我有一个连接屏幕，我有一个搜索按钮，点击它后发布了可发现的设备列表，我点击所需的设备进行配对和连接，建立连接，当我锁定屏幕连接丢失了，我怎样才能改进我的代码以使服务仍然有效？这就是我尝试实现它的方法，onCreate（），onStart（）和onResume（）也在launchApplication（）中实现。
public static void launchActivity(Context context, String deviceAddress){
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
mCurrentDeviceAddress = deviceAddress; //getIntent().getExtras().getString(ConnectionScreen.PREFS_DEVICE_ADDR);
mChatService = new BluetoothMeterService(context, mHandler);
connectDevice();
if (mChatService != null) {
if (mChatService.getState() == BluetoothMeterService.STATE_NONE) {
mChatService.start();
}
}
}
// Automatically try to connec with the known mac address;
private static class ConnectThread extends Thread {
private final BluetoothDevice device;
public ConnectThread(BluetoothDevice d) {
this.device = d;
}
public void run() {
while (mConnectThread == Thread.currentThread()) {
if (mChatService.getState() == BluetoothMeterService.STATE_CONNECTED) {
Log.e(TAG, "STATE_CONNECTED");
break;
} else if (mChatService.getState() == BluetoothMeterService.STATE_CONNECTING) {
try {
//Thread.sleep(2000);
Log.e(TAG, "STATE_CONNECTING");
mChatService.connect(device);
} catch (Exception e) {
// Log.e(TAG, e.getMessage());
}
} else
try {
Log.e(TAG, "STATE_DISCONECTED");
mChatService.start();
Thread.sleep(3000);
} catch (Exception e) {
// Log.e(TAG, e.getMessage());
Thread.currentThread().interrupt();
}
}
}
}
// create the bluetooth device object, and try to connect with it
// consistantly and automatically.
private static void connectDevice() {
if (mCurrentDeviceAddress == null) {
Toast.makeText(context, "Bluetooth MAC address is not assigned.",
Toast.LENGTH_SHORT).show();
//context.finish();
return;
}
BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(mCurrentDeviceAddress);
// showDialog(Dialog_Connect);
mConnectThread = new ConnectThread(device);
mConnectThread.start();
}
// The Handler that gets information back from the BluetoothMeterService
private static final Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
Log.e(TAG, msg.toString());
switch (msg.what) {
case MESSAGE_STATE_CHANGE:
switch (msg.arg1) {
case BluetoothMeterService.STATE_CONNECTED:
Log.e(TAG, "handler - STATE_CONNECTED");
for(CustomizedBluetoothDevice device : mDeviceList){
if(device.getAddress() == mCurrentDeviceAddress){
device.setStatus(BluetoothMeterService.STATE_CONNECTED);
}
}
updateUI(/*mDeviceList*/);
// mTextViewTitle.setText("Device: " + mConnectedDeviceName);
// mTextViewStatus.setText(R.string.title_connected_to);
break;
case BluetoothMeterService.STATE_CONNECTING:
Log.e(TAG, "handler - STATE_CONNECTING");
for(CustomizedBluetoothDevice device : mDeviceList){
if(device.getAddress() == mCurrentDeviceAddress){
device.setStatus(BluetoothMeterService.STATE_CONNECTING);
}
}
updateUI(/*mDeviceList*/);
// mTextViewStatus.setText(R.string.title_connecting);
break;
case BluetoothMeterService.STATE_NONE:
Log.e(TAG, "handler - STATE_NONE");
for(CustomizedBluetoothDevice device : mDeviceList){
if(device.getAddress() == mCurrentDeviceAddress){
device.setStatus(BluetoothMeterService.STATE_NONE);
}
}
updateUI(/*mDeviceList*/);
// mTextViewStatus.setText(R.string.title_not_connected);
break;
case BluetoothMeterService.STATE_DISCONNECTING:
Log.e(TAG, "handler - STATE_DISCONNECTING");
for(CustomizedBluetoothDevice device : mDeviceList){
if(device.getAddress() == mCurrentDeviceAddress){
device.setStatus(BluetoothMeterService.STATE_DISCONNECTING);
}
}
updateUI(/*mDeviceList*/);
break;
}
break;
case MESSAGE_WRITE:
break;
case MESSAGE_READ:
byte[] readBuf = (byte[]) msg.obj;
// construct a string from the valid bytes in the buffer
String readMessage = new String(readBuf, 0, msg.arg1);
Log.e(TAG, "handler - MESSAGE_READ " + readMessage);
// bufferMessege += readMessage;
/* if (mMessage != null) {
mMessage.add(new CustomizedMessage(readMessage, true));
updateUI();
}*/
// bufferMessege = "";
break;
case MESSAGE_DEVICE_NAME:
Log.e(TAG, "handler - MESSAGE_READ " + MESSAGE_DEVICE_NAME);
// save the connected device's name
mConnectedDeviceName = msg.getData().getString(DEVICE_NAME);
break;
case MESSAGE_TOAST:
Log.e(TAG, "handler - MESSAGE_READ " + MESSAGE_TOAST);
break;
}
}
};
public void stopActivity(){
if (mChatService != null)
{
mChatService.stop();
mChatService = null;
}
}
答案 0 :(得分：0)
我假设在您的一个活动的生命周期方法中调用了launchActivity。
如果是这样的话 - 你基本上是在创建一个附加的背景逻辑＆＃39;一个活动，即一个UI组件。 这是一个坏主意。
为什么？
因为Android在回收后台活动以及从中产生的线程时非常快，所以当资源不足时。
你应该做的是明确告知Android这个逻辑被视为背景逻辑，即 没有连接到屏幕上的活动可见性。
为此，您应该声明service。
在清单中：
<service
android:name="MyConnectionService"
android:icon="@drawable/icon"
android:label="@string/service_name" >
</service>
在代码中：
public class MyConnectionService extends Service {
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
// <------------ place connection logic here
}
@Override
public IBinder onBind(Intent intent) {
return null;
}
}
如果您希望逻辑与UI线程分开执行（我相信你会这样做），请使用IntentService
public class MyConnectionService extends IntentService {
@Override
protected void onHandleIntent(Intent intent) {
// <--------- run connection logic on a dedicated thread here
}
}
最后，如果您希望自己的服务始终保持无线状态（并且大多数应用不需要此类行为），请将您的服务声明为前台服务：
Notification notification = new Notification(R.drawable.icon, getText(R.string.msg_text),
System.currentTimeMillis());
Intent notificationIntent = new Intent(this, MyConnectionService.class);
PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0);
notification.setLatestEventInfo(this, getText(R.string.notification_title),
getText(R.string.notification_message), pendingIntent);
startForeground(SERVICE_NOTIFICATION_ID, notification);
答案 1 :(得分：0)
这实际上是正常的。到目前为止，您离开应用程序并且android生命周期调用onDestroy()方法，所有连接都应该脱机。因此，您需要一个在后台进一步工作的流程。您可以在此处使用Android Service组件。只要您使用资源，这将有效，只要它完成Service即将关闭的过程。所以这取决于你需要什么。如果您需要在后台永久运行的后台服务，则应使用startForeground()的{{1}}方法。
此处有关Service的更多信息：http://developer.android.com/guide/components/services.html