幾次迭代后線程被殺死

Question

我正在嘗試創建一個包含服務的應用程序，該服務在設備啟動時啟動，然后記錄一些事件。

manifest.xml中的服務條目

<receiver android:name="com.myservices.BReceiver" >
    <intent-filter>
        <action android:name="android.intent.action.BOOT_COMPLETED" />

        <category android:name="android.intent.category.HOME" />
    </intent-filter>
</receiver>
<service android:name="com.myservices.MyService" >
</service>

BReceiver.java

public class BReceiver extends BroadcastReceiver {

    private static final String TAG = "BReceiver";

    @Override
    public void onReceive(Context context, Intent intent) {
        Log.e(TAG, "onReceive started");
        // Main Logging Service
        Intent service = new Intent(context, MyService.class);
        context.startService(service);
        Log.e(TAG, "onReceive ended");
    }

}

MService.class

public class MyService extends IntentService {

    private static final String TAG = "MyService";
    private static final long TIMER = 2000;

    public MyService() {
        super("MyService");
    }

    @Override
    protected void onHandleIntent(Intent intent) {

        startLogginThread();

    }

    /**
     * For logging
     */
    private void startLogginThread() {
        Thread thread = new Thread() {
            public void run() {
                while (true) {
                    try {

                        // Logging events
                        myLogger();
                        Log.e(TAG, "Awake");
                        // TIMER
                        Thread.sleep(TIMER);
                    } catch (Exception e) {
                        Log.e("MyService", "local Thread error "+ e.toString());
                    }
                }
            }
        };
        thread.start();
    }

    private void myLogger() {

        // Creating new file to store logs.
        // Check if SD card is available else use internal memory.
        File dir = null;
        if (MyServiceUtil.isExternalStorageReadable() && MyServiceUtil.isExternalStorageWritable()) {
            // External Memory
            File sdCard = Environment.getExternalStorageDirectory();
            dir = new File(sdCard.getAbsolutePath() + "/MyLogger");
            dir.mkdirs();
        } else {
            // Internal Memory
            dir = getFilesDir();
        }

        // Rename to txt for reading
        File file = new File(dir, "log.txt");

        if (!file.exists()) {
            try {
                file.createNewFile();
            } catch (IOException e) {
                Log.e(TAG, "Exception :" + e.toString());
            }
        }

        // Printing timestamp in file
        try {

            PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter(file, true)));
            String timeStamp = new SimpleDateFormat("dd.MM.yyyy '-' HH:mm:ss").format(Calendar.getInstance().getTime());
            out.println(timeStamp);

            // Log Location

            out.close();
            Log.e("Logggging", timeStamp);
        } catch (IOException e) {
            Log.e(TAG, "Exception :" + e.toString());
        }

    }

    @Override
    public void onDestroy() {
        Log.e(TAG, "onDestroy called");
        super.onDestroy();
    }

}

結果：僅打印幾次日志，例如6-7次，並將日志存儲在文件中。 下面是日志：

11-16 17:00:02.438: E/BReceiver(3187): onReceive started
11-16 17:00:02.438: E/BReceiver(3187): onReceive ended
11-16 17:00:02.458: E/MyService(3187): onDestroy called
11-16 17:00:02.458: D/MyServiceUtil(3187): isExternalStorageReadable started
11-16 17:00:02.468: D/MyServiceUtil(3187): isExternalStorageWritable started
11-16 17:00:02.468: E/Logggging(3187): 16.11.2014 - 17:00:02
11-16 17:00:02.468: E/MyService(3187): Awake
11-16 17:00:04.468: D/MyServiceUtil(3187): isExternalStorageReadable started
11-16 17:00:04.468: D/MyServiceUtil(3187): isExternalStorageWritable started
11-16 17:00:04.478: E/Logggging(3187): 16.11.2014 - 17:00:04
11-16 17:00:04.478: E/MyService(3187): Awake
11-16 17:00:06.478: D/MyServiceUtil(3187): isExternalStorageReadable started
11-16 17:00:06.488: D/MyServiceUtil(3187): isExternalStorageWritable started
11-16 17:00:06.488: E/Logggging(3187): 16.11.2014 - 17:00:06
11-16 17:00:06.488: E/MyService(3187): Awake
11-16 17:00:08.488: D/MyServiceUtil(3187): isExternalStorageReadable started
11-16 17:00:08.488: D/MyServiceUtil(3187): isExternalStorageWritable started
11-16 17:00:08.488: E/Logggging(3187): 16.11.2014 - 17:00:08
11-16 17:00:08.488: E/MyService(3187): Awake

另外，如果線程已經在運行，我不明白為什么調用onDestroy：

11-16 17：00：02.458：E / MyService（3187）：onDestroy被調用

PS-這僅在Kitkat中發生。

Answer 1

要在BroadcastReceiver中執行后台任務，您需要調用goAsync（） ，sdk 11+，並在完成后調用PendingResult.finish（）

可以由onReceive（Context，Intent）中的應用程序調用此方法，以使其從該函數返回后保持廣播活動。 這不會改變對廣播做出相對響應的期望（在10秒內完成），但是允許實現將與廣播有關的工作移到另一個線程上，以避免由於磁盤IO造成主UI線程故障。

您可以在接收器中移動代碼並使用goAsync，也可以直接在IntentService中運行代碼，因為它與Service不同，它具有自己的后台線程。

更新資料

final PendingResult pendingResult = goAsync();

new Thread() {
    public void run() {
        while (SOME_CONDITION) {
            try {
                // Logging events
                myLogger();
                Log.e(TAG, "Awake");
                // TIMER
                Thread.sleep(TIMER);
            } catch (Exception e) {
                Log.e("MyService", "local Thread error "+ e.toString());
            }
        }

        // Finish the broadcast.
        pendingResult.finish();
    }
}.start();

Answer 2

您對IntentService不太了解。 onHandleIntent的方法是在框架啟動的子線程中調用的，當onHandleIntent完成時，該服務將自行終止，因此原因是您將作業放在了啟動的新線程中。 因此，您應該將代碼放入onHandleIntent中。

while (true) {
  try {

     // Logging events
     myLogger();
     Log.e(TAG, "Awake");
     // TIMER
     Thread.sleep(TIMER);
  } catch (Exception e) {
    Log.e("MyService", "local Thread error "+ e.toString());
  }
}