基础使用：

DownloadManager.Request request;try{    request = new DownloadManager.Request(Uri.parse("String url"));    // 放入下载队列    Context appContext = getApplicationContext();    DownloadManager manager = (DownloadManager)appContext.getSystemService(Context.DOWNLOAD_SERVICE);    manager.enqueue(request);}catch (Exception e){    e.printStackTrace();    return;}

加入下载队列后可以获得一个下载ID用于创建下载进度观察者或者下载完成的广播通知

long downloadId = manager.enqueue(request);

下载进度观察者:

final DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);getContentResolver().registerContentObserver(Uri.parse("content://downloads/my_downloads"), true, new ContentObserver(new Handler()) {    @Override    public void onChange(boolean selfChange) {        int[] bytesAndStatus = new int[]{-1, -1, 0};        DownloadManager.Query query = new DownloadManager.Query().setFilterById(downloadId);        Cursor cursor = null;        try {            cursor = dm.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));                //计算下载进度                float progress = (float)bytesAndStatus[0]/bytesAndStatus[1];                                // 当进度完全执行好了记得 注销观察者 不注销的话 可能会多跑几次                if(progress == 1){                    getContentResolver().unregisterContentObserver(this);                }            }        } finally {            if (cursor != null) {                cursor.close();            }        }    }});

注册广播接收者

IntentFilter intentFilter = new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE);BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {    @Override    public void onReceive(Context context, Intent intent) {        long ID = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);        if (ID == downloadId) {            // 执行完成后的代码            Toast.makeText(getApplicationContext(), "任务:" + downloadId + " 下载完成!", Toast.LENGTH_LONG).show();            // 记得注销广播接收者  不注销的话这个会一直在的            unregisterReceiver(this);        }    }};registerReceiver(broadcastReceiver, intentFilter);

其他：

1.保存路径问题

request.setDestinationInExternalPublicDir("保存路径","保存的文件名称");

2.通知栏显示下载信息

request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE);request.setTitle("下载");request.setDescription("应用正在下载");request.setAllowedOverRoaming(false);

3.个人使用目的：下载apk，完成后调用安装

String serviceString = Context.DOWNLOAD_SERVICE;DownloadManager dManager = (DownloadManager) context.getSystemService(serviceString);// 根据下载管理获取下载文件的URI 自己写Uri.pase("文件路径")也是可以的Uri downloadFileUri = dManager.getUriForDownloadedFile(downloadId);Intent intent = new Intent(Intent.ACTION_VIEW);intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION); // 该语句会授予临时的访问权限 否则会秒退intent.setDataAndType(fileuri, "application/vnd.android.package-archive");startActivity(intent);