From Gossip@caterpillar

Struts Gossip: 訊息管理

在Struts中可以在一個訊息資源檔中統一管理訊息，您可以在struts-config.xml中設定資源檔名稱及位置，例如：
  • struts-config.xml
<?xml version="1.0" encoding="ISO-8859-1" ?>

<!DOCTYPE struts-config PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 1.2//EN"
"http://jakarta.apache.org/struts/dtds/struts-config_1_2.dtd">
<struts-config>
    <action-mappings>
        <action
             path="/hello" 
             type="onlyfun.caterpillar.HelloAction"> 
             <forward
                 name="helloUser" 
                 path="/WEB-INF/pages/hello.jsp"/> 
         </action>
     </action-mappings>
    
    <message-resources parameter="resources/messages"/>
</struts-config>

在<message-resources>標籤中設定了資源檔位置為 resources/messages，這表示將使用CLASSPATH下的resources/messages.properties檔案，例如您可 以將之放在/WEB-INF/classes/resources/messages.properties下，資源檔內容如下：
  • messages.properties
welcome.helloWord=Hello!
welcome.message=This is your secret gift!!

配合訊息資源檔，來寫個簡單的 Action 測試一下訊息管理：
  • HelloAction.java
package onlyfun.caterpillar;

import java.util.*;
import javax.servlet.http.*;
import org.apache.struts.action.*;
import org.apache.struts.util.MessageResources;

public class HelloAction extends Action {
    public ActionForward execute(
                             ActionMapping mapping, 
                             ActionForm form, 
                             HttpServletRequest request, 
                             HttpServletResponse response) 
                                     throws Exception {
        
        MessageResources messageResources = 
                             getResources(request);
        
        String helloWord = 
           messageResources.getMessage("welcome.helloWord");
        String message = 
           messageResources.getMessage("welcome.message");
        
        // get information from request object
        String username = request.getParameter("user");
        
        // prepare model
        Map model = new HashMap();
        model.put("helloWord", helloWord);
        model.put("message", message);
        
        if(username != null)
            model.put("username", username);
        else
            model.put("username", "nobody");
        
        // pass information to View by using reqeust object
        request.setAttribute("userInfo", model);
        
        // no more carrying information from client
        request.removeAttribute("user");
        
        return mapping.findForward("helloUser");
    }
}

這邊使用繼承Action下來的getResources()取得一個MessageResources物件，當中包括了 messages.properties的訊息，然後使用它的getMessage()指定鍵值來取得對應訊息，來寫一個簡單的JSP網頁測試一下：
  • hello.jsp
<html> 
<head> 
<title>
     ${userInfo["helloWord"]} ${userInfo["username"]}!
</title> 
</head> 
<body>

 <H1>${userInfo["helloWord"]} ${userInfo["username"]} !</H1> 
 <H1>${userInfo["message"]}</H1>                                

</body> 
</html>

依上面的設定，如果依下面的方式請求：
http://localhost:8080/strutsapp/hello.do?user=Justin

則將傳回以下的結果：
<html>
<head>
<title>
     Hello! Justin !
</title>
</head>
<body>

<H1>Hello! Justin !</H1>
<H1>This is your secret gift!!</H1>

</body>
</html>