Java 上载文件时处理网络问题

这里是迄今为止生成的html（使用

GWT

作为前端），这是我迄今为止复制GWT类的html

这相当于

 .submit(function(){
   //handle file response
})

很好

问题是，如果internet断开连接，在上载文件时，浏览器不会抛出

错误/异常/响应

我想通知用户，有一个网络问题

但浏览器会一直提交表单，而不会从该状态返回

有什么提示吗

谢谢您的时间。
如果事件为空，是否签入处理程序

form.addSubmitCompleteHandler(new FormPanel.SubmitCompleteHandler() {
        public void onSubmitComplete(SubmitCompleteEvent event) {
            if(event != null){
                   Window.alert("Upload OK!");
            }else
                   Window.alert("Upload fail");
    });

但我认为如果你有网络问题，SubmitCompleteEvent永远不会被解雇

解决方案可以是在提交文件时设置计时器：

public class ViewWidget {

Form form;
Timer timer = new Timer() {
     @Override
     public void run() {
         Window.alert("Troubles with upload! Try again!");
     }
 };

 public ViewWidget(){
     form.addSubmitHandler(new SubmitHandler() {

        @Override
        public void onSubmit(SubmitEvent event) {
            timer.schedule(10000);
        }
    });

     form.addSubmitCompleteHandler(new SubmitCompleteHandler() {

        @Override
        public void onSubmitComplete(SubmitCompleteEvent event) {
            //Cancel the timer
            timer.cancel();

            if(event != null){
                //Do your Stuff
                Window.alert("Upload Ok !");
            }else
                Window.alert("Upload Fails");
        }
    });
 }

我不尝试代码，但它应该可以工作

希望能有帮助

form.addSubmitCompleteHandler(new FormPanel.SubmitCompleteHandler() {
        public void onSubmitComplete(SubmitCompleteEvent event) {
            if(event != null){
                   Window.alert("Upload OK!");
            }else
                   Window.alert("Upload fail");
    });

public class ViewWidget {

Form form;
Timer timer = new Timer() {
     @Override
     public void run() {
         Window.alert("Troubles with upload! Try again!");
     }
 };

 public ViewWidget(){
     form.addSubmitHandler(new SubmitHandler() {

        @Override
        public void onSubmit(SubmitEvent event) {
            timer.schedule(10000);
        }
    });

     form.addSubmitCompleteHandler(new SubmitCompleteHandler() {

        @Override
        public void onSubmitComplete(SubmitCompleteEvent event) {
            //Cancel the timer
            timer.cancel();

            if(event != null){
                //Do your Stuff
                Window.alert("Upload Ok !");
            }else
                Window.alert("Upload Fails");
        }
    });
 }