如何在android 2.2中创建自己的下载管理器
我知道我们可以在安卓2.3及以上版本中使用内置下载管理器,但我的应用程序适合安卓2.2及以上版本。我的问题是如何在安卓2.2中创建自己的下载管理器?请给我一些示例答案 请给我一些示例答案 步骤1查看如何在Android中下载文件的示例 步骤2查看如何在AsyncTask中执行操作的示例 步骤3查看下载时如何显示下载进度的示例 步骤4查看任务完成时如何发送自定义广播的示例 步骤5查看如何即使在设备旋转的情况下仍保持AsysncTask操作的示例 步骤6查看如何在通知中显示下载进度的示例 下面是示例代码 1。使用AsyncTask并在对话框中显示下载进度如何在android 2.2中创建自己的下载管理器,android,Android,我知道我们可以在安卓2.3及以上版本中使用内置下载管理器,但我的应用程序适合安卓2.2及以上版本。我的问题是如何在安卓2.2中创建自己的下载管理器?请给我一些示例答案 请给我一些示例答案 步骤1查看如何在Android中下载文件的示例 步骤2查看如何在AsyncTask中执行操作的示例 步骤3查看下载时如何显示下载进度的示例 步骤4查看任务完成时如何发送自定义广播的示例 步骤5查看如何即使在设备旋转的情况下仍保持AsysncTask操作的示例 步骤6查看如何在通知中显示下载进度的示例 下面是示例
// declare the dialog as a member field of your activity
ProgressDialog mProgressDialog;
// instantiate it within the onCreate method
mProgressDialog = new ProgressDialog(YourActivity.this);
mProgressDialog.setMessage("A message");
mProgressDialog.setIndeterminate(false);
mProgressDialog.setMax(100);
mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
// execute this when the downloader must be fired
DownloadFile downloadFile = new DownloadFile();
downloadFile.execute("the url to the file you want to download");
The AsyncTask will look like this:
// usually, subclasses of AsyncTask are declared inside the activity class.
// that way, you can easily modify the UI thread from here
private class DownloadFile extends AsyncTask<String, Integer, String> {
@Override
protected String doInBackground(String... sUrl) {
try {
URL url = new URL(sUrl[0]);
URLConnection connection = url.openConnection();
connection.connect();
// this will be useful so that you can show a typical 0-100% progress bar
int fileLength = connection.getContentLength();
// download the file
InputStream input = new BufferedInputStream(url.openStream());
OutputStream output = new FileOutputStream("/sdcard/file_name.extension");
byte data[] = new byte[1024];
long total = 0;
int count;
while ((count = input.read(data)) != -1) {
total += count;
// publishing the progress....
publishProgress((int) (total * 100 / fileLength));
output.write(data, 0, count);
}
output.flush();
output.close();
input.close();
} catch (Exception e) {
}
return null;
}
2。从服务下载
这里的大问题是:如何从服务更新我的活动?。在下一个示例中,我们将使用两个您可能不知道的类:ResultReceiver和IntentService。ResultReceiver允许我们从服务更新线程;IntentService是服务的一个子类,它生成一个线程来执行后台工作(您应该知道服务实际上在应用程序的同一线程中运行;当您扩展服务时,必须手动生成新线程来运行CPU阻塞操作)
下载服务可以如下所示:
public class DownloadService extends IntentService {
public static final int UPDATE_PROGRESS = 8344;
public DownloadService() {
super("DownloadService");
}
@Override
protected void onHandleIntent(Intent intent) {
String urlToDownload = intent.getStringExtra("url");
ResultReceiver receiver = (ResultReceiver) intent.getParcelableExtra("receiver");
try {
URL url = new URL(urlToDownload);
URLConnection connection = url.openConnection();
connection.connect();
// this will be useful so that you can show a typical 0-100% progress bar
int fileLength = connection.getContentLength();
// download the file
InputStream input = new BufferedInputStream(url.openStream());
OutputStream output = new FileOutputStream("/sdcard/BarcodeScanner-debug.apk");
byte data[] = new byte[1024];
long total = 0;
int count;
while ((count = input.read(data)) != -1) {
total += count;
// publishing the progress....
Bundle resultData = new Bundle();
resultData.putInt("progress" ,(int) (total * 100 / fileLength));
receiver.send(UPDATE_PROGRESS, resultData);
output.write(data, 0, count);
}
output.flush();
output.close();
input.close();
} catch (IOException e) {
e.printStackTrace();
}
Bundle resultData = new Bundle();
resultData.putInt("progress" ,100);
receiver.send(UPDATE_PROGRESS, resultData);
}
}
将服务添加到您的清单:
<service android:name=".DownloadService"/>
以下是ResultReceiver来玩的结果:
private class DownloadReceiver extends ResultReceiver{
public DownloadReceiver(Handler handler) {
super(handler);
}
@Override
protected void onReceiveResult(int resultCode, Bundle resultData) {
super.onReceiveResult(resultCode, resultData);
if (resultCode == DownloadService.UPDATE_PROGRESS) {
int progress = resultData.getInt("progress");
mProgressDialog.setProgress(progress);
if (progress == 100) {
mProgressDialog.dismiss();
}
}
}
}
谢谢你的回复。我会试试这个。如果它解决了你的问题,别忘了接受答案,因为它会帮助其他用户,
mProgressDialog.show();
Intent intent = new Intent(this, DownloadService.class);
intent.putExtra("url", "url of the file to download");
intent.putExtra("receiver", new DownloadReceiver(new Handler()));
startService(intent);
private class DownloadReceiver extends ResultReceiver{
public DownloadReceiver(Handler handler) {
super(handler);
}
@Override
protected void onReceiveResult(int resultCode, Bundle resultData) {
super.onReceiveResult(resultCode, resultData);
if (resultCode == DownloadService.UPDATE_PROGRESS) {
int progress = resultData.getInt("progress");
mProgressDialog.setProgress(progress);
if (progress == 100) {
mProgressDialog.dismiss();
}
}
}
}