Progress bar for File Uploading?

Question

I am using servlets to upload files in my web application. I want to show progress bar while uploading. I have went through some Ajax+Progresslistener examples, one here .

In the doPost() method they creates a Session Object and Sets a new attribute Listener. Apart from that my previous code and tutorials code for doPost() method is same.

My question is they are setting the Listener Attribute one time, at the beginning. How it will update the bytesRead frequently My question is they are setting the Listener Attribute one time, at the beginning. How it will update the bytesRead frequently (I am new to this, So, my questions maybe unreasonable)

In the doGet() method they retrieve the Listener Attribute and Extracts the needed information from it.

This part also, i am not able to understand. They are not implementing ProgressListener class(Searches, led me to this Class).

I know some DWR. So, i can use it to get the data transfer information from server, if i understood server side process to update the data transfer.

Shall any one explain me the server side process?

Or Any Links or Suggestions would be Appreciative at the moment!!!

Thanks!

Answer 1

类似的线程， 带有进度条的Java文件上传 。