Android(安卓)自带的DownloadManager 在Service 中下载 apk 安装

在Android 中如果请求网络，数据量小的时候，可以使用Volley 库，但是如果是下载数据非常大时，变的不可行了。这时我们可以使用Andoid 自带的 DownloadManager ，只要是api 9以上都可以用。网上也有很多例子，但是大部分都是放在Activity 中，这样带来很多的不便。当我们下载大文件时必须在这个界面。所以，我就根据网上的例子，自己改造了一下，把下载放在Service 中，用来下载apk 安装。

1、首先，拿到启动Service 时传过来的下载Url , DownloadManager 下载后会发出一个广播，所以我们同时注册下载完成的广播；

Intent intent = new Intent(MainActivity.this, DownloadRecommdAppService.class);intent.putExtra(DownloadRecommdAppService.DOWNLOAD_URL, url);startService(intent);

2、因为 Service 也是运行在主线程中的，所以，我们把下载这些耗时的工作另开线程进行。

3、在广播中，通过判断下载的状态，如果下载成功，就启动安装apk, 同时停止 Service.

public class DownloadRecommdAppService extends Service{public static final String DOWNLOAD_URL = "download_url";public static final String DOWNLOAD_FOLDER_NAME = "download";public  static final String DOWNLOAD_FILE_NAME = "yxhuang.apk";@Overridepublic IBinder onBind(Intent intent) {return null;}@Overridepublic int onStartCommand(Intent intent, int flags, int startId) {if (intent != null) {String downloadUrl = intent.getExtras().getString(DOWNLOAD_URL);if (downloadUrl != null) {// 注册下载完成广播DownloadCompleteReceiver completeReceiver = new DownloadCompleteReceiver();registerReceiver(completeReceiver, new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));// 下载new Thread(new DownloadRunable(downloadUrl)).start();}}return super.onStartCommand(intent, flags, startId);}// 下载class DownloadRunable implements Runnable{private String mDownloadUrl;public DownloadRunable(String url) {mDownloadUrl = url;}@Overridepublic void run() {startDownload();}// 开始下载private void startDownload(){File folder = Environment.getExternalStoragePublicDirectory(DOWNLOAD_FOLDER_NAME);if (!folder.exists() || !folder.isDirectory()) {folder.mkdirs();}DownloadManager manager = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);DownloadManager.Request request = new DownloadManager.Request(Uri.parse(mDownloadUrl));request.setMimeType("application/vnd.android.package-archive");// 存储的目录request.setDestinationInExternalPublicDir(DOWNLOAD_FOLDER_NAME, DOWNLOAD_FILE_NAME);// 设定只有在 WIFI 情况下才能下载request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI);request.setTitle("下载应用");request.setVisibleInDownloadsUi(true);manager.enqueue(request);}}// 下载完成 class DownloadCompleteReceiver extends BroadcastReceiver {@Overridepublic void onReceive(Context context, Intent intent) { long completeDownloadId = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);if (intent.getAction() == DownloadManager.ACTION_DOWNLOAD_COMPLETE) {checkStatus(context, completeDownloadId);}}private void checkStatus(Context context,Long completeDownloadId){    DownloadManager mManager  = (DownloadManager) context.getSystemService(Service.DOWNLOAD_SERVICE);DownloadManager.Query query = new DownloadManager.Query();query.setFilterById(completeDownloadId);Cursor cursor = mManager.query(query);if (cursor.moveToFirst()) {int status = cursor.getInt(cursor.getColumnIndex(DownloadManager.COLUMN_STATUS));switch (status) {case DownloadManager.STATUS_RUNNING:break;case DownloadManager.STATUS_SUCCESSFUL:Toast.makeText(context, "下载成功", Toast.LENGTH_SHORT).show(); String apkFilePath = new StringBuilder(Environment.getExternalStorageDirectory().getAbsolutePath())                 .append(File.separator).append(DownloadRecommdAppService.DOWNLOAD_FOLDER_NAME).append(File.separator)                 .append(DownloadRecommdAppService.DOWNLOAD_FILE_NAME).toString(); installApk(context, apkFilePath);  // 停止下载Service DownloadRecommdAppService.this.stopSelf();break;default:break;}}cursor.close();}// 安装APkprivate  void installApk(Context context, String file) {File apkFile = new File(file);Intent intent = new Intent(Intent.ACTION_VIEW);intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);intent.setDataAndType(Uri.fromFile(apkFile), "application/vnd.android.package-archive");context.startActivity(intent);}}}

关于 DownloadManager 详细的介绍，移步至 http://www.trinea.cn/android/android-downloadmanager/

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