我写了两个应用程序（目标姜饼）。让我们说app1和app2。 App1有两个以“BOOT_COMPLETED”开头的服务，它们以返回值START_STICKY开头。它们在不同的线程中运行。使长话短说。其中一项服务是监视串行端口上的传入数据（一种代理，用于与串行端口另一端的接口通信的应用程序）。另一个让听众观看一些系统状态并等待来自其他应用程序的一些“指令”。我知道它们运行良好，因为它们列在正在运行的服务中，并且我添加了一些代码，当某些特定数据来自串行端口时，它会强制它们执行某些操作。
现在问题：我写了app2。它尝试绑定到app1中的某个服务。我使用了android-developper文档，并在app1和app2中的服务之间实现了双向通信。由于我只需要发送少量非常简单的数据，因此我建议使用信使。我基本上只使用“what，arg1和arg2”我没有使用AIDL接口，因为文档建议。
这是androidmanifest在app1中声明服务的部分我也尝试绑定。
<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>
然后，以下是在app1中处理此问题的几种方法：
@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;
}
对于app2，这是与双向通信建立绑定的相关代码：
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.");
}
}
查看正在运行的服务，我可以看到我在app2中创建的服务正在运行。 Logcat向我显示我尝试绑定ModemWatcherService但找不到它。这是logcat的有趣部分
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
我的第一个想法是我错过了一个权限但是bindService（）可以抛出安全异常，在这种情况下它并非如此，我检查了它并且由于未知原因返回false。此外，我知道在app1中，onBind永远不会被称为证明绑定从未发生过。所以logcat消息“not found”有意义，但我在其清单中声明了service public。这可能是一个简单的错误，但我已经在这个问题已经有一段时间了，我找不到原因。知道为什么app2无法在app1中找到服务吗？我只使用剪切和粘贴名称，所以我不会做名字中的愚蠢错误拼写错误。我是否缺少某种权限？我是否需要做一些额外的步骤来发布整个系统的服务？这是我第一次尝试从另一个应用程序访问一个应用程序中的内容，所以我可能错过了一些东西。
答案 0 :(得分：20)
您的ComponentName构造错误。传入类名时必须完全限定，如下所示：
intentForMcuService.setComponent(new ComponentName("com.admetric.modemwatcher",
"com.admetric.modemwatcher.ModemWatcherService"));
另外，如果您在应用程序的边界之外引用Service，最好不要使用ComponentName来引用它，即使它确实可以正常工作。更常见的方法是为Intent创建自定义ACTION字符串，并使Service过滤该行动。