CODEWITHSUNDEEP
gwt
Forkmohit
Forkmohit

Reputation: 753

GWT : Get file upload speed to display progress bar

I have a written a Servlet for uploading the file. On the UI, I want to display a progress bar for the file upload in GWT. How to get file upload speed?

Upvotes: 0

Views: 514

Answers (1)

Thomas Broyer
Thomas Broyer

Reputation: 64561

The only way to do it without relying on some server-side helper with "server push" is to send the form or file using XMLHttpRequest and using its progress events (supported basically everywhere but IE, so you'd need to fallback to a basic form in IE). To do that with GWT, you have to use JSNI though.

If you absolutely need to support IE (and by that I mean display upload progress, because you could easily degrade gracefully to a standard form upload), you'd need the server to tell the client about the progress; that means you need a back-channel with "server push". The easiest is to use GWTUpload then or some similar third-party library.

For display, you can use a <progress> element. In GWT, the easiest is to use it through UiBinder within an HTMLPanel: bind it to an Element @UiField and modify its properties with setPropertyDouble et al. It's relatively easy to create a Widget around a progress element created through Document.get().createElement("progress"). Or you can use a third-party library (GWT-Bootstrap or else) or create a progress bar out of <div> elements and CSS. Again, it depends which browsers you want/need to support.

Upvotes: 3

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