Grab the direct link from mediafire on Android

MediaFireLoader.java

/*
 * Copyright (C) 2014 Jared Rummler <jared@jrummyapps.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.jrummyapps.utils.webview;

import android.annotation.SuppressLint;
import android.content.Context;
import android.webkit.JsResult;
import android.webkit.WebChromeClient;
import android.webkit.WebView;
import android.webkit.WebViewClient;

/**
 * Loads a mediafire URL in a {@link WebView} and then gets the direct download link.
 * <br><br>Example usage:
 * <pre>
 * <code>final String url = "http://www.mediafire.com/download/v24hhydvijc7o0c/test.zip";
 * 
 * new MediaFireLoader(context).load(url, new MediaFireLoader.Callback() {
 * 	
 * 	{@literal @}Override
 * 	public void onFailed() {
 * 		// The url loaded but no download link was found.
 * 	}
 * 	
 * 	{@literal @}Override
 * 	public void onDownloadLinkFound(String downloadLink) {
 * 	    // We successfully found the direct download link.
 * 	}
 * });
 * </code>
 * </pre>
 * 
 * @author Jared Rummler
 */
public class MediaFireLoader {

	private static final String MESSAGE_NO_DOWNLOAD_LINK = "NO_DOWNLOAD_LINK_FOUND";

	/**
	 * Callback that gets invoked when the URL is done loading in the {@link WebView}
	 */
	public interface Callback {
		/**
		 * 
		 * @param downloadLink The value of href for the Download button that usually shows on mediafire.
		 */
		void onDownloadLinkFound(String downloadLink);
		/**
		 * Called when no download link was found
		 */
		void onFailed();
	}

	private Context mContext;

	public MediaFireLoader(Context context) {
		mContext = context;
	}

	/**
	 * Load a mediafire URL in a {@link WebView} and attempt to retrieve the download link.
	 * 
	 * @param url		A URL to a file hosted on https://www.mediafire.com/
	 * @param callback	The {@link Callback} that gets invoked after the page is loaded.
	 */
	@SuppressLint("SetJavaScriptEnabled")
	public void load(final String url, final Callback callback) {
		final WebView webView = new WebView(mContext);
		webView.getSettings().setJavaScriptEnabled(true);
		// Allow the WebView to show alerts and handle those alerts
		webView.setWebChromeClient(new WebChromeClient() {
			@Override
			public boolean onJsAlert(WebView view, String url, String message, JsResult result) {
				result.confirm();
				if (message.equals(MESSAGE_NO_DOWNLOAD_LINK)) {
					callback.onFailed();
					return true;
				}
				callback.onDownloadLinkFound(message);
				return true;
			}
		});
		// WebViewClient must be set before calling loadUrl to inject JavaScript
		webView.setWebViewClient(new WebViewClient() {
			@Override
			public void onPageFinished(WebView view, String url) {
				webView.loadUrl("javascript:(function() { "
						+ "  var v = document.getElementsByClassName(\"download_link\");"
						+ "  if (v.length > 0) {"
						+ "    var a = v[0].getElementsByTagName(\"a\");"
						+ "    if (a.length > 0) {"
						+ "      var link = a[0];"
						+ "      alert(link.href);" // Send the download link as an alert
						+ "      return;"
						+ "    }"
						+ "  }"
						+ "  alert(\"" + MESSAGE_NO_DOWNLOAD_LINK + "\");"
						+ "})()");  
			}
		});
		webView.loadUrl(url);
	}
}