绑定到服务，从另一个应用程序 [英] Binding to a service from another app
问题描述
我写了两个应用程序（目标姜饼）。让说APP1 APP2和。 APP1已经开始与BOOT_COMPLETED两个服务，他们都开始与返回值START_STICKY。他们在单独的线程中运行。为了使长话短说。其中的服务都在注视着一个串行端口（一种为代理程序上的串行端口，另一端接口通信）的输入数据。另外有一个听众看一些系统状态，并等待来自其他应用程序的一些指令。我知道他们均运行良好，因为它们在运行的服务列出，我添加了一些code，迫使他们做一些东西时，一些特定的数据来自串口。
I wrote two apps (target Gingerbread). Let say app1 and app2. App1 has two services started with "BOOT_COMPLETED" and they are started with the return value START_STICKY. They run in separate threads. To make a long story short. One of the service is watching for incoming data on a serial port (a kind of proxy for app communicating with interfaces on the other end of the serial port). The other has a listener watching some system status and waiting for some "instructions" from other apps. I know they are running well because they are listed in the running services and I added some code that forces them to do some stuff when some specific data come from the serial port.
现在的问题：我写了APP2。它试图绑定到APP1服务之一。我用 Android的developper 文档和实施了APP1和APP2服务之间的双向通信。因为我只是有少量的非常简单的数据的发送，我用了一个使者，为建议。我基本上只用是什么，ARG1 ARG2和我没有使用AIDL接口的文档是在暗示。
Now the problem: I wrote app2. It tries to bind to one of the service in app1. I used android-developper documentation and implemented a bidirectional communication between the service in app1 and app2. Since I just have a small amount of very simple data to send, I used a messenger, as suggested. I basically just use the "what, arg1 and arg2" I did not use the AIDL interface as the documentation was suggesting.
下面是androidmanifest声明服务APP1我尝试绑定过的部分。
Here is the section of the androidmanifest declaring the service in app1 I try to bind too.
<service android:name=".ModemWatcherService"
android:label="@string/app_name"
android:exported="true">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
<!-- Service name -->
<action android:name="com.admetric.modemwatcher.Service" />
</intent-filter>
</service>
那么，这里是处理在APP1这个问题上的一些方法：
Then, here are the few method dealing with this issue in app1:
@Override
public IBinder onBind(Intent intent) {
Log.d(TAG, "entering onBind");
return mMessenger.getBinder();
}
/**
* Handler of incoming messages from clients.
*/
class IncomingHandler extends Handler {
@Override
public void handleMessage(Message msg) {
String logMessage = "Received meaasge what= %d, arg1= %d, arg2= %d" + String.valueOf(msg.what) + String.valueOf(msg.arg1) + String.valueOf( msg.arg2);
Log.d(TAG, logMessage);
switch (msg.what) {
case MSG_REGISTER_CLIENT:
mClients.add(msg.replyTo);
break;
case MSG_UNREGISTER_CLIENT:
mClients.remove(msg.replyTo);
break;
case .....
more code here for the application
default:
super.handleMessage(msg);
}
}
}
@Override
public void onCreate() {
mHandler = new Handler();
startSignalLevelListener();
Log.i(TAG, "Just did onCreated");
// Display a notification about us starting. We put an icon in the status bar.
// showNotification();
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.i(TAG, "Received start id " + startId + ": " + intent);
// We want this service to continue running until it is explicitly
// stopped, so return sticky.
return START_STICKY;
}
有关APP2，这里是有关code建立与双向通信的绑定：
For app2, here is the relevant code to establish the binding with the bidirectional communication:
public final class ComWithIoMcu extends Service {
private static final String TAG = "ComWithIoMcu";
/** Messenger for communicating with service. */
static Messenger mServiceMcu = null;
/** Flag indicating whether we have called bind on the service. */
boolean mIsBound;
/**
* Command to the service to register a client, receiving callbacks
* from the service. The Message's replyTo field must be a Messenger of
* the client where callbacks should be sent.
*/
static final int MSG_REGISTER_CLIENT = 1;
/**
* Command to the service to unregister a client, ot stop receiving callbacks
* from the service. The Message's replyTo field must be a Messenger of
* the client as previously given with MSG_REGISTER_CLIENT.
*/
static final int MSG_UNREGISTER_CLIENT = 2;
/**
* Command to forward a string command to the I/O MCU
*/
public static final int MSG_SEND_STRING_TO_IOMCU = 3;
/** List of supported commands
*
*/
...... more code ....
/**
* Handler of incoming messages from service.
*/
class IncomingHandler extends Handler {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_UNSOL_MESSAGE:
Log.d(TAG, "Received from service: " + msg.arg1);
break;
default:
super.handleMessage(msg);
}
}
}
/**
* Target we publish for clients to send messages to IncomingHandler.
*/
final Messenger mMessenger = new Messenger(new IncomingHandler());
boolean mBound;
/**
* Class for interacting with the main interface of the service.
*/
private ServiceConnection mConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className,
IBinder service) {
// This is called when the connection with the service has been
// established, giving us the service object we can use to
// interact with the service. We are communicating with our
// service through an IDL interface, so get a client-side
// representation of that from the raw service object.
mServiceMcu = new Messenger(service);
Log.d(TAG, "Attached.");
// We want to monitor the service for as long as we are
// connected to it.
try {
Message msg = Message.obtain(null,
MSG_REGISTER_CLIENT);
msg.replyTo = mMessenger;
mServiceMcu.send(msg);
} catch (RemoteException e) {
// In this case the service has crashed before we could even
// do anything with it; we can count on soon being
// disconnected (and then reconnected if it can be restarted)
// so there is no need to do anything here.
Log.e(TAG, "ModemWatcherService is not running");
}
}
public void onServiceDisconnected(ComponentName className) {
// This is called when the connection with the service has been
// unexpectedly disconnected -- that is, its process crashed.
mServiceMcu = null;
mBound = false;
}
};
void doBindService() {
// Establish a connection with the service. We use an explicit
// class name because there is no reason to be able to let other
// applications replace our component.
//bindService(new Intent(this, MessengerService.class), mConnection, Context.BIND_AUTO_CREATE);
try {
Intent intentForMcuService = new Intent();
Log.d(TAG, "Before init intent.componentName");
intentForMcuService.setComponent(new ComponentName("com.admetric.modemwatcher", "ModemWatcherService"));
Log.d(TAG, "Before bindService");
if (bindService(intentForMcuService, mConnection, 0)){
Log.d(TAG, "Binding to Modem Watcher returned true");
} else {
Log.d(TAG, "Binding to Modem Watcher returned false");
}
} catch (SecurityException e) {
Log.e(TAG, "can't bind to ModemWatcherService, check permission in Manifest");
}
mIsBound = true;
Log.d(TAG, "Binding.");
}
void doUnbindService() {
if (mIsBound) {
// If we have received the service, and hence registered with
// it, then now is the time to unregister.
if (mServiceMcu != null) {
try {
Message msg = Message.obtain(null, MSG_UNREGISTER_CLIENT);
msg.replyTo = mMessenger;
mServiceMcu.send(msg);
} catch (RemoteException e) {
// There is nothing special we need to do if the service
// has crashed.
}
}
// Detach our existing connection.
unbindService(mConnection);
mIsBound = false;
Log.d(TAG, "Unbinding.");
}
}
看着正在运行的服务，我可以看到我在APP2创建的服务正在运行。 logcat的向我表明我尝试绑定的ModemWatcherService，但没有找到。这里是logcat中有趣的部分。
Looking at the running services, I can see that the service I created in app2 is running. Logcat shows me that I try to bind the the ModemWatcherService but it is not found. Here is the interesting section of logcat
12-05 17:22:59.884 D/ComWithIoMcu( 547): Before init intent.componentName
12-05 17:22:59.884 D/ComWithIoMcu( 547): Before bindService
12-05 17:22:59.888 D/ComWithIoMcu( 547): Binding to Modem Watcher returned false
12-05 17:22:59.888 D/ComWithIoMcu( 547): Binding.
12-05 17:22:59.888 W/ActivityManager( 89): Unable to start service Intent { cmp=com.admetric.modemwatcher/ModemWatcherService }: not found
我首先想到的是，我是缺少一个权限，但bindService（）可以特罗安全异常，在这种情况下，它不会这样，我检查，因为某种未知原因返回false。另外，我知道，在APP1的onBind不会被调用证明的结合从未发生过。所以logcat的消息没有发现意义，但我宣布，服务公众在其清单。这可能是一个简单的错误，但我一直在这个ISSU有一段时间了，我也没找到原因。任何想法，为什么APP2找不到APP1服务？我只使用了剪切和粘贴的名字，所以我不会在名字做愚蠢的错误输入错误。我缺少某种权限？我需要做一些额外的步骤，将服务发布为整个系统？这是我第一次尝试从另一个应用程序，所以，我可能会错过一些东西访问一个应用程序。
My first thought was that I was missing a permission but bindService() can trow security exceptions and in this case it doesn't so, I checked and it returns false for an unknown reason. Also, I know that in app1, the onBind is never called proving that the binding never occurred. So the logcat message "not found" make sense but I declared that service public in its manifest. It's probably a simple mistake but I've been on this issu for a while now and I did not find why. Any idea why app2 can't find the service in app1 ? I used just cut and paste for names so I would not do stupid mistyping mistakes in names. Am I missing permissions of some sort? Do I need to do some extra step to publish the service for the whole system? That's the first time I try to access something in one app from another app so, I might have missed something.
推荐答案
您组件名错误地构造。当传递类名必须是完全限定像这样：
Your ComponentName is incorrectly constructed. When passing in the class name is must be fully qualified like so:
intentForMcuService.setComponent(new ComponentName("com.admetric.modemwatcher",
"com.admetric.modemwatcher.ModemWatcherService"));
另一件事，如果你引用一个服务应用程序的边界之外，它可能是最好不要使用组件名来引用它，即使它正常工作。更常见的方法是创建一个自定义操作字符串的意图并具有服务过滤动作。
Another thing, if you are referencing a Service outside the boundaries of the application, it's probably best not to use ComponentName to reference it, even if it does work correctly. A more common approach would be to create a custom ACTION string for your Intent and have the Service filter that action.
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