我目前有asynctask从服务器下载mp3。当用户开始下载时，会创建状态栏通知。这将实时显示下载进度。我唯一担心的是手机放慢了几乎。有没有办法延迟显示的进度或使我的代码更快的方法？感谢。
以下代码：
public class DownloadFile extends AsyncTask<String, String, String> {
CharSequence contentText;
Context context;
CharSequence contentTitle;
PendingIntent contentIntent;
int HELLO_ID = 1;
long time;
int icon;
CharSequence tickerText;
File file;
public void downloadNotification() {
String ns = Context.NOTIFICATION_SERVICE;
notificationManager = (NotificationManager) getSystemService(ns);
icon = R.drawable.sdricontest;
//the text that appears first on the status bar
tickerText = "Downloading...";
time = System.currentTimeMillis();
notification = new Notification(icon, tickerText, time);
context = getApplicationContext();
//the bold font
contentTitle = "Your download is in progress";
//the text that needs to change
contentText = "0% complete";
Intent notificationIntent = new Intent(Intent.ACTION_VIEW);
notificationIntent.setType("audio/*");
contentIntent = PendingIntent.getActivity(context, 0, notificationIntent, 0);
notification.setLatestEventInfo(context, contentTitle, contentText, contentIntent);
notificationManager.notify(HELLO_ID, notification);
}
@Override
protected void onPreExecute() {
//execute the status bar notification
downloadNotification();
super.onPreExecute();
}
@Override
protected String doInBackground(String... url) {
int count;
try {
URL url2 = new URL(sdrUrl);
HttpURLConnection connection = (HttpURLConnection) url2.openConnection();
connection.setRequestMethod("GET");
connection.setDoOutput(true);
connection.connect();
int lengthOfFile = connection.getContentLength();
//make the stop drop rave folder
File sdrFolder = new File(Environment.getExternalStorageDirectory() + "/StopDropRave");
boolean success = false;
if (!sdrFolder.exists()) {
success = sdrFolder.mkdir();
}
if (!success) {
String PATH = Environment.getExternalStorageDirectory()
+ "/StopDropRave/";
file = new File(PATH);
file.mkdirs();
} else {
String PATH = Environment.getExternalStorageDirectory()
+ "/StopDropRave/";
file = new File(PATH);
file.mkdirs();
}
String[] path = url2.getPath().split("/");
String mp3 = path[path.length - 1];
String mp31 = mp3.replace("%20", " ");
String sdrMp3 = mp31.replace("%28", "(");
String sdrMp31 = sdrMp3.replace("%29", ")");
String sdrMp32 = sdrMp31.replace("%27", "'");
File outputFile = new File(file, sdrMp32);
FileOutputStream fos = new FileOutputStream(outputFile);
InputStream input = connection.getInputStream();
byte[] data = new byte[1024];
long total = 0;
while ((count = input.read(data)) != -1) {
total += count;
publishProgress("" + (int) (total * 100 / lengthOfFile));
fos.write(data, 0, count);
}
fos.close();
input.close();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (IllegalStateException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
@Override
public void onProgressUpdate(String... progress) {
contentText = Integer.parseInt(progress[0]) + "% complete";
notification.setLatestEventInfo(context, contentTitle, contentText, contentIntent);
notificationManager.notify(HELLO_ID, notification);
super.onProgressUpdate(progress);
}
}
答案 0 :(得分：5)
我看到了类似的结果，你需要不经常推送更新通知，我改变我的更新只更新一次几次。 （例如，在onProgressUpdate中跟踪您上次呼叫通知的时间，并且只有在您超过上一次呼叫的100ms时，或者如果您处于最大值时才会呼叫通知。
答案 1 :(得分：4)
我曾遇到类似问题，我使用CountDownTimer解决了问题。
与@superfell的建议类似，您可以在下载文件时定期调用AsyncTask的进度更新。并且只在特定时间间隔调用通知管理器。
在调用CountDownTimer的start()之后，它将在每个固定的时间间隔后调用onTick()函数，并在计时器超时或显式调用时调用onFinish()。 cancel()函数只会取消计时器，不会调用onFinish()方法。
class DownloadMaterial extends AsyncTask<String, String, String> {
CountDownTimer cdt;
int id = i;
NotificationManager mNotifyManager;
NotificationCompat.Builder mBuilder;
@Override
protected void onPreExecute() {
/**
* Create custom Count Down Timer
*/
cdt = new CountDownTimer(100 * 60 * 1000, 500) {
public void onTick(long millisUntilFinished) {
mNotifyManager.notify(id, mBuilder.build());
}
public void onFinish() {
mNotifyManager.notify(id, mBuilder.build());
}
};
}
@Override
protected String doInBackground(String... strings) {
/**
* Start timer to update Notification
* Set Progress to 20 after connection
* Build Notification
* Increment Progress
* Download and Save file
*/
try {
mNotifyManager =
(NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
mBuilder = new NotificationCompat.Builder(context);
mBuilder.setContentTitle("Downloading File")
.setContentText(file_name)
.setProgress(0, 100, false)
.setOngoing(true)
.setSmallIcon(R.mipmap.ic_launcher)
.setPriority(Notification.PRIORITY_LOW);
// Initialize Objects here
publishProgress("5");
mNotifyManager.notify(id, mBuilder.build());
cdt.start();
// Create connection here
publishProgress("20");
// Download file here
while ((count = input.read(data)) != -1) {
total += count;
publishProgress("" + (int) (20 + (total * 80 / fileLength)));
output.write(data, 0, count);
}
} catch (Exception e) {
return "Failed";
}
return "Success";
}
@Override
protected void onProgressUpdate(String... values) {
/**
* Update Download Progress
*/
mBuilder.setContentInfo(values[0] + "%")
.setProgress(100, Integer.parseInt(values[0]), false);
}
@Override
protected void onPostExecute(String s) {
String title;
if (s.equals("Success")) {
title = "Downloaded";
} else {
title = "Error Occurred";
}
mBuilder.setContentTitle(title)
.setContentInfo("")
.setOngoing(false)
.setProgress(0, 0, false);
cdt.onFinish();
cdt.cancel();
}
}
最好先拨打onFinish()，然后拨打cancel()。
答案 2 :(得分：2)
我也遇到过这个问题。我经常更新进度条 WAY （即使进度没有改变），这是我如何修复：
// While loop from generic download method.
int previousProgress = 0;
while ((count = inputStream.read(buff)) != -1) {
outputStream.write(buff, 0, count);
totalBytesDownloaded += count;
int prog = (int) (totalBytesDownloaded * 100 / contentLength);
if (prog > previousProgress) {
// Only post progress event if we've made progress.
previousProgress = prog;
myPostProgressMethod(prog);
}
}
现在，应用程序运行良好，用户仍会收到进度通知。
答案 3 :(得分：0)
我遇到了同样的问题，即使间隔为3秒我也无法更新进度条通知，所以经过几个小时的挖掘后我才意识到每当我们更新通知时，RemoteView对象必须重新启动实例化并重新初始化为Notification对象的contentView。执行此操作后，我能够在很长一段时间内以100ms-500ms的间隔更新通知进度条，而不会遇到任何UI阻塞。
注意：如果您不同意，可以在注释掉标记的行并查看差异后运行此代码段来验证此答案。可能需要大约5分钟才能启动严重的UI阻塞，这会阻塞您的设备并可能停止运行。 我尝试使用Android 4.2.2的S3 mini，并且从服务中的工作线程调用updateNotification（....）方法。而且我已经仔细检查了它，并且不知道当Notification.Builder用于同一目的时会发生什么。
注意：在问题3年之后写这个答案的原因是因为我想知道我没有找到任何一个stackoverflow答案或其他博客文章处理这个非常简单的解决方案的严重问题。
我希望这个答案对像我这样的其他新手有所帮助。 享受。
这是我可以直接使用的复制粘贴代码.... 我使用相同的代码更新通知布局，其中包含两个ProgressBars和四个频率为500ms-100ms的TextView。
//long mMaxtTimeoutNanos = 1000000000 // 1000ms.
long mMinTimeNanos = 100000000;//100ms minimum update limit. For fast downloads.
long mMaxtTimeoutNanos = 500000000;//500ms maximum update limit. For Slow downloads
long mLastTimeNanos = 0;
private void updateNotification(.....){
// Max Limit
if (mUpdateNotification || ((System.nanoTime()-mLastTimeNanos) > mMaxtTimeoutNanos)) {
// Min Limit
if (((System.nanoTime() - mLastTimeNanos) > mMinTimeNanos)) {
mLastTimeNanos = System.nanoTime();
// instantiate new RemoteViews object.
// (comment out this line and instantiate somewhere
// to verify that the above told answer is true)
mRemoteView = new RemoteViews(getPackageName(),
R.layout.downloader_notification_layout);
// Upate mRemoteView with changed data
...
...
// Initialize the already existing Notification contentView
// object with newly instatiated mRemoteView.
mNotification.contentView = mRemoteView;
mNotificationManager.notify(mNotificatoinId, mNotification);
mUpdateNotification = false;
}
}
}