java - 为什么 IntentReceiverLeaked？

Question

我想从蓝牙服务器接收一个 String，它是 pc 我有一个 java 代码，但是当我运行我的 Android 客户端 Activity 时，它会显示这个异常

Activity com.waseem.mobileclient.bluetoot_app.MainActivity has leaked IntentReceiver com.waseem.mobileclient.bluetoot_app.MainActivity$1@410480f0 that was originally registered here. Are you missing a call to unregisterReceiver()?
android.app.IntentReceiverLeaked: Activity com.waseem.mobileclient.bluetoot_app.MainActivity has leaked IntentReceiver com.waseem.mobileclient.bluetoot_app.MainActivity$1@410480f0 that was originally registered here. Are you missing a call to unregisterReceiver()?
        at android.app.LoadedApk$ReceiverDispatcher.<init>(LoadedApk.java:792)
        at android.app.LoadedApk.getReceiverDispatcher(LoadedApk.java:593)
        at android.app.ContextImpl.registerReceiverInternal(ContextImpl.java:1111)
        at android.app.ContextImpl.registerReceiver(ContextImpl.java:1098)
        at android.app.ContextImpl.registerReceiver(ContextImpl.java:1092)
        at android.content.ContextWrapper.registerReceiver(ContextWrapper.java:365)
        at com.waseem.mobileclient.bluetoot_app.MainActivity.onCreate(MainActivity.java:68)
        at android.app.Activity.performCreate(Activity.java:5008)

我在 onPause() 中注销 为什么我会收到此异常 请帮帮我 这让我困扰了很长时间。这是客户端代码

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    if (myBluetoothAdapter == null) {
        Log.e(TAG, "No Bluetooth Adapter available. Exiting...");
        this.finish();
    }
    IntentFilter intent_filter=new IntentFilter(MESSAGE_RECEIVED_INTENT);
    broad_receiver=new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            if (intent.getAction().equals(MESSAGE_RECEIVED_INTENT)) {
                showInformation(intent.getExtras().getString("Message"), 5000);
                getVibrator().vibrate(500);
            }
            else {
                showInformation("Message unable to receive", 5000);
                getVibrator().vibrate(500);
            }
        }
    };

    this.registerReceiver(broad_receiver,intent_filter);
    Button start_server = (Button)findViewById(R.id.button_start);
    start_server.setOnClickListener(this);

    Button stop_server = (Button)findViewById(R.id.button_stop);
    stop_server.setOnClickListener(this);

}

@Override
protected void onPause() {
    this.unregisterReceiver(this.broad_receiver);
    super.onPause();

    server.cancel();
    restoreBTDeviceName();

}

@Override
public void onClick(View v) {
    Button btn = (Button) v;
    if (btn.getId() == R.id.button_start) {
        if (!myBluetoothAdapter.getName().startsWith(PREFIX))
            myBluetoothAdapter.setName(PREFIX );

        if (myBluetoothAdapter.getScanMode() != BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE) {
            requestBTDiscoverable();
            server = new AcceptThread();
            server.start();

            btn.setEnabled(false);

            ((Button) this.findViewById(R.id.button_stop)).setEnabled(true);
        }
    } else if (btn.getId() == R.id.button_stop) {
        server.cancel();
        btn.setEnabled(false);
        ((Button) this.findViewById(R.id.button_start)).setEnabled(true);

        restoreBTDeviceName();
    }

}

/**
 * Launches Discoverable Bluetooth Intent.
 */
public void requestBTDiscoverable() {
    Intent i = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
    i.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);

    startActivityForResult(i, REQUEST);

    int result = 0;

    this.onActivityResult(REQUEST, result, i);
    Log.i(TAG, "Bluetooth discoverability enabled");
}

/**
 * Obtains the Vibrator service.
 *
 * @return Vibrator Object.
 */
private Vibrator getVibrator() {

    return (Vibrator) getSystemService(VIBRATOR_SERVICE);
}

/**
 * Removes the prefix from the device name if the prefix is present.
 */
private void restoreBTDeviceName() {
    if (myBluetoothAdapter.getName().startsWith(PREFIX))
        myBluetoothAdapter.setName(myBluetoothAdapter.getName().substring(PREFIX.length()));
}

/**
 * Shows a information dialog.
 *
 * @param message  String resource used to define the message.
 * @param duration Dialog's TTL.
 */
private void showInformation(String message, long duration) {
    final Dialog mDialog = new Dialog(this);

    TextView txt = new TextView(this);
    txt.setText(message);
    mDialog.setContentView(txt);
    mDialog.setTitle("Information");
    mDialog.show();

    (new Handler()).postDelayed(new Runnable() {
        public void run() {
            mDialog.dismiss();
        }
    },duration); // Close dialog after delay
}


/**
 * ************************************* AcceptThread *************************************
 */
class AcceptThread extends Thread {
    /**
     * Tag that will appear in the log.
     */
    private final String ACCEPT_TAG = AcceptThread.class.getName();

    /**
     * The bluetooth server socket.
     */
    private final BluetoothServerSocket mServerSocket;

    public AcceptThread() {
        BluetoothServerSocket tmp = null;
        try {
            tmp = myBluetoothAdapter.listenUsingRfcommWithServiceRecord(ACCEPT_TAG, UUID.fromString(defaultUUID));
        } catch (IOException e) {
            e.printStackTrace();
        }
        mServerSocket = tmp;
    }

    public void run() {
        BluetoothSocket socket = null;
        while (true) {
            try {
                Log.i(ACCEPT_TAG, "Listening for a connection...");

                socket = mServerSocket.accept();
                Log.i(ACCEPT_TAG, "Connected to " + socket.getRemoteDevice().getName());

            } catch (IOException e) {
                break;
            }
            // If a connection was accepted
            if (socket != null) {
                // Do work to manage the connection (in a separate thread)
                try {
                    // Read the incoming string.
                    String buffer;

                    DataInputStream in = new DataInputStream(socket.getInputStream());

                    buffer = in.readUTF();

                    Intent i = new Intent(MESSAGE_RECEIVED_INTENT);
                    i.putExtra("Message", String.format("%sn From: %s", buffer, socket.getRemoteDevice().getName()));

                    getBaseContext().sendBroadcast(i);
                } catch (IOException e) {
                    Log.e(ACCEPT_TAG, "Error obtaining InputStream from socket");
                    e.printStackTrace();
                }
                try {
                    mServerSocket.close();
                } catch (IOException e) {
                }
                break;
            }
        }

    }

    /**
     * Will cancel the listening socket, and cause the thread to finish
     */
    public void cancel() {
        try {
            mServerSocket.close();
        } catch (IOException e) {
        }
    }
}

Answer 1

LogCat 的第一行说:

Are you missing a call to unregisterReceiver()?

简单的说就是需要查看BroadcastReceiver的API文档寻求帮助，上面写着:

Note: If registering a receiver in your Activity.onResume() implementation, you should unregister it in Activity.onPause(). (You won't receive intents when paused, and this will cut down on unnecessary system overhead). Do not unregister in Activity.onSaveInstanceState(), because this won't be called if the user moves back in the history stack.