jsp开发迭代标签一
     第一步:编写一个标签处理器类
public class ForeachTag1 extends SimpleTagSupport {
	//用来作为关键字存放值
	private String var;
	private Object items;
	public void setVar(String var) {
		this.var = var;
	}
	public void setItems(Object items) {
		this.items = items;
	}
	public void doTag() throws JspException, IOException {	
		List list=(List)items;
		Iterator iterator=list.iterator();
		while(iterator.hasNext())
		{
			Object obj=iterator.next();
			this.getJspContext().setAttribute(var, obj);
			this.getJspBody().invoke(null);
		}
	}
}
第二步:WEB-INF 目录下编写一个*.tld标签描述文件
<?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>A tag library exercising SimpleTag handlers.</description>
    <tlib-version>1.0</tlib-version>
    <short-name>SimpleTagLibrary</short-name>
    <uri>http://www.liyong.foreach1tag</uri>
   <tag>
    <name>foreach1</name>
    <tag-class>com.liyong.foreach.ForeachTag1</tag-class>   
    <body-content>scriptless</body-content> 
    <attribute>
    	<name>items</name>
    	<required>true</required>
    	<rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
    	<name>var</name>
    	<required>true</required>
    	<rtexprvalue>false</rtexprvalue>
    </attribute>
	</tag>  	
	<tag>	
</taglib>
第三步:编写jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib uri="http://www.liyong.foreach1tag" prefix="foreach"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">    
    <title>My JSP 'foreach1.jsp' starting page</title> 
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
  </head>  
  <body> <br>
    <%
	List list=new ArrayList();
	list.add("aaa");
	list.add("bbb");
	list.add("ccc");
	list.add("ddd");
	request.setAttribute("list",list);
 %>
 <foreach:foreach1 var="str" items="${list}" >
 	${str }
 </foreach:foreach1>
  </body>
</html>
第四步:测试...