本文實(shí)例講述了Android基于自帶的DownloadManager實(shí)現(xiàn)下載功能。分享給大家供大家參考，具體如下：
DownloadManager.Request request = new DownloadManager.Request(Uri.parse(APK_URL));request.setDestinationInExternalPublicDir(DOWNLOAD_FOLDER_NAME, DOWNLOAD_FILE_NAME);request.setTitle(getString(R.string.download_notification_title));request.setDescription("meilishuo desc");request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);request.setVisibleInDownloadsUi(false);// request.allowScanningByMediaScanner();// request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI);// request.setShowRunningNotification(false);// request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_HIDDEN);request.setMimeType("application/cn.trinea.download.file");downloadId = downloadManager.enqueue(request);downloadManager.enqueue是加入下載請(qǐng)求到下載管理類中，并且會(huì)返回一個(gè)下載的ID。
request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI);
大文件只能在wifi下下載
需要注冊(cè)一個(gè)下載完成的廣播，自定義這個(gè)廣播
class CompleteReceiver extends BroadcastReceiver { @Override public void onReceive(Context context, Intent intent) { /** * get the id of download which have download success, if the id is my id and it's status is successful, * then install it **/ long completeDownloadId = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1); if (completeDownloadId == downloadId) { initData(); updateView(); // if download successful, install apk if (downloadManagerPro.getStatusById(downloadId) == DownloadManager.STATUS_SUCCESSFUL) { String apkFilePath = new StringBuilder(Environment.getExternalStorageDirectory().getAbsolutePath()) .append(File.separator).append(DOWNLOAD_FOLDER_NAME).append(File.separator) .append(DOWNLOAD_FILE_NAME).toString(); install(context, apkFilePath); } } } };這里的intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);的DownloadManager.EXTRA_DOWNLOAD_ID是DownloadManager類里的參數(shù)，使用下面方法注冊(cè)廣播
/** register download success broadcast **/registerReceiver(completeReceiver, new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));
用到的IntentFilter是下載完成的Filter
然后會(huì)通知這個(gè)廣播，并且返回的intent里面包含了DownloadManager.EXTRA_DOWNLOAD_ID的參數(shù)。
關(guān)于DownloadManager的其他用法可以查看api文檔
這里再介紹下DownloadManager.Query的用法。
顯而易見Query是內(nèi)部類。有query.setFilterById和query.setFilterByStatus兩個(gè)方法，
query.setFilterById就是把downloadManager.enqueue返回的id放進(jìn)去作為查詢的條件；
可以進(jìn)行拼接查詢的條件。
Cursor cur = downloadManager.query(query);
這里用的Query查詢Downloads的數(shù)據(jù)庫，但是只可以查詢本應(yīng)用下載的數(shù)據(jù)
/** * 使用DownloadManager.Query查詢Downloads的DB，但是在stackoverflow中的解釋是 * You can't access this DB from my application. For your own downloads, * use DownloadManager.Query to check on your download status. Data about downloads is not shared to other apps. */
所以要是想通過DownloadManager.Query查詢系統(tǒng)所有的下載記錄是不可行的。
但是需求有要怎么辦呢？
記得ApiDemo里有用戶聯(lián)系人使用Uri的方式查詢聯(lián)系人contacts，進(jìn)入Root Explore觀察com.android.providers.downloads包里的DB數(shù)據(jù)庫內(nèi)容時(shí)，發(fā)現(xiàn)下載的記錄里有content://media/external/file/452122
這種內(nèi)容，所以可以這樣獲取到下載的文件
測試下返回的字段
/*String[] downNames = cursor.getColumnNames();String str = "";for(int i=0;i<downNames.length;i++){ str += downNames[i]+",";}*/if(cursor!=null&&cursor.moveToLast()){// cursor.moveToPrevious() String displayname = cursor.getString(cursor.getColumnIndex("_display_name")); String name = cursor.getString(cursor.getColumnIndex("name")); String title = cursor.getString(cursor.getColumnIndex("title")); String description = cursor.getString(cursor.getColumnIndex("description")); String data = cursor.getString(cursor.getColumnIndex("_data")); String bucket = cursor.getString(cursor.getColumnIndex("bucket_display_name")); downloadTip.setText(displayname+","+name+","+title+","+description+","+data+","+bucket);}根據(jù)自己需求提取字段。
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希望本文所述對(duì)大家Android程序設(shè)計(jì)有所幫助。
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