Struts 1.3.8 Action實現類中消息的輸出及JSP頁面中消息標簽的使用總結

(1) Action中保存消息及錯誤的簡單實現：
……
//此處是ActionMessages是帶’s’的類名
ActionMessages messages = new ActionMessages();
//向messages添加一個消息對象，并設定property為“sucess”
messages.add(“sucess”, new ActionMessage(“source.key”));
//將消息集合保存到request中，并以“org.apache.struts.action.ACTION_MESSAGE”為關鍵字；此方法可在下面看到Action類中實現的源代碼
saveMessages(request,messages);
//將消息集合保存到request中，并以“org.apache.struts.action.ERROR”為關鍵字；此方法可在下面看到Action類中實現的源代碼
saveErrors(request,messages);
……
(2) Struts 1.3.8中的Action中保存消息和錯誤的源代碼如下：
protected void addMessages(HttpServletRequest request, ActionMessages messages)
{
if (messages == null)
return;
ActionMessages requestMessages = (ActionMessages)request.getAttribute("org.apache.struts.action.ACTION_MESSAGE");
if (requestMessages == null)
requestMessages = new ActionMessages();
requestMessages.add(messages);
if (requestMessages.isEmpty())
{
request.removeAttribute("org.apache.struts.action.ACTION_MESSAGE");
return;
} else
{
request.setAttribute("org.apache.struts.action.ACTION_MESSAGE", requestMessages);
return;
}
}

protected void addErrors(HttpServletRequest request, ActionMessages errors)
{
if (errors == null)
return;
ActionMessages requestErrors = (ActionMessages)request.getAttribute("org.apache.struts.action.ERROR");
if (requestErrors == null)
requestErrors = new ActionMessages();
requestErrors.add(errors);
if (requestErrors.isEmpty())
{
request.removeAttribute("org.apache.struts.action.ERROR");
return;
} else
{
request.setAttribute("org.apache.struts.action.ERROR", requestErrors);
return;
}
}
(3) JSP頁面中用和標簽輸出：
……

……
MessagesTag的實現類構造如下：
public MessagesTag()
{
iterator = null;
processed = false;
id = null;
bundle = null;
locale = "org.apache.struts.action.LOCALE";
name = "org.apache.struts.action.ERROR";
property = null;
header = null;
footer = null;
message = null;
}