自定义迭代标签实现-优快云博客

本文介绍了一个自定义的JSP迭代标签IterateTag的实现方式，该标签允许开发者通过设置属性来迭代显示数组中的元素。文章详细展示了IterateTag类的代码及如何在JSP页面中使用此标签。

IterateTag.java

package tag;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;

/**
 * @作者 :goby
 * @创建时间：2009-6-14 下午04:47:43
 * @更新时间:$Date$
 */
public class IterateTag extends TagSupport {
	
	String name;
	String[] items;
	int i = 1;
	
	public void setName(String name) {
		this.name = name;
	}

	public void setItems(String[] items){
		this.items = items;
	}
	/* (non-Javadoc)
	 * @see javax.servlet.jsp.tagext.TagSupport#doStartTag()
	 */
	@Override
	public int doStartTag() throws JspException {
		// TODO Auto-generated method stub
		
		if(items!=null && items.length>0){
			pageContext.setAttribute(name, items[0]);
			//把标签体的执行结果插入到输出流中
			return EVAL_BODY_INCLUDE;
		}
		return super.doStartTag();
	}

//	不再重复执行标签内容
	@Override
	public int doAfterBody() throws JspException {
		  if(i<items.length){
			  pageContext.setAttribute(name, items[i]);
			  i++;
			  return EVAL_BODY_AGAIN;//重复执行标签内容
		  }else{
			  return SKIP_BODY; //不再重复执行标签内容
		  }
	}
	
    
	
}

tag.tld

<?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 web-jsptaglibrary_2_0.xsd"  
    version="2.0">

	<tlib-version>1.0</tlib-version>
	<short-name>it315</short-name>
	<uri>/taglib</uri>	
	<tag>
		<name>iterate</name>
		<tag-class>tag.IterateTag</tag-class>
		<attribute>
			<name>name</name>
			<requried>true</requried>
		</attribute>
		<attribute>
			<name>items</name>
			<requried>true</requried>
			<rtexprvalue>true</rtexprvalue>
		</attribute>
	</tag>
</taglib>

index.jsp

<%@ page contentType="text/html; charset=gb2312" %>
<%@ taglib uri="/taglib" prefix="it315" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
    <head>
        <title>Hello</title>
    </head>
    <body>
            <br>
      iterate:
      <br>
	<% String[] books = {"dsdeeeee","123","ss","dd"}; %>
	<it315:iterate name="bookname" items="<%=books %>">
	<%=pageContext.findAttribute("bookname") %>
		${bookname}<br>
	</it315:iterate>
    </body>
    
</html>