Upload multiple files at once using GWT-Collection of common programming errors

The solution is pretty simple. gwt-upload has a class Uploader which is able to do multiple uploads. The servlet code suggested in the wiki of gwt-upload is already capable of handling multiple uploads.

I had to change somethings in the Uploader class (source is fully available, so I just copied it and replaced the parts I needed). To access filenames and filesizes of the selected files I created a simple native method:

private static native String getFilesSelected() /*-{
    var count = $wnd.$('input:file')[0].files.length;

    var out = "";

    for (i = 0; i < count; i++) {
        var file = $wnd.$('input:file')[0].files[i];
        out += file.name + ';' + file.size + ";";
    return out;

whichs return value I split by ; to get the needed results.

And you need to replace the uploaders FileInput (setFileInput()) with a custom one, which sets the multiple property to the input. I use a wrapper class like this:

public class MyFileInput implements IFileInput {

    private final FileUpload fu;

    public MyFileInput() {
        fu = new FileUpload();
        DOM.setElementProperty(fu.getElement(), "multiple", "multiple");    

you obviously need to implement the other methods of IFileInput, I linked them all through to fu. Two had no equivalent method, but I dont use them, so no problem here …

Originally posted 2013-11-09 19:45:05.