Android example source code file (RemoteService.java)

This example Android source code file (RemoteService.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

activity, android, app, application, binding, bump_msg, button, content, handler, ibinder, intent, notificationmanager, onclicklistener, os, override, remotecallbacklist, remoteexception, report_msg, serviceconnection, ui

The RemoteService.java Android example source code

/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.android.apis.app;

import android.app.Activity;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.RemoteException;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.os.Process;
import android.os.RemoteCallbackList;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

// Need the following import to get access to the app resources, since this
// class is in a sub-package.
import com.example.android.apis.R;

/**
 * This is an example of implementing an application service that runs in a
 * different process than the application.  Because it can be in another
 * process, we must use IPC to interact with it.  The
 * {@link Controller} and {@link Binding} classes
 * show how to interact with the service.
 * 
 * <p>Note that most applications do not need to deal with
 * the complexity shown here.  If your application simply has a service
 * running in its own process, the {@link LocalService} sample shows a much
 * simpler way to interact with it.
 */
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.
        mHandler.sendEmptyMessage(REPORT_MSG);
    }

    @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.
        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);
        }
    };

    /**
     * A secondary interface to the service.
     */
    private final ISecondary.Stub mSecondaryBinder = new ISecondary.Stub() {
        public int getPid() {
            return Process.myPid();
        }
        public void basicTypes(int anInt, long aLong, boolean aBoolean,
                float aFloat, double aDouble, String aString) {
        }
    };

    
    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();
                    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);
    }
    
    // ----------------------------------------------------------------------
    
    /**
     * <p>Example of explicitly starting and stopping the remove service.
     * This demonstrates the implementation of a service that runs in a different
     * process than the rest of the application, which is explicitly started and stopped
     * as desired.</p>
     * 
     * <p>Note that this is implemented as an inner class only keep the sample
     * all together; typically this code would appear in some separate class.
     */
    public static class Controller extends Activity {
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            setContentView(R.layout.remote_service_controller);

            // Watch for button clicks.
            Button button = (Button)findViewById(R.id.start);
            button.setOnClickListener(mStartListener);
            button = (Button)findViewById(R.id.stop);
            button.setOnClickListener(mStopListener);
        }

        private OnClickListener mStartListener = new OnClickListener() {
            public void onClick(View v) {
                // Make sure the service is started.  It will continue running
                // until someone calls stopService().
                // We use an action code here, instead of explictly supplying
                // the component name, so that other packages can replace
                // the service.
                startService(new Intent(
                        "com.example.android.apis.app.REMOTE_SERVICE"));
            }
        };

        private OnClickListener mStopListener = new OnClickListener() {
            public void onClick(View v) {
                // Cancel a previous call to startService().  Note that the
                // service will not actually stop at this point if there are
                // still bound clients.
                stopService(new Intent(
                        "com.example.android.apis.app.REMOTE_SERVICE"));
            }
        };
    }
    
    // ----------------------------------------------------------------------
    
    /**
     * Example of binding and unbinding to the remote service.
     * This demonstrates the implementation of a service which the client will
     * bind to, interacting with it through an aidl interface.</p>
     * 
     * <p>Note that this is implemented as an inner class only keep the sample
     * all together; typically this code would appear in some separate class.
     */

    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) {
                // 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.
                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) {
                    // 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.
                }
                
                // 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();
            }
        };

        /**
         * Class for interacting with the secondary interface of the service.
         */
        private ServiceConnection mSecondaryConnection = new ServiceConnection() {
            public void onServiceConnected(ComponentName className,
                    IBinder service) {
                // Connecting to a secondary interface is the same as any
                // other interface.
                mSecondaryService = ISecondary.Stub.asInterface(service);
                mKillButton.setEnabled(true);
            }

            public void onServiceDisconnected(ComponentName className) {
                mSecondaryService = null;
                mKillButton.setEnabled(false);
            }
        };

        private OnClickListener mBindListener = new OnClickListener() {
            public void onClick(View v) {
                // Establish a couple connections with the service, binding
                // by interface names.  This allows other applications to be
                // installed that replace the remote service by implementing
                // the same interface.
                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();
                        // Note that, though this API allows us to request to
                        // kill any process based on its PID, the kernel will
                        // still impose standard restrictions on which PIDs you
                        // are actually able to kill.  Typically this means only
                        // the process running your application and any additional
                        // processes created by that app as shown here; packages
                        // sharing a common UID will also be able to kill each
                        // other's processes.
                        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() {
            /**
             * This is called by the remote service regularly to tell us about
             * new values.  Note that IPC calls are dispatched through a thread
             * pool running in each process, so the code executing here will
             * NOT be running in our main thread like most other things -- so,
             * to update the UI, we need to use a Handler to hop over there.
             */
            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);
                }
            }
            
        };
    }

}