downloadManager = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
downloadObserver = new DownloadChangeObserver();
//在执行下载前注册内容监听者
registerContentObserver();
DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
/**设置用于下载时的网络状态*/
request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI | DownloadManager.Request.NETWORK_MOBILE);
/**设置通知栏是否可见*/
request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_HIDDEN);
/**设置漫游状态下是否可以下载*/
request.setAllowedOverRoaming(false);
/**如果我们希望下载的文件可以被系统的Downloads应用扫描到并管理，
我们需要调用Request对象的setVisibleInDownloadsUi方法，传递参数true.*/
request.setVisibleInDownloadsUi(true);
/**设置文件保存路径*/
request.setDestinationInExternalFilesDir(getApplicationContext(), "phoenix", "phoenix.apk");
/**将下载请求放入队列， return下载任务的ID*/
downloadId = downloadManager.enqueue(request);
//执行下载任务时注册广播监听下载成功状态
registerBroadcast();

<!--网络通信权限-->
<uses-permission android:name="android.permission.INTERNET"/>
<!--SD卡写入数据权限-->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<!--SD卡创建与删除权限-->
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<!--VISIBILITY_HIDDEN表示不显示任何通知栏提示的权限-->
<uses-permission android:name="android.permission.DOWNLOAD_WITHOUT_NOTIFICATION"/>
<!--DownloadManager-->
<uses-permission android:name="android.permission.ACCESS_DOWNLOAD_MANAGER"/>
在清单文件中注册Service
<!--版本更新服务-->
<service android:name="com.github.phoenix.service.DownloadService"></service>

/**
* 注册ContentObserver
*/
private void registerContentObserver() {
 /** observer download change **/
 if (downloadObserver != null) {
   getContentResolver().registerContentObserver(Uri.parse("content://downloads/my_downloads"), true, downloadObserver);
 }
}

/**
* 监听下载进度
*/
private class DownloadChangeObserver extends ContentObserver {

 public DownloadChangeObserver() {
   super(downLoadHandler);
   scheduledExecutorService = Executors.newSingleThreadScheduledExecutor();
 }

 /**
  * 当所监听的Uri发生改变时，就会回调此方法
  *
  * @param selfChange 此值意义不大, 一般情况下该回调值false
  */
 @Override
 public void onChange(boolean selfChange) {
   scheduledExecutorService.scheduleAtFixedRate(progressRunnable, 0, 2, TimeUnit.SECONDS);
 }
}
/**
* 通过query查询下载状态，包括已下载数据大小，总大小，下载状态
*
* @param downloadId
* @return
*/
private int[] getBytesAndStatus(long downloadId) {
 int[] bytesAndStatus = new int[]{
     -1, -1, 0
 };
 DownloadManager.Query query = new DownloadManager.Query().setFilterById(downloadId);
 Cursor cursor = null;
 try {
   cursor = downloadManager.query(query);
   if (cursor != null && cursor.moveToFirst()) {
     //已经下载文件大小
     bytesAndStatus[0] = cursor.getInt(cursor.getColumnIndexOrThrow(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR));
     //下载文件的总大小
     bytesAndStatus[1] = cursor.getInt(cursor.getColumnIndexOrThrow(DownloadManager.COLUMN_TOTAL_SIZE_BYTES));
     //下载状态
     bytesAndStatus[2] = cursor.getInt(cursor.getColumnIndex(DownloadManager.COLUMN_STATUS));
   }
 } finally {
   if (cursor != null) {
     cursor.close();
   }
 }
 return bytesAndStatus;
}

private ServiceConnection conn = new ServiceConnection() {

 @Override
 public void onServiceConnected(ComponentName name, IBinder service) {
   DownloadService.DownloadBinder binder = (DownloadService.DownloadBinder) service;
   DownloadService downloadService = binder.getService();

   //接口回调，下载进度
   downloadService.setOnProgressListener(new DownloadService.OnProgressListener() {
     @Override
     public void onProgress(float fraction) {
       LogUtil.i(TAG, "下载进度：" + fraction);
       bnp.setProgress((int)(fraction * 100));

       //判断是否真的下载完成进行安装了，以及是否注册绑定过服务
       if (fraction == DownloadService.UNBIND_SERVICE && isBindService) {
         unbindService(conn);
         isBindService = false;
         MToast.shortToast("下载完成！");
       }
     }
   });
 }

 @Override
 public void onServiceDisconnected(ComponentName name) {

 }
};

/**
* 安装APK
* @param context
* @param apkPath 安装包的路径
*/
public static void installApk(Context context, Uri apkPath) {
 Intent intent = new Intent();
 intent.setAction(Intent.ACTION_VIEW);
 //此处因为上下文是Context，所以要加此Flag，不然会报错
 intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
 intent.setDataAndType(apkPath, "application/vnd.android.package-archive");
 context.startActivity(intent);
}

/**
* 删除上次更新存储在本地的apk
*/
private void removeOldApk() {
 //获取老ＡＰＫ的存储路径
 File fileName = new File(SPUtil.getString(Constant.SP_DOWNLOAD_PATH, ""));
 LogUtil.i(TAG, "老APK的存储路径 =" + SPUtil.getString(Constant.SP_DOWNLOAD_PATH, ""));

 if (fileName != null && fileName.exists() && fileName.isFile()) {
   fileName.delete();
   LogUtil.i(TAG, "存储器内存在老APK，进行删除操作");
 }
}