java麪包屑導航製作

做了個簡單的麪包屑導航功能,比如頁面上大家經常看到的這種導航： 
 
您所在的位置：音樂社區-->用戶模塊-->用戶註冊 
 
我做成了標籤的形式，利用jom4j來解析xml文件：
 
核心類SiteMapTag.java： 

Java代碼  
 

package com.market.common;

import java.io.InputStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

/**
 * 站點導航標籤的實現 
 * <p>
 * Title: SiteMapTag.java
 * </p>
 * <p>
 * Description:
 * </p>
 * <p>
 * Copyright: Copyright (c) 2012
 * </p>
 * 
 * @author  fjs
 * @version   Sep 15, 2012
 */
public class SiteMapTag extends TagSupport {

	private static final long serialVersionUID = -3531938467909884528L;
	private String currentFilePath;
	private Element target;
	
	@Override
	public int doStartTag() throws JspException {
		HttpServletRequest request = (HttpServletRequest) this.pageContext.getRequest();
		currentFilePath = request.getRequestURI().replaceFirst(request.getContextPath(), "");
		try {
			Element root = (Element)pageContext.getServletContext().getAttribute("webSiteMapSet");
			if(root==null){
				SAXReader reader = new SAXReader();
				InputStream inputStream = SiteMapTag.class.getClassLoader().getResourceAsStream("sitemap.xml");
				Document document = reader.read(inputStream);
				root = document.getRootElement();
				pageContext.getServletContext().setAttribute("webSiteMapSet", root);
			}
			parseParent(root);
			StringBuffer content = new StringBuffer("");
			List<String> titles = new ArrayList<String>();
			List<String> hrefs = new ArrayList<String>();
			
			while(target!=null){
				Attribute attTitle = target.attribute("title");
				if(attTitle!=null){
					titles.add(attTitle.getText());
				}
				
				Attribute attHref = target.attribute("href");
				if(attHref!=null){
					hrefs.add(attHref.getText());
				}else{
					hrefs.add("");
				}
				
				target = target.getParent();
			}
			
			for (int i = titles.size()-1; i >=0; i--) {
				String href = hrefs.get(i);
				if(href.equals("")){
					content.append(titles.get(i)+" - ");
				}else{
					content.append("<a href='"+href+"'>"+titles.get(i)+"</a> - ");
				}
			}
			if(content.length()>0){
				this.pageContext.getOut().println(content.delete(content.length()-3, content.length()));
			}
		} catch (Exception e) {
			e.printStackTrace();
			throw new JspException(e);
		}
		
		
		return super.doStartTag();
	}

	private void parseParent(Element parent){
		Iterator<Element> it = parent.elementIterator();
		while(it.hasNext()){
			Element temp = it.next();
			Attribute attr = temp.attribute("path");
			if(attr!=null){
				if(attr.getText().equals(currentFilePath)){
					target = temp;
					return;
				}
			}
			parseParent(temp);
		}
	}
	
}

 sitemap.tld文件（存放在WEB-INF\tlds下）：
Xml代碼  
 

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

<taglib xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd"
    version="2.1">

    <description>站點導航標籤</description>
	<display-name>myTaglib siteMap</display-name>
	<tlib-version>1.1</tlib-version>    
    <short-name>tagUtil</short-name>
    <uri>http://tag.market.org/jsp/tagutil/sitemap</uri>

    <tag>
		<description>麪包屑標籤</description>
		<name>siteMap</name>
		<tag-class>com.market.common.SiteMapTag</tag-class>
		<body-content>empty</body-content>
    </tag>
    
</taglib>

 
 在項目的src下面添加sitemap.xml文件：
 
Xml代碼 
<?xml version="1.0" encoding="UTF-8"?>  

<!-- 配置文件說明， sitemap根節點,title是頁面上顯示的內容，  
   href是超鏈接，path是該請求頁面的物理路徑 
--> 
<sitemap title="音樂社區" href="index.action">  
    <node  title="用戶模塊">  
        <node path="/WEB-INF/pages/user/register_view.jsp" href="user/registerView.action"  title="用戶註冊" />  
    </node> 
</sitemap>  
  
 
要使用的jsp頁面加入標籤指令：

<%@taglib uri="http://tag.forever.org/jsp/tagutil/sitemap" prefix="tagUtil" %> 

 

如果運行報找不到 tld文件就在web.xml的web-app節點下加入

<jsp-config>
  <taglib>
   <taglib-uri>/sitemap.tld</taglib-uri>
   <taglib-location>/WEB-INF/tlds/sitemap.tld</taglib-location>
  </taglib>
 </jsp-config>

那在jsp的標籤指令需要改爲  <%@taglib uri="/sitemap.tld" prefix="tagUtil" %>

 在想放的位置處加上標籤：
 
您所在的位置：<tagUtil:siteMap/> 就可以出現麪包屑導航了。