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Android是一种基于Linux的自由及开放源代码的操作系统,主要使用于移动设备,如智能手机和平板电脑,由Google公司和开放手机联盟领导及开发。尚未有统一中文名称,中国大陆地区较多人使用“安卓”或“安致”。
这篇文章主要介绍了Android基于自带的DownloadManager实现下载功能,结合实例形式分析了DownloadManager实现下载功能的具体操作步骤与相关注意事项,需要的朋友可以参考下
本文实例讲述了Android基于自带的DownloadManager实现下载功能。分享给大家供大家参考,具体如下:
- 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);
是加入下载请求到下载管理类中,并且会返回一个下载的ID。
- downloadManager.enqueue
- request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI);
大文件只能在wifi下下载
需要注册一个下载完成的广播,自定义这个广播
- 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);
- }
- }
- }
- };
这里的
的
- intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);
是DownloadManager类里的参数,使用下面方法注册广播
- DownloadManager.EXTRA_DOWNLOAD_ID
- /** register download success broadcast **/
- registerReceiver(completeReceiver, new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));
用到的IntentFilter是下载完成的Filter
然后会通知这个广播,并且返回的intent里面包含了
的参数。
- DownloadManager.EXTRA_DOWNLOAD_ID
关于DownloadManager的其他用法可以查看api文档
这里再介绍下DownloadManager.Query的用法。
显而易见Query是内部类。有
和
- query.setFilterById
两个方法,
- query.setFilterByStatus
query.setFilterById就是把downloadManager.enqueue返回的id放进去作为查询的条件;
- query.setFilterByStatus(DownloadManager.STATUS_FAILED | DownloadManager.STATUS_PENDING | DownloadManager.STATUS_RUNNING | DownloadManager.STATUS_SUCCESSFUL);
可以进行拼接查询的条件。
- Cursor cur = downloadManager.query(query);
这里用的Query查询Downloads的数据库,但是只可以查询本应用下载的数据
- /**
- * 使用DownloadManager.Query查询Downloads的DB,但是在stackoverflow中的解释是
- * 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.
- */
所以要是想通过
查询系统所有的下载记录是不可行的。
- DownloadManager.Query
但是需求有要怎么办呢?
记得ApiDemo里有用户联系人使用Uri的方式查询联系人contacts,进入Root Explore观察com.android.providers.downloads包里的DB数据库内容时,发现下载的记录里有content://media/external/file/452122
这种内容,所以可以这样获取到下载的文件
- Cursor cursor = getContentResolver().query(Uri.parse("content://media/external/file"), null, null, null, null);
测试下返回的字段
- /*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);
- }
根据自己需求提取字段。
希望本文所述对大家Android程序设计有所帮助。
来源: http://www.phperz.com/article/17/0913/345807.html