通用分页（二）

于 2019-07-22 02:25:22 发布
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文章标签： 通用分页（二）
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本文链接：https://blog.youkuaiyun.com/JAVAwangjing/article/details/96794463

通用分页（二）

通用分页：将上一次查询请求再发一次，只不过改变了页码。
具体思路：
1、补全servlet
2、页面展示
3、分页重要参数（page、rows、是否分页、上一次请求、上一次的表单参数）
4、自定义分页标签

PageBean类：
主要是为了分页

package com.wangjing.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
	
//	保留上一次的请求地址
	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.isNotBlank(rows)) {
			this.setRows(Integer.valueOf(rows));
		}
	}

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

	private boolean pagination = true;// 是否分页

	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;
	}

	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;
		
	}
	
	/**
	 * 下一页
	 * @return
	 */
	public int getNextPage() {
		return this.page < this.getMaxPage() ? this.page + 1 : this.page;
	}
	
	/**
	 * 上一页
	 * @return
	 */
	public int getPreviouPage() {
		return this.page > 1 ? this.page-1 : this.page;
		
	}
	
}

pageTag类：
解决代码的重复利用

package com.wangjing.tag;

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.wangjing.util.PageBean;

public class PageTag extends BodyTagSupport {

	private static final long serialVersionUID = -6356274451220112552L;
	
	private PageBean pageBean;

	public PageBean getPageBean() {
		return pageBean;
	}

	public void setPageBean(PageBean pageBean) {
		this.pageBean = pageBean;
	}
	@Override
	public int doStartTag() throws JspException {
		JspWriter out = pageContext.getOut();
		try {
			out.print(toHTML());
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return SKIP_BODY;
	}

	private String toHTML() {
		StringBuilder sb=new StringBuilder();
		
//		拼接下一次分页请求所提交的分页表单
		sb.append("<form id='pageBeanForm' action='"+pageBean.getUrl()+"' method='post'>");
		sb.append("<input type='hidden' name='page'>");
		Map<String, String []> paMap = pageBean.getPaMap();
		if(paMap != null && paMap.size()>0) {
			Set<Entry<String, String[]>> entrySet = paMap.entrySet();
			for (Entry<String, String[]> entry : entrySet) {
				for(String value : entry.getValue()){
					sb.append("<input type='hidden' name='"+entry.getKey()+"' value='"+value+"'>");
				}
			}
		}
		sb.append("</form>");
		
//		拼接分页条
		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.getPreviouPage()+")'>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>");
//		拼接分页JavaScript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();
	}
}

wangjing.tld类：
自定义标签

<?xml version="1.0" encoding="UTF-8" ?>

<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
    version="2.0">
    
  <description>wj 1.1 core library</description>
  <display-name>wj core</display-name>
  <tlib-version>1.1</tlib-version>
  <short-name>c</short-name>
  <uri>/wangjing</uri>

  <tag>
  <!-- 填写的是标签中的标签名 -->
    <name>page</name>
    <!-- 标签对应的后台助手类 -->
    <tag-class>com.wangjing.tag.PageTag</tag-class>
     <!-- 标签类别 -->
    <body-content>JSP</body-content>
    <attribute>
     <!-- 自定义标签中的属性  -->
        <name>pageBean</name>
        <!-- 属性值是否必填 -->
        <required>true</required>
        <!-- 是否支持表达式EL表达式 -->
        <rtexprvalue>true</rtexprvalue>
    </attribute>
  </tag>
</taglib>

BookServlet类：

package com.wangjing.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.wangjing.dao.BookDao;
import com.wangjing.entity.Book;
import com.wangjing.util.PageBean;

public class BookServlet extends HttpServlet {

	private static final long serialVersionUID = -4640947398076182188L;
	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) {
			e.printStackTrace();
		}
	}
}

web.xml：
配置servlet

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>pagebean</display-name>
  <filter>
 	 <filter-name>encodingFiter</filter-name>
  	<filter-class>com.wangjing.util.EncodingFiter</filter-class>
  </filter>
  <filter-mapping>
  	<filter-name>encodingFiter</filter-name>
  	<url-pattern>/*</url-pattern>
  </filter-mapping>
  
 <servlet>
  	<servlet-name>bookServlet</servlet-name>
  	<servlet-class>com.wangjing.web.BookServlet</servlet-class>
  </servlet>
  <servlet-mapping>
  	<servlet-name>bookServlet</servlet-name>
  	<url-pattern>/bookServlet</url-pattern>
  </servlet-mapping>
</web-app>

bookList包：
主要为了显示

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@taglib prefix="w" uri="/wangjing" %>
<!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="${pageContext.request.contextPath}/bookServlet"
		method="post">
		书名：<input type="text" name="bname"> <input type="submit"
			value="确定">
	</form>
	<table border="1" width="100%">
		<tr>
			<td>编号</td>
			<td>名称</td>
			<td>价格</td>
		</tr>
		<c:forEach items="${bookList}" var="b">
			<tr>
				<td>${b.bid }</td>
				<td>${b.bname }</td>
				<td>${b.price }</td>
			</tr>
		</c:forEach>
	</table>
	<w:page pageBean="${pageBean}"></w:page>
	
</body>
</html>

浏览器显示图片：
在这里插入图片描述

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