通用分页功能实现-优快云博客

通用分页（二）

具体的思路
1、对pagebean增强（添加url、paramMap属性，添加初始化pagebean的方法、最大页、上一页、下一页方法）
2、将按钮条写入标签助手类
3、将隐藏的form表单写入标签助手类
4、将对应的js代码写入标签助手类
5、测试通用分页是否完善

首先写一个实体类:book

package com.lg.entity;

public class Book {
	private int bid;
	private String bname;
	private float price;

	@Override
	public String toString() {
		return "Book [bid=" + bid + ", bname=" + bname + ", price=" + price + "]";
	}

	public int getBid() {
		return bid;
	}

	public void setBid(int bid) {
		this.bid = bid;
	}

	public String getBname() {
		return bname;
	}

	public void setBname(String bname) {
		this.bname = bname;
	}

	public float getPrice() {
		return price;
	}

	public void setPrice(float price) {
		this.price = price;
	}

	public Book(int bid, String bname, float price) {
		super();
		this.bid = bid;
		this.bname = bname;
		this.price = price;
	}

	public Book() {
		super();
	}
	

}

然后我们再写个 PageBean的类代码如下：

package com.lg.util;

import java.util.HashMap;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;

/**
 * 分页工具类
 *
 */
public class PageBean {

	private int page = 1;// 页码

	private int rows = 10;// 页大小

	private int total = 0;// 总记录数
	
//	保留上一次请求的地址
	private String url;
//	保留上一次请求所携带的参数
	private Map<String, String[]> paMap=new HashMap<>();
	
	/**
	 * pageBean初始化方法
	 * @param req
	 */
	public void setRequest(HttpServletRequest req) {
		this.setPage(req.getParameter("page"));
		this.setRows(req.getParameter("rows"));
		this.setPagination(req.getParameter("pagination"));
		
		this.setUrl(req.getRequestURL().toString());
		this.setPaMap(req.getParameterMap());
	}

	public void setPagination(String parameter) {
		if("false".equals(parameter)) {
			this.setPagination(false);
		}
		
	}

	public void setRows(String rows) {
		if(StringUtils.isBlank(rows)) {
			this.setRows(Integer.valueOf(rows));
		}
		
	}

	public void setPage(String page) {
		if(StringUtils.isBlank(page)) {
		this.setPage(Integer.valueOf(page));	
		}
	 
	}

	public String getUrl() {
		return url;
	}

	public void setUrl(String url) {
		this.url = url;
	}

	public Map<String, String[]> getPaMap() {
		return paMap;
	}

	public void setPaMap(Map<String, String[]> paMap) {
		this.paMap = paMap;
	}

	private boolean pagination = true;// 是否分页

	public PageBean() {
		super();
	}

	public int getPage() {
		return page;
	}

	public void setPage(int page) {
		this.page = page;
	}

	public int getRows() {
		return rows;
	}

	public void setRows(int rows) {
		this.rows = rows;
	}

	public int getTotal() {
		return total;
	}

	public void setTotal(int total) {
		this.total = total;
	}

	public void setTotal(String total) {
		this.total = Integer.parseInt(total);
	}

	public boolean isPagination() {
		return pagination;
	}

	public void setPagination(boolean pagination) {
		this.pagination = pagination;
	}

	/**
	 * 获得起始记录的下标
	 * 
	 * @return
	 */
	public int getStartIndex() {
		return (this.page - 1) * this.rows;
	}

	@Override
	public String toString() {
		return "PageBean [page=" + page + ", rows=" + rows + ", total=" + total + ", pagination=" + pagination + "]";
	}
	
	/**
	 * 最大页码
	 * @return
	 */
public int getMaxPage() {
		
		return this.total % this.rows ==0 ? this.total/this.rows : this.total/this.rows +1;	
	}
	
	/**
	 * 获取下一页
	 * @return
	 */
	public int getNextPage() {
		return 	this.page < this.getMaxPage() ? this.page+1 : this.page;
	}
	
	/**
	 * 获取上一页
	 * @return
	 */
	
public int getPreviousPage() {
		return this.page >1 ? this.page : this.page;
	}

}

再写一个Servlet类代码如下：

package com.lg.web;

import java.io.IOException;
import java.util.List;
import java.util.Map;

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

import com.lg.dao.BookDao;
import com.lg.entity.Book;
import com.lg.util.PageBean;

public class BookServlet extends HttpServlet {

	private static final long serialVersionUID = -125095976312901601L;
	private BookDao bookDao=new BookDao();
	
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		doPost(req, resp);
	}
	
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		String bname = req.getParameter("bname");
		Book book = new Book();
		book.setBname(bname);
		PageBean pageBean=new PageBean();
		Map<String, String[]> parameterMap =req.getParameterMap();
		String url=req.getRequestURL().toString();
		try {
		  List<Book> list = bookDao.list(book, pageBean);
			req.setAttribute("bookList", list);
			req.getRequestDispatcher("/bookList.jsp").forward(req, resp);
		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		}
	}

}

实现自定义分页标签

写一个助手类PageTag 代码如下：

package com.lg.tags;

import java.io.IOException;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyTagSupport;

import com.wangshaoyang.util.PageBean;


public class PageTag extends BodyTagSupport {
	private static final long serialVersionUID = -4075330492140277510L;
	private PageBean pageBean;

	@Override
	public int doStartTag() throws JspException {
		JspWriter out = pageContext.getOut();
		try {
			out.write(toHTML());
		} catch (IOException e) {
			e.printStackTrace();
		}
		return super.doStartTag();
	}

	public String toHTML() {
		StringBuffer sb = new StringBuffer();
		
		// 下一次请求提交到后台的表单html代码拼接
		sb.append("<form id='pageBeanForm' action='" + pageBean.getUrl() + "' method='post'>");
		Map<String, String[]> paramMap = pageBean.getParamMap();
		if (paramMap != null && paramMap.size() > 0) {
			for (Entry<String, String[]> entry : paramMap.entrySet()) {
				if (!"page".equals(entry.getKey())) {
					for(String val : entry.getValue()) {
						sb.append("<input type='hidden' name='" + entry.getKey() + "' value='" + val + "' >");
					}
				}
			}
		}
		sb.append("<input type='hidden' name='page'>");
		sb.append("</form>");

		// 分页条html代码拼接
		sb.append("<div style='text-align: right; font-size: 12px;'>");
		sb.append("	每页"+pageBean.getRows()+"条，共"+pageBean.getTotal()+"条，第"+pageBean.getPage()+"页，共"+pageBean.getMaxPage()+"页&nbsp;&nbsp;<a ");
		sb.append("	href='javascript:gotoPage(1)'>首页</a>&nbsp;&nbsp;<a");
		sb.append("	href='javascript:gotoPage("+pageBean.getPreviousPage()+")'>上一页</a>&nbsp;&nbsp;<a");

		sb.append("	href='javascript:gotoPage("+pageBean.getNextPage()+")'>下一页</a>&nbsp;&nbsp;<a");
		sb.append("	href='javascript:gotoPage("+pageBean.getMaxPage()+")'>尾页</a>&nbsp;&nbsp;<input type='text'");
		sb.append("	id='skipPage'");
		sb.append("	style='text-align: center; font-size: 12px; width: 50px;'>&nbsp;&nbsp;<a");
		sb.append("	href='javascript:skipPage()'>Go</a>");
		sb.append("</div>");
		// 分页所需要调用的js代码
		sb.append("<script type='text/javascript'>");
		sb.append("	function gotoPage(page) {");
		sb.append("		document.getElementById('pageBeanForm').page.value = page;");
		sb.append("		document.getElementById('pageBeanForm').submit();");
		sb.append("	}");
		sb.append("	function skipPage() {");
		sb.append("		var page = document.getElementById('skipPage').value;");
		sb.append("		if(!page || isNaN(page) || parseInt(page)<1 || parseInt(page)>"+pageBean.getMaxPage()+"){");
		sb.append("			alert('请输入1~N的数字');");
		sb.append("			return;");
		sb.append("		}");
		sb.append("		gotoPage(page);");
		sb.append("	}");
		sb.append("</script>");
		return sb.toString();
	}
	public PageBean getPageBean() {
		return pageBean;
	}
	public void setPageBean(PageBean pageBean) {
		this.pageBean = pageBean;
	}
}

写一个jsp界面来进行测试

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
    <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
    <%@ taglib uri="/guang"  prefix=”z" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h2>小说目录</h2>
	<br>

	<form action="${pageContext.request.contextPath}/bookServlet"
		method="post">
<!-- 		<input type="hidden" name="rows" value="20"> -->
		<input type="hidden" name="pagination" value="false">
		书名：<input type="text" name="bname"> <input type="submit"
			value="确定">
	</form>
	<table border="1" width="100%">
		<tr>
			<td>编号</td>
			<td>名称</td>
			<td>价格</td>
		</tr>
		<c:forEach items="${bookList }" var="b">
			<tr>
				<td>${b.bid }</td>
				<td>${b.bname }</td>
				<td>${b.price }</td>
			</tr>
		</c:forEach>
	</table>
	
	<z:page pageBean="${pagebean }"></w:page>
	
</body>
</html>