jsp/javaでパンくず自動生成 - 技術いろいろ @ ウィキ

参考サイト;
http://blog.goo.ne.jp/glass-_-onion/e/6f86c9903ce7c75ebd5d56b827724961
http://www.hellohiro.com/customtag.htm

• 参考サイトをもとにリンクつけつつ、特定のアクションのみパンくずに表示するよう書いてみました

前提

• strutsベース
• actionクラスは一度baseのアクションを作成し、必ず継承する。

(1)baseアクションに以下のように記述

//サブシステムで実装するクラス。
protected abstract String execute(ActionForm frm);

public ActionForward execute(ActionMapping map, ActionForm frm,
        HttpServletRequest request, HttpServletResponse response) {
    String result = execute(frm);

   //パンくず処理開始
    ActionStack stack = (ActionStack)request.getSession().getAttribute("ForwardStack");
   //新規作成
    if(stack == null) {
      stack = new ActionStack();
   }
  //すでに登録済みかチェック
   int index = stack.search(request.getServletPath());
 
  if(index == -1) {
     //-1=未登録
      //新規push
     stack.push(request.getServletPath());
  } else {
     //既登録
      //登録してある箇所から後ろを除去
      for(int i = 0; i < index - 1; i++) {
       stack.pop();
     }
  }
  //セッションに設定
  request.getSession().setAttribute("ForwardStack", stack);
  return map.findForward(result);
}

(2)ActionStack.javaを作成

import java.util.Iterator;
import java.util.Stack;

public class ActionStack {
   Stack forwardStack = new Stack();
   Stack forwardNmStack = new Stack();
   //パンくず対象
   private static final String[] targetActionArr = {"/topInit.do","/search.do","/detailInit.do"};

   private static final String[] targetActionNmArr = {"トップ画面","検索画面 ","詳細画面"};
    
   public String pop() {
   	forwardNmStack.pop();
       return (String)forwardStack.pop();
   }
   public void push(String path) {
   	String actiomcanPush = canPush(path);
   	if(null != actiomcanPush){
   		 forwardStack.push(path);
   		 forwardNmStack.push(actiomcanPush);
       }
   }
 
   public boolean empty() {
   	
       return forwardNmStack.empty();
   }
   public int search(String path) {
       int index = forwardStack.size();
       for(Iterator i = forwardStack.iterator(); i.hasNext(); index--) {
       	String forward = (String)i.next();
           if(path.equals(forward)) {
               return index;
           }
       }
       return -1;
   }
   public Iterator iterator() {
       return forwardNmStack.iterator();
   }	
   public int size() {
       return forwardNmStack.size();
   }

   private String canPush(String path){
   	int i = 0;
   	for(String targetAction:targetActionArr){
   		if(targetAction.equals(path)){
   			StringBuilder buf = new StringBuilder();
   			buf.append("<a href=\"."+path+"\">");
   			buf.append(targetActionNmArr[i]+"</a>");
   			return buf.toString();
   		}
   		i++;
   	}
   	return null;
   }
}

(3)TopicPathTag.javaを作成

import java.io.IOException;
import java.util.Iterator;

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

import org.apache.struts.taglib.TagUtils;
//ActionStackもインポート

@SuppressWarnings("serial")
public class TopicPathTag extends TagSupport {

   public int doStartTag() throws JspException {
       ActionStack stack = (ActionStack)TagUtils.getInstance().lookup(
           pageContext, "ForwardStack", "session");
       StringBuilder buf = new StringBuilder();
       for(Iterator i = stack.iterator(); i.hasNext();) {
           String forward = (String)i.next();
           buf.append(forward);
           buf.append("　>　");
       }
       buf.deleteCharAt(buf.lastIndexOf(">"));
       try {	
           JspWriter out = pageContext.getOut();
           out.print(buf);
       } catch (IOException e) {
           throw new JspException(e);
       }
       return SKIP_BODY;
   }
}

(4)TLDファィルを作成(ファィル名は任意)

<?xml version="1.0" encoding="Shift_JIS" ?>
<!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library   1.1//EN" "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd"> 
<taglib>
 <tlibversion>1.0</tlibversion>
 <jspversion>1.1</jspversion>
 <shortname>org</shortname>

 <tag>
   <name>TopicPath</name>
   <!-タグクラスを指定-->
   <tagclass>jp.co.sample.TopicPathTag</tagclass>
   <bodycontent>empty</bodycontent>
   <info>パンくず</info>
 </tag>

</taglib>