2011.07.13——— android remote service bind

2011.07.13——— android remote service bind

参考：http://blog.csdn.net/saintswordsman/article/details/5130947
http://www.imobilebbs.com/wordpress/?p=1265

Android Interface Definition Language（AIDL）和其它一些支持远程方法调用RMI的系统的IDL类似，它定义了Service和Client 之间的使用接口约定，这种远程调用一般需要通过进程间通信机制(IPC)来实现。在Android系统，一个进程（Process)通常不能直接访问其它进程的内存空间，Android系统支持使用AIDL来实现使用不同进程间调用服务接口

AIDL接口定义使用Java Interface语法定义在 .aidl文件中，然后必须同时放在Service和Client 的 src目录下。 当使用Eclipse 编译时，Android SDK工具会根据 .aidl的接口定义自动生成对应的IBinder接口定义 （定义在gen目录下） Service必须实现由这个IBinder接口定义。 Client然后可以通过绑定Service来访问这些方法。

1. 创建. aidl 文件
本例有两个

IRemoteService

package com.example.android.apis.app;

import com.example.android.apis.app.IRemoteServiceCallback;

/**
 * Example of defining an interface for calling on to a remote service
 * (running in another process).
 */
interface IRemoteService {
   
    void registerCallback(IRemoteServiceCallback cb);
    
    /**
     * Remove a previously registered callback interface.
     */
    void unregisterCallback(IRemoteServiceCallback cb);
}

IRemoteServiceCallback

package com.example.android.apis.app;

oneway interface IRemoteServiceCallback {
    /**
     * Called when the service has a new value for you.
     */
    void valueChanged(int value);
}

2. service

public class RemoteService extends Service {
    /**
     * This is a list of callbacks that have been registered with the
     * service.  Note that this is package scoped (instead of private) so
     * that it can be accessed more efficiently from inner classes.
     */
    final RemoteCallbackList<IRemoteServiceCallback> mCallbacks
            = new RemoteCallbackList<IRemoteServiceCallback>();
    
    int mValue = 0;
    NotificationManager mNM;
    
    @Override
    public void onCreate() {
        mNM = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);

        // Display a notification about us starting.
        showNotification();
        
        // While this service is running, it will continually increment a
        // number.  Send the first message that is used to perform the
        // increment.
        System.out.println("create start");
        mHandler.sendEmptyMessage(REPORT_MSG);
        System.out.println("create end");
    }

    @Override
    public void onDestroy() {
        // Cancel the persistent notification.
        mNM.cancel(R.string.remote_service_started);

        // Tell the user we stopped.
        Toast.makeText(this, R.string.remote_service_stopped, Toast.LENGTH_SHORT).show();
        
        // Unregister all callbacks.
        mCallbacks.kill();
        
        // Remove the next pending message to increment the counter, stopping
        // the increment loop.
        mHandler.removeMessages(REPORT_MSG);
    }
    

    @Override
    public IBinder onBind(Intent intent) {
        // Select the interface to return.  If your service only implements
        // a single interface, you can just return it here without checking
        // the Intent.
        System.out.println("bind");
        if (IRemoteService.class.getName().equals(intent.getAction())) {
            return mBinder;
        }
        if (ISecondary.class.getName().equals(intent.getAction())) {
            return mSecondaryBinder;
        }
        return null;
    }

    /**
     * The IRemoteInterface is defined through IDL
     */
    private final IRemoteService.Stub mBinder = new IRemoteService.Stub() {
        public void registerCallback(IRemoteServiceCallback cb) {
            if (cb != null) mCallbacks.register(cb);
        }
        public void unregisterCallback(IRemoteServiceCallback cb) {
            if (cb != null) mCallbacks.unregister(cb);
        }
    };

    
    private static final int REPORT_MSG = 1;
    
    /**
     * Our Handler used to execute operations on the main thread.  This is used
     * to schedule increments of our value.
     */
    private final Handler mHandler = new Handler() {
        @Override public void handleMessage(Message msg) {
            switch (msg.what) {
                
                // It is time to bump the value!
                case REPORT_MSG: {
                    // Up it goes.
                    int value = ++mValue;
                    
                    // Broadcast to all clients the new value.
                    final int N = mCallbacks.beginBroadcast();
                    System.out.println("handler "+N);
                    for (int i=0; i<N; i++) {
                        try {
                            mCallbacks.getBroadcastItem(i).valueChanged(value);
                        } catch (RemoteException e) {
                            // The RemoteCallbackList will take care of removing
                            // the dead object for us.
                        }
                    }
                    mCallbacks.finishBroadcast();
                    
                    // Repeat every 1 second.
                    sendMessageDelayed(obtainMessage(REPORT_MSG), 1*1000);
                } break;
                default:
                    super.handleMessage(msg);
            }
        }
    };

    /**
     * Show a notification while this service is running.
     */
    private void showNotification() {
        // In this sample, we'll use the same text for the ticker and the expanded notification
        CharSequence text = getText(R.string.remote_service_started);

        // Set the icon, scrolling text and timestamp
        Notification notification = new Notification(R.drawable.stat_sample, text,
                System.currentTimeMillis());

        // The PendingIntent to launch our activity if the user selects this notification
        PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                new Intent(this, Controller.class), 0);

        // Set the info for the views that show in the notification panel.
        notification.setLatestEventInfo(this, getText(R.string.remote_service_label),
                       text, contentIntent);

        // Send the notification.
        // We use a string id because it is a unique number.  We use it later to cancel.
        mNM.notify(R.string.remote_service_started, notification);
    }

3、activity端

public static class Binding extends Activity {
        /** The primary interface we will be calling on the service. */
        IRemoteService mService = null;
        /** Another interface we use on the service. */
        ISecondary mSecondaryService = null;
        
        Button mKillButton;
        TextView mCallbackText;

        private boolean mIsBound;

        /**
         * Standard initialization of this activity.  Set up the UI, then wait
         * for the user to poke it before doing anything.
         */
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            setContentView(R.layout.remote_service_binding);

            // Watch for button clicks.
            Button button = (Button)findViewById(R.id.bind);
            button.setOnClickListener(mBindListener);
            button = (Button)findViewById(R.id.unbind);
            button.setOnClickListener(mUnbindListener);
            mKillButton = (Button)findViewById(R.id.kill);
            mKillButton.setOnClickListener(mKillListener);
            mKillButton.setEnabled(false);
            
            mCallbackText = (TextView)findViewById(R.id.callback);
            mCallbackText.setText("Not attached.");
        }

        /**
         * Class for interacting with the main interface of the service.
         */
        private ServiceConnection mConnection = new ServiceConnection() {
            public void onServiceConnected(ComponentName className,
                    IBinder service) {
                mService = IRemoteService.Stub.asInterface(service);
                mKillButton.setEnabled(true);
                mCallbackText.setText("Attached.");

                // We want to monitor the service for as long as we are
                // connected to it.
                try {
                    mService.registerCallback(mCallback);
                } catch (RemoteException e) {
                }
                
                // As part of the sample, tell the user what happened.
                Toast.makeText(Binding.this, R.string.remote_service_connected,
                        Toast.LENGTH_SHORT).show();
            }

            public void onServiceDisconnected(ComponentName className) {
                // This is called when the connection with the service has been
                // unexpectedly disconnected -- that is, its process crashed.
                mService = null;
                mKillButton.setEnabled(false);
                mCallbackText.setText("Disconnected.");

                // As part of the sample, tell the user what happened.
                Toast.makeText(Binding.this, R.string.remote_service_disconnected,
                        Toast.LENGTH_SHORT).show();
            }
        };

        private OnClickListener mBindListener = new OnClickListener() {
            public void onClick(View v) {
                bindService(new Intent(IRemoteService.class.getName()),
                        mConnection, Context.BIND_AUTO_CREATE);
                bindService(new Intent(ISecondary.class.getName()),
                        mSecondaryConnection, Context.BIND_AUTO_CREATE);
                mIsBound = true;
                mCallbackText.setText("Binding.");
            }
        };

        private OnClickListener mUnbindListener = new OnClickListener() {
            public void onClick(View v) {
                if (mIsBound) {
                    // If we have received the service, and hence registered with
                    // it, then now is the time to unregister.
                    if (mService != null) {
                        try {
                            mService.unregisterCallback(mCallback);
                        } catch (RemoteException e) {
                            // There is nothing special we need to do if the service
                            // has crashed.
                        }
                    }
                    
                    // Detach our existing connection.
                    unbindService(mConnection);
                    unbindService(mSecondaryConnection);
                    mKillButton.setEnabled(false);
                    mIsBound = false;
                    mCallbackText.setText("Unbinding.");
                }
            }
        };

        private OnClickListener mKillListener = new OnClickListener() {
            public void onClick(View v) {
                // To kill the process hosting our service, we need to know its
                // PID.  Conveniently our service has a call that will return
                // to us that information.
                if (mSecondaryService != null) {
                    try {
                        int pid = mSecondaryService.getPid();
                        Process.killProcess(pid);
                        mCallbackText.setText("Killed service process.");
                    } catch (RemoteException ex) {
                        // Recover gracefully from the process hosting the
                        // server dying.
                        // Just for purposes of the sample, put up a notification.
                        Toast.makeText(Binding.this,
                                R.string.remote_call_failed,
                                Toast.LENGTH_SHORT).show();
                    }
                }
            }
        };
        
        // ----------------------------------------------------------------------
        // Code showing how to deal with callbacks.
        // ----------------------------------------------------------------------
        
        /**
         * This implementation is used to receive callbacks from the remote
         * service.
         */
        private IRemoteServiceCallback mCallback = new IRemoteServiceCallback.Stub() {
            public void valueChanged(int value) {
                mHandler.sendMessage(mHandler.obtainMessage(BUMP_MSG, value, 0));
            }
        };
        
        private static final int BUMP_MSG = 1;
        
        private Handler mHandler = new Handler() {
            @Override public void handleMessage(Message msg) {
                switch (msg.what) {
                    case BUMP_MSG:
                        mCallbackText.setText("Received from service: " + msg.arg1);
                        break;
                    default:
                        super.handleMessage(msg);
                }
            }
            
        };
    }

大致流程图：