页显示的数量
   注意：如果总记录数/每页的数量>0,则总页码+1
4.当前页currentPage
  客户端进行传递的
5.每页的数据 <List>
   通过sql语句求得：
   select * from 表名 limit begin pageSize
   begin可以由公式求得：(currentPage-1)*pageSizes

2.知道了数据之后，我们来写业务逻辑

业务逻辑：
1.编写page类
2.点击当前页的时候，需要传递两个参数：currentPage和pageSize
   servlet页面：1.接受参数
                2.调用service查询page
				   1.创建空的page对象
				   2.设置当前页面属性curentPage和每页显示的数量pageSize
				   3.调用dao查询总记录数pageTotalCount
				   4.调用dao查询list集合
				     （int begin，int pageSize）
				   5.计算总页码
				     总记录数/每页显示的数量
					 totalPage/pageSize
					 
					(dao层)
					1.查询总记录数的方法 
					2.查询每页显示的数据的方法(int begin,int pageSize)
				3.将page存入request
				4.转发list.jsp显示

3.直接上代码

实体Page类

package com.cn.pojo;

import java.util.List;

public class Page<T> {

	// 当前页
	private int currentPage;
	// 每一页的数量
	private int pageSize;
	// 总记录数
	private int totalPageCount;
	// 总页数
	private int totalPage;
	// 每一页的数据------泛型
	private List<T> list;

	public Page() {
		super();
	}

	public Page(int currentPage, int pageSize, int totalPageCount, int totalPage, List<T> list) {
		super();
		this.currentPage = currentPage;
		this.pageSize = pageSize;
		this.totalPageCount = totalPageCount;
		this.totalPage = totalPage;
		this.list = list;
	}

	public int getCurrentPage() {
		return currentPage;
	}

	public void setCurrentPage(int currentPage) {
		this.currentPage = currentPage;
	}

	public int getPageSize() {
		return pageSize;
	}

	public void setPageSize(int pageSize) {
		this.pageSize = pageSize;
	}

	public int getTotalPageCount() {
		return totalPageCount;
	}

	public void setTotalPageCount(int totalPageCount) {
		this.totalPageCount = totalPageCount;
	}

	public int getTotalPage() {
		return totalPage;
	}

	public void setTotalPage(int totalPage) {
		this.totalPage = totalPage;
	}

	public List<T> getList() {
		return list;
	}

	public void setList(List<T> list) {
		this.list = list;
	}
}

servlet页面 BookPageServlet

package com.cn.servlet;

import java.io.IOException;
import java.sql.SQLException;
import java.util.List;

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

import org.omg.CosNaming.NamingContextExtPackage.StringNameHelper;

import com.cn.pojo.Book;
import com.cn.pojo.Page;
import com.cn.service.BookService;

/**
 * Servlet implementation class BookPageServlet
 */
public class BookPageServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public BookPageServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	 
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		request.setCharacterEncoding("UTF-8");
		//获得前端的值
		String currentPage = request.getParameter("currentPage");
		String pageSize = request.getParameter("pageSize");
		
		//防止空指针异常
		if(currentPage == null || "".equals(currentPage)) {
			currentPage="1";
		}
		if(pageSize == null || "".equals(pageSize)) {
			pageSize="5";
		}
		
		//存到request里
		try {
			Page<Book> page = BookService.findPage(currentPage, pageSize);
			request.setAttribute("page", page);
			//转发你想要的页面
			request.getRequestDispatcher("bookall.jsp").forward(request, response);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

BookService层

public static Page<Book> findPage(String _currentPage,String _pageSize) throws SQLException{
		//1.转化类型
		int currentPage = Integer.valueOf(_currentPage);
		int pageSize = Integer.valueOf(_pageSize);
		//2.new对象
		Page<Book> page = new Page<>();
		//3.赋值当前页 每一页的数量
		page.setCurrentPage(currentPage);
		page.setPageSize(pageSize);
		
		//4.计算总记录数
		int totalPageCount = JDBCDemo.totalPageCount();
		page.setTotalPageCount(totalPageCount);
		
		//5.计算总页数
		int totalPage = totalPageCount % pageSize == 0 ?(totalPageCount/pageSize):(totalPageCount/pageSize+1);
		page.setTotalPage(totalPage);
		
		//6.每一页的数据
		int begin = (currentPage-1)*pageSize+1;
		List<Book> list = JDBCDemo.page(begin, pageSize);
		page.setList(list);
		return page;
		
	}

我直接写的JDBC，没有实现接口哦~

//计算总记录数
	public static int totalPageCount() throws SQLException {
		String sql = "select count(*) from book_table";
		PreparedStatement statement = connection.prepareStatement(sql);
		ResultSet set = statement.executeQuery();
		int totalPageCount = 0;
		//判断是否有内容
		while(set.next()) {
		//获取当前的内容
			totalPageCount = set.getInt(1);
		}
		return totalPageCount;
	}
	
	
	//每一页的数据
	public static List<Book> page(int begin,int pageSize) throws SQLException {
		String sql = "select * from book_table limit ?,?";
		PreparedStatement statement = connection.prepareStatement(sql);
		statement.setInt(1, begin);
		statement.setInt(2, pageSize);
		List<Book> list = new ArrayList<Book>();
		ResultSet set = statement.executeQuery();
		Book book = null;
		while (set.next()) {
			book = new Book();
			book.setBookNum(set.getInt("book_num"));
			book.setBookName(set.getString("book_name"));
			book.setBookAuthor(set.getString("book_author"));
			book.setBookPrice(set.getInt("book_price"));
			book.setBookPress(set.getString("book_press"));
			book.setBookIntroduction(set.getString("book_introduction"));
			list.add(book);
		}
		return list;
	}
	

因为我转发到bookall.jsp页面，这里是我的bookall.jsp页面

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<%@taglib  uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<title>Insert title here</title>
</head>
<body>
	<table border="3">
		<tr>
		
			<th>图书编号</th>
			<th>图书名字</th>
			<th>图书作者</th>
			<th>图书价格</th>
			<th>图书出版社</th>
			<th>图书介绍</th>
			<th>操作</th>
		</tr>
		//page存到request里了
		<c:forEach items="${page.list}" var = "book" >
		<tr>
	
		<td>${book.bookNum}</td>
		<td>${book.bookName}</td>
		<td>${book.bookAuthor}</td>
		<td>${book.bookPrice}</td>
		<td>${book.bookPress}</td>
		<td>${book.bookIntroduction}</td>
		<td>
		<a href = "InforServlet?bookNum=${book.bookNum}">修改</a>
		<a href = "DeleteeServlet?bookNum=${book.bookNum}">删除</a>
		</td>
		</tr>
		</c:forEach>	
	</table>
	//上一页  =  当前页-1
	<c:if test="${page.currentPage != 1}">
	<a style="color:red" href="BookPageServlet?currentPage=${page.currentPage-1}&pageSize=5">上一页</a>
	</c:if>
	
	//循环输出每一页
	<c:forEach begin="1" end="${page.totalPage}" var="i"> 
	<c:if test="${page.currentPage == i}">
	//如果点击当前页，就让页码变红色，其余的不变颜色
	//href要把地址带过来，否则你的数据不会更新
	<a style="color:red" href="BookPageServlet?currentPage=${i}&pageSize=5">${i}</a>
	</c:if>
	
	//下一页 = 当前页+1 
	<c:if test="${page.currentPage != i}">
	<a href="BookPageServlet?currentPage=${i}&pageSize=5">${i}</a>
	</c:if>
	</c:forEach>
	<c:if test="${page.currentPage != page.totalPage}">
	<a style="color:red" href="BookPageServlet?currentPage=${page.currentPage+1}&pageSize=5">下一页</a>
	</c:if>
	
	总共${page.totalPageCount}条数据,总共${page.totalPage}页
	
	
</body>
</html>

下图就是服务启动之后的页面展示...

以上就是javaWeb的分页哦，希望可以对大家有所帮助啦