java - Android - 为什么此服务的多个实例正在运行

Question

我已经编写了一项服务，我计划让多个应用程序使用 Messenger 与其通信。我遵循了 Android Bound Services example for messenger 中的示例.我已将该服务放入一个 Android 库项目中，所有其他 Android 项目都使用该库。

我遇到的问题是，当我绑定(bind)到该服务时，它会运行多个服务实例。每个应用程序都以下列方式绑定(bind)到服务:

// Bind to the service
bindService(new Intent(ApplicationOneActivity.this, MessengerService.class), mConnection, Context.BIND_AUTO_CREATE);

服务是:

public class MessengerService extends Service {
    /** Command to the service to display a message */
    public static final int MSG_SAY_HELLO = 0;
    /** Command to the service to display a message from App 1 */
    public static final int MSG_APP1_HELLO = 1;

    public static final int MSG_APP2_HELLO = 2;

    public static final int MSG_APP3_HELLO = 3;

    private int[] stat = new int[3];

    private Timer timer = null;

    /**
     * Handler of incoming messages from clients.
     */
    class IncomingHandler extends Handler {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
            case MSG_SAY_HELLO:
                Toast.makeText(getApplicationContext(), "hello!", Toast.LENGTH_SHORT).show();
                break;
            case MSG_APP1_HELLO:
                Toast.makeText(getApplicationContext(), "App One says: " + msg.arg1, Toast.LENGTH_SHORT).show();
                stat[0] = msg.arg1;
                break;
            case MSG_APP2_HELLO:
                Toast.makeText(getApplicationContext(), "App Two says: " + msg.arg1, Toast.LENGTH_SHORT).show();
                stat[1] = msg.arg1;
                break;
            case MSG_APP3_HELLO:
                Toast.makeText(getApplicationContext(), "App Three says: " + msg.arg1, Toast.LENGTH_SHORT).show();
                stat[2] = msg.arg1;
                break;
            default:
                super.handleMessage(msg);
            }
        }
    }

    /**
     * Target we publish for clients to send messages to IncomingHandler.
     */
    final Messenger mMessenger = new Messenger(new IncomingHandler());

    /**
     * When binding to the service, we return an interface to our messenger
     * for sending messages to the service.
     */
    @Override
    public IBinder onBind(Intent intent) {
        Toast.makeText(getApplicationContext(), "binding", Toast.LENGTH_SHORT).show();

        return mMessenger.getBinder();

    }

    @Override
    public boolean onUnbind(Intent intent) {
        Toast.makeText(getApplicationContext(), "unbinding", Toast.LENGTH_SHORT).show();
        return super.onUnbind(intent);
    }

    final Handler handler = new Handler() {

        public void handleMessage(Message msg) {
            // Create and send a message to the service, using a supported 'what' value
            ReportAsyncTask report = new ReportAsyncTask();
            report.execute("");
        }
    };


    @Override
    public void onCreate() {
        super.onCreate();

        if (timer == null) {
            timer = new Timer();
            timer.schedule(new ScheduledTaskWithHandeler(), 10000);
            Toast.makeText(getApplicationContext(), "Register Timer To Report Back ", Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if (timer != null) {
            timer.cancel();
            timer = null;
        }
    }

    class ScheduledTaskWithHandeler extends TimerTask {

        @Override
        public void run() {
            handler.sendEmptyMessage(0);
        }
    }

    private class ReportAsyncTask extends AsyncTask<String, Void, String> {
        @Override
        protected String doInBackground(String... urls) {
            String response = "";
            try {
                String urlParams="device=" + URLEncoder.encode(android.os.Build.MODEL, "UTF-8")
                        + "&status="+URLEncoder.encode("App1 says " + stat[0] + ", App2 says " + stat[1] + ", App3 says " + stat[2],"UTF-8");
                String url = "http://192.168.43.143:8080/SimpleServlet3/monitor-servlet";
                HttpClient httpclient = new DefaultHttpClient();
                HttpGet httpget = new HttpGet(url+"?"+urlParams);
                HttpResponse httpresponse = httpclient.execute(httpget);
                HttpEntity entity = httpresponse.getEntity();
                if (entity != null) {
                    InputStream instream = entity.getContent();
                    int l;
                    byte[] tmp = new byte[2048];
                    while ((l = instream.read(tmp)) != -1) {
                        response += l;
                    }
                }
                timer.schedule(new ScheduledTaskWithHandeler(), 10000);
            } catch (Exception e) {
                e.printStackTrace();
            }
            return response;
        }

        @Override
        protected void onPostExecute(String result) {
            Toast.makeText(getApplicationContext(), "Server says " + result, Toast.LENGTH_SHORT).show();
        }

    }

}

每个应用程序的 list 看起来更像是:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.app1"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="11" />

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />

    <application
        android:icon="@drawable/spinifex"
        android:label="@string/app_name" >
        <activity
            android:name=".ApplicationOneActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <service
            android:name="com.example.services.MessengerService"
            android:process=":remote" />
    </application>

</manifest>

知道我做错了什么吗？ Toast 消息非常明确地表明同一服务的多个实例正在运行。我的项目结构错了吗？我不应该把服务放在一个单独的图书馆项目中吗？

Answer 1

您必须声明 <service />仅在一个 AndroidManifest 中标记，而在其他应用中，您必须通过完整的组件名称进行绑定(bind)。如:

Intent intent = new Intent();
intent.setClassName(
  "com.example.app1" /* your package which contains service */,
  "com.example.services.MessengerService" /* service name */
);

bindService(intent, mConnection, Context.BIND_AUTO_CREATE);

另外，当你做 android:process=":remote" ，您告诉 android 该进程对当前应用程序是私有(private)的。