Android-如何在后台进程中下载大量图片(http url大量) [英] Android - How to download a large nos of images (large nos of http url) in Background Process
问题描述
我从服务器获取图像URL列表,其数量大约在400-500之间.如何在后台将此图像下载到设备的本地文件夹中?
I am getting a list of image url from server whose count is approximately in between 400-500. How can i download this image in background into local folder of the device ?
到目前为止,我已经运行了前台服务,其中我正在使用ExecutorService运行线程.我的服务代码如下
SO far i have run a foreground service in which i am using ExecutorService to run a thread. My service code is below
public class SaveImageService extends Service {
private Context context;
public static final String NOTIFICATION_CHANNEL_ID = "10001";
public SaveImageService() {
}
@Override
public void onCreate() {
super.onCreate();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
startMyOwnForeground();
else
startForeground(1, new Notification());
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
context = this;
super.onStartCommand(intent, flags, startId);
List<Callable<String>> saveDataThreads = new ArrayList<>();
SaveTaskImage saveTaskImage = new SaveTaskImage(this);
saveDataThreads.add(saveTaskImage);
ExecutorService executor = Executors.newFixedThreadPool(saveDataThreads.size());
try {
List<Future<String>> aaa = executor.invokeAll(saveDataThreads);
} catch (InterruptedException e) {
e.printStackTrace();
}
executor.shutdown();
if (executor.isShutdown()) {
stopForeground(true);
stopSelf();
}
return START_STICKY;
}
@Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
throw new UnsupportedOperationException("Not yet implemented");
}
@RequiresApi(api = Build.VERSION_CODES.O)
private void startMyOwnForeground() {
String NOTIFICATION_CHANNEL_ID = "com.example.simpleapp";
String channelName = "My Background Service";
NotificationChannel chan = new NotificationChannel(NOTIFICATION_CHANNEL_ID, channelName, NotificationManager.IMPORTANCE_NONE);
chan.setLightColor(Color.BLUE);
chan.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);
NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
assert manager != null;
manager.createNotificationChannel(chan);
NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID);
Notification notification = notificationBuilder.setOngoing(true)
.setSmallIcon(R.mipmap.talentify_logo_red)
.setContentTitle("App is running in background")
.setPriority(NotificationManager.IMPORTANCE_MIN)
.setCategory(Notification.CATEGORY_SERVICE)
.build();
startForeground(2, notification);
}
}
在SaveTask线程中,我触发了如下同步任务
In SaveTask thread i triggering a sync task as below
new SaveImageAsync ("file_path").executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR,url);
下面是我的异步任务代码:
Below is my async task code :
public class SaveImageAsync extends AsyncTask<String, Void, String> {
private MediaSaver mediaSaver;
public SaveImageAsync(MediaSaver mediaSaver){
this.mediaSaver = mediaSaver;
}
@Override
protected String doInBackground(String... params) {
Bitmap bmp = null;
try{
System.out.println("Save image url --> "+params[0].replaceAll(" ", "%20"));
URL url = new URL(params[0].replaceAll(" ", "%20"));
InputStream fileInputStream = url.openStream();
if(fileInputStream != null) {
mediaSaver.save(fileInputStream);
System.out.println("Saving image --> ");
}else{
System.out.println("Not Saving image --> ");
}
}catch (Exception e){
e.printStackTrace();
}
return "";
}
@Override
protected void onPostExecute(String string) {
}
}
但是用这种方法,我只能在后台保存50 -60张图像.它一直运行到结束.我该怎么办建议
But in this approach i am able to save only 50 -60 images in background. Its not running till end. What should i do please suggest
推荐答案
在库下面使用-
implementation 'com.amitshekhar.android:android-networking:1.0.2'
该库的实现-
for (int j = 0; j < imageArrayList.size(); j++) {
downloadImage(imageArrayList.getImagePath(j), imageArrayList.get(j),getImageName);
}
private void downloadImage(String imageURL, String imagename) {
AndroidNetworking.download(imageURL, getCacheDir().getPath() + "/" + Constant.FOLDER_NAME + "/", imagename)
.setPriority(Priority.HIGH)
.build()
.setDownloadProgressListener(new DownloadProgressListener() {
@Override
public void onProgress(long bytesDownloaded, long totalBytes) {
// do anything with progress
}
})
.startDownload(new DownloadListener() {
@Override
public void onDownloadComplete() {
// do anything after completion
}
@Override
public void onError(ANError error) {
// handle error
}
});
}
您还可以使用android DownloadManager API. Android:如何使用下载管理器类?
You can also use android DownloadManager API. Android: How to use download manager class?
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