ssh自定义分页标签

一、标签处理类：
/**
 *  ClassName: PagerTag.java
 *  created on Oct 21, 2008
 *  Copyrights 2008 qjyong All rights reserved.
 *  EMail: qjyong@gmail.com
 */
package com.qiujy.tags;
import java.io.IOException;
import java.util.Enumeration;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
/**
 * 自定义分页标签 
 * 使用方式 <my:pager pageSize="10" 
 *                   pageNo="1" 
 *                   recordCount="100"
 *                   url="index.jsp" />
 * 
 * @author qiujy
 * 
 */
public class PagerTag extends TagSupport {
    private int pageSize = 10; // 每页要显示的记录数
    private int pageNo = 1; // 页号
    private int recordCount; // 总记录数
    private String url; // 目的地URL
    
    public void setPageSize(int pageSize) {
        this.pageSize = pageSize;
    }
    public void setPageNo(int pageNo) {
        this.pageNo = pageNo;
    }
    public void setRecordCount(int recordCount) {
        this.recordCount = recordCount;
    }
    public void setUrl(String url) {
        this.url = url;
    }
    // 主要的逻辑
    @Override
    public int doStartTag() throws JspException {
        if(recordCount == 0){
            return super.doStartTag();
        }
        
        // 总页数
        int pageCount = (recordCount + pageSize - 1) / pageSize;
        // 页号越界处理
        if (pageNo > pageCount) {
            pageNo = pageCount;
        }
        if (pageNo < 1) {
            pageNo = 1;
        }
        
        StringBuilder sb = new StringBuilder();
        
        sb.append("<form name='pageController' id='pageController' action='' method='post'>/r/n")
          .append("<input type='hidden' id='pageNo' name='pageNo' value='" + pageNo + "' />/r/n");
        
        //------------------------------------ 获取所有請求中的参数
        HttpServletRequest request = (HttpServletRequest) pageContext
                .getRequest();
        Enumeration<String> enumeration = request.getParameterNames();
        String name = null;
        String value = null;
        //把请求中的所有参数当作隐藏表单域在页面中写出)
        while (enumeration.hasMoreElements()) {
            name =  enumeration.nextElement();
            value = request.getParameter(name);
            // 去除页号
            if (name.equals("pageNo")) {
                if (null != value && !"".equals(value)) {
                    pageNo = Integer.parseInt(value);
                }
                continue;
            }
            sb.append("<input type='hidden' name='")
              .append(name)
              .append("' value='")
              .append(value)
              .append("'/>/r/n");
        }
        //----------------------------------------------------
        
          
        sb.append(" 总共有" + pageCount + "页,")
          .append("当前是第" + pageNo + "页 /r/n");
        
        if (pageNo == 1) {
            sb.append("首页");
            sb.append(" ");
            sb.append("上一页/r/n");
        } else {
            sb.append("<a href='#' onclick='turnOverPage(1)'>首页</a>/r/n");
            sb.append(" ");
            sb.append("<a href='#' onclick='turnOverPage(")
                    .append((pageNo - 1)).append(")'>上一页</a>/r/n");
        }
        sb.append(" ");
        if (pageNo == pageCount) {
            sb.append("下一页");
            sb.append(" ");
            sb.append("尾页/r/n");
        } else {
            sb.append("<a href='#' onclick='turnOverPage(")
                    .append((pageNo + 1)).append(")'>下一页</a>/r/n");
            sb.append(" ");
            sb.append("<a href='#' onclick='turnOverPage(").append(pageCount)
                    .append(")'>尾页</a>/r/n");
        }
        
        sb.append(" 跳到<select onChange='turnOverPage(this.value)'>/r/n");
        for (int i = 1; i <= pageCount; i++) {
            if (i == pageNo) {
                sb.append("  <option value='")
                  .append(i)
                  .append("' selected='selected'>第")
                  .append(i)
                  .append("页</option>/r/n");
            } else {
                sb.append("  <option value='")
                  .append(i)
                  .append("'>第")
                  .append(i)
                  .append("页</option>/r/n");
            }
        }
        sb.append("</select>/r/n");
        sb.append(" /r/n");
        sb.append("</form>/r/n");
        
        // 生成提交表单的JS
        sb.append("<script language='javascript'>/r/n");
        sb.append("  //翻页函数/t/n");
        sb.append("  function turnOverPage(no){/r/n");
        sb.append("    var form = document.pageController;/r/n");
        sb.append("    //页号越界处理/r/n");
        sb.append("    if(no").append(">").append(pageCount).append(") {/r/n");
        sb.append("        no=").append(pageCount).append(";/r/n");
        sb.append("    }/r/n");
        sb.append("    if(no").append("< 1){/r/n");
        sb.append("        no=1;/r/n");
        sb.append("    }/r/n");
        sb.append("    form.").append("pageNo").append(".value=no;/r/n");
        sb.append("    form.action='").append(url).append("';/r/n");
        sb.append("    form.submit();/r/n");
        sb.append("  }/r/n");
        sb.append("</script>/r/n");
        
        try {
            pageContext.getOut().println(sb.toString());
        } catch (IOException e) {
            e.printStackTrace();
        }
        
        return super.doStartTag();
    }
}
二、标签库描述文件：
<?xml version="1.0" encoding="UTF-8"?>
<taglib version="2.0" 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 web-jsptaglibrary_2_0.xsd">
 <tlib-version>2.0</tlib-version>
 <short-name>my</short-name>
 <uri>http://blog.csdn.net/qjyong</uri>
 <tag>
    <description>通用分页标签</description>
    <name>pager</name>
    <tag-class>com.qiujy.tags.PagerTag</tag-class>
    <body-content>empty</body-content>
    <attribute>
      <name>pageNo</name>
      <required>true</required>
      <rtexprvalue>true</rtexprvalue> 
    </attribute>
    <attribute>
      <name>recordCount</name>
      <required>true</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>pageSize</name>
      <required>true</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>url</name>
      <required>true</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
  </tag>
</taglib>
三、把标签处理类和tld打成pager.jar包。使用时只需添加到项目的类路径中即可。
 
四、测试：先写一个Servlet来创建测试数据
package com.qiujy.web.servlet;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class MyServlet extends HttpServlet {
    
    public static List<String> list = new ArrayList<String>();
    
    public MyServlet(){
        for(int i = 0; i < 100; i++){
            list.add("aaa" + i);
        }
    }
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        this.doPost(request, response);
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String pageNoStr = request.getParameter("pageNo");
        int pageNo = 1;
        if(pageNoStr != null && !pageNoStr.equals("")){
            pageNo = Integer.parseInt(pageNoStr);
        }
        
        int recordCount = list.size();
        int pageSize = 10;
        int startNo = (pageNo - 1) * pageSize;
        
        List<String> result = list.subList(startNo, startNo + 10);
        
        request.setAttribute("recordCount", recordCount);
        request.setAttribute("pageNo", pageNo);
        request.setAttribute("pageSize", pageSize);
        request.setAttribute("data", result);
        
        request.getRequestDispatcher("index.jsp").forward(request, response);
    }
}
web.xml：
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" 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-app_2_4.xsd">
    <servlet>
        <servlet-name>pageTestServlet</servlet-name>
        <servlet-class>com.qiujy.web.servlet.MyServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>pageTestServlet</servlet-name>
        <url-pattern>/testpager</url-pattern>
    </servlet-mapping>
    
    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>
</web-app>
 
页面：index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://blog.csdn.net/qjyong" prefix="q" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>PagerTag使用示例</title>
  </head>
  
  <body>
    <% 
      List<String> list = (List<String>)request.getAttribute("data");
      for(String str : list){
        out.println(str + "<br/>");
      }
    %>
    
    <q:pager pageNo="${pageNo}" 
                 recordCount="${recordCount}"
             pageSize="${pageSize}" 
             url="testpager" />
  </body>
</html>