Vaadin自定义服务器通知消息

Vaadin内部定义了很多通知信息，包括session过期，服务器错误等。

 

这些信息保存在Application中的静态类SystemMessage中

 protected String sessionExpiredURL = null;
        protected boolean sessionExpiredNotificationEnabled = true;
        protected String sessionExpiredCaption = "Session Expired";
        protected String sessionExpiredMessage = "Take note of any unsaved data, and <u>click here</u> to continue.";

        protected String communicationErrorURL = null;
        protected boolean communicationErrorNotificationEnabled = true;
        protected String communicationErrorCaption = "Communication problem";
        protected String communicationErrorMessage = "Take note of any unsaved data, and <u>click here</u> to continue.";

        protected String authenticationErrorURL = null;
        protected boolean authenticationErrorNotificationEnabled = true;
        protected String authenticationErrorCaption = "Authentication problem";
        protected String authenticationErrorMessage = "Take note of any unsaved data, and <u>click here</u> to continue.";

        protected String internalErrorURL = null;
        protected boolean internalErrorNotificationEnabled = true;
        protected String internalErrorCaption = "Internal error";
        protected String internalErrorMessage = "Please notify the administrator.<br/>Take note of any unsaved data, and <u>click here</u> to continue.";

        protected String outOfSyncURL = null;
        protected boolean outOfSyncNotificationEnabled = true;
        protected String outOfSyncCaption = "Out of sync";
        protected String outOfSyncMessage = "Something has caused us to be out of sync with the server.<br/>Take note of any unsaved data, and <u>click here</u> to re-sync.";

        protected String cookiesDisabledURL = null;
        protected boolean cookiesDisabledNotificationEnabled = true;
        protected String cookiesDisabledCaption = "Cookies disabled";
        protected String cookiesDisabledMessage = "This application requires cookies to function.<br/>Please enable cookies in your browser and <u>click here</u> to try again.";

 通过Application的静态方法getSystemMessages可以返回SystemMessage类。

另外提供CustomizedSystemMessages类来自定义信息，该类继承子 SystemMessage

 

由于java不能重写静态方法所以 vaadin的做法是如果在继承记Application的子类中 有getSystemMessages的静态方法存在的话就调用该方法。

 

这样就可以通过提供getSystemMessages的静态方法返回CustomizedSystemMessages对象来实现自定义消息

public static SystemMessages getSystemMessages() {
		 Application.CustomizedSystemMessages m = new Application.CustomizedSystemMessages();
		 m.setCommunicationErrorCaption("通信失败，服务器没有响应");
		 m.setSessionExpiredMessage(" 长时间没有操作session过期，保存好当前页面数据, <u>点击这里</u>继续.");
	     return m;
	 }