FileUploader.java

package fr.lteconsulting.hexa.client.ui.uploadjs;

import java.util.ArrayList;
import java.util.Date;
import java.util.Map;
import java.util.Map.Entry;

import com.google.gwt.core.client.JavaScriptException;

public class FileUploader
{
	public interface Callback
	{
		void onStart();

		void onProgress( int percentage, float speed, String response );
	}

	public void uploadFile( String url, Map<String, String> parameters, String name, File file, Callback callback )
	{
		tasks.add( new UploadTask( url, parameters, name, file, callback ) );

		processNextTask();
	}

	class UploadTask
	{
		UploadTask( String url, Map<String, String> parameters, String name, File file, Callback callback )
		{
			this.url = url;
			this.parameters = parameters;
			this.name = name;
			this.file = file;
			this.callback = callback;
		}

		String url;
		String name;
		File file;
		Map<String, String> parameters;
		Callback callback;

		void launch()
		{
			file.getAsBinary( new File.Callback()
			{
				public void onDataReady( String data )
				{
					realUpload( data );
				}
			} );
		}

		void realUpload( Object binaryData )
		{
			String boundary = "AJAX------" + Math.random() + "" + new Date().getTime();

			final XMLHttpRequestEx req = XMLHttpRequestEx.create();
			req.open( "POST", url );
			req.setRequestHeader( "Content-Type", "multipart/form-data; boundary=" + boundary );

			String CRLF = "\r\n";

			String data = "--" + boundary + CRLF;

			data += "Content-Disposition: form-data; ";
			data += "name=\"" + name + "\"; ";
			data += "filename=\"" + file.getFileName() + "\"; " + CRLF;
			data += "Content-Type: " + file.getMimeType();
			data += CRLF + CRLF;
			data += binaryData + CRLF;

			if( parameters != null )
			{
				for( Entry<String, String> e : parameters.entrySet() )
				{
					data += "--" + boundary + CRLF;

					data += "Content-Disposition: form-data; ";
					data += "name=\"" + e.getKey() + "\"" + CRLF + CRLF;
					data += e.getValue() + CRLF;
				}
			}

			data += "--" + boundary + "--" + CRLF;

			try
			{
				final TransfertSpeedCalculator transfertSpeedCalculator = new TransfertSpeedCalculator();
				transfertSpeedCalculator.startTransfert( data.length() );

				callback.onStart();
				req.sendAsBinary( data, new XMLHttpRequestEx.Callback()
				{
					@Override
					public void onProgress( int percentage )
					{
						float speed = transfertSpeedCalculator.getSpeed( percentage );

						callback.onProgress( percentage, speed, req.getResponseText() );

						if( percentage < 0 || percentage == 100 )
						{
							currentTask = null;
							processNextTask();
						}
					}
				} );
			}
			catch( JavaScriptException e )
			{
				callback.onProgress( -1, 0, null );

				currentTask = null;
				processNextTask();
			}
		}
	}

	UploadTask currentTask = null;
	ArrayList<UploadTask> tasks = new ArrayList<UploadTask>();

	void processNextTask()
	{
		if( currentTask != null )
			return;
		if( tasks.isEmpty() )
			return;

		currentTask = tasks.remove( 0 );
		currentTask.launch();
	}
}

class TransfertSpeedCalculator
{
	int dataSize;
	long startTime;

	public TransfertSpeedCalculator()
	{
	}

	public void startTransfert( int dataSize )
	{
		this.dataSize = dataSize;
		startTime = new Date().getTime();
	}

	public float getSpeed( int percentage )
	{
		if( percentage <= 0 )
			return 0;

		int bytesTransferred = (dataSize * percentage) / 100;
		long transfertTime = new Date().getTime() - startTime;

		if( transfertTime == 0 )
			return 0; // prevent divide by zero

		float coef = 1000.0f / 1024.0f;
		float speed = coef * ((float) (bytesTransferred) / (float) (transfertTime)); // en
																						// ko/s

		return speed;
	}
}