Android__Service

服务使程序实现后台运行，服务一般包含线程，线程依赖于应用进程，同理服务也是依赖
每一个创建该服务的应用进程，每一个打开的应用程序可以成为一个进程。
可成为一个进程，服务并不会自动开启线程，所有的代码都是默认在主线程里面运行的，
所以一般是在服务里面创建子线程，否则就可能出现主线程被阻塞的情况。

Android线程：
如果想进行UI操作，在子线程里是不能实现的，必须到主线程才能实现，一般在子线程
进行hanlder.sendMessage(message)—–然后在handler里进行逻辑操作

private Handler handler = new Handler(){    public void handleMessage(Message msg){        //逻辑操作    }};

线程信息的处理机制图：

Sevice(服务)：

服务的生命周期：onBind(),onCreate(),onStartCommand(),onDestroy()

public class MyService extends Service {    private DownLoadBinder mBinder = new DownLoadBinder();    //实现活动和服务的通信或者使联系更紧密    //创建一个实例，然后再onBind()里面返回一个实例，然后再MainActivity中    //新建ServiceConnection对象，在这对象里面重写两个方法，实现对mBlid    //实例的调用    class DownLoadBinder extends Binder{        public void startDownload(){            Log.d("MyService", "startDownload");        }        public int getProgress(){            Log.d("MyService", "getProgress");            return 0;        }    }    @Override    public IBinder onBind(Intent intent) {        // TODO Auto-generated method stub        return mBinder;    }    @Override    public void onCreate(){        super.onCreate();        //前台服务用法        Notification notification = new Notification(R.drawable.ic_launcher, "Notification",                 System.currentTimeMillis());        Intent notificationItent = new Intent(this,MainActivity.class);        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, notificationItent,0 );        notification.setLatestEventInfo(this, "This is Title", "This is content",pendingIntent );        //设置到通知栏显示一个前台服务        //这个时候的前台服务和通知有个很大的区别        //即服务不能一拉消除而通知可以        startForeground(1, notification);        Log.d("MyService", "onCreate executed");    }    @Override    public int onStartCommand(Intent intent,int flags,int startId){        Log.d("MyService", "onStartCommand executed");        return super.onStartCommand(intent, flags, startId);        //逻辑操作，在这里一般创建子线程    }    @Override    public void onDestroy(){        super.onDestroy();        Log.d("MyService", "onDestroy executed");    }}

public class MainActivity extends Activity implements OnClickListener{    private Button startService;    private Button stopService;    private Button startIntentService;    //实现活动和服务的联系即是绑定服务    private Button blind;    private Button Unblind;    //由于定义了一个内部类，所以要调用内部类的对象则    private MyService.DownLoadBinder downLoadBinder;    //然后还要通过一个ServiceConnection 实现对两个方法的调用    //serviceConnection,在绑定和解绑服务传入    private ServiceConnection serviceConnection = new ServiceConnection() {        @Override        public void onServiceDisconnected(ComponentName name) {            // TODO Auto-generated method stub//          Log.d("MyService", "unblinder OK");        }        @Override        public void onServiceConnected(ComponentName name, IBinder service) {            // TODO Auto-generated method stub            downLoadBinder = (MyService.DownLoadBinder)service;            downLoadBinder.startDownload();            downLoadBinder.getProgress();        }    };    @Override    protected void onCreate(Bundle savedInstanceState){        super.onCreate(savedInstanceState);        setContentView(R.layout.main_activity);        startIntentService = (Button)findViewById(R.id.intent_service_button);        startService = (Button)findViewById(R.id.start_service_button);        stopService = (Button)findViewById(R.id.stop_service_button);        blind = (Button)findViewById(R.id.bind_service_button);        Unblind = (Button)findViewById(R.id.ubind_service_button);        startService.setOnClickListener(this);        stopService.setOnClickListener(this);        blind.setOnClickListener(this);        Unblind.setOnClickListener(this);        startIntentService.setOnClickListener(this);    }    @Override    public void onClick(View v) {        // TODO Auto-generated method stub        switch(v.getId()){        case R.id.start_service_button:            Intent startIntent = new Intent(this,MyService.class);            //开启服务            startService(startIntent);            Toast.makeText(this, "开启服务", Toast.LENGTH_SHORT).show();            break;        case R.id.stop_service_button:            Intent stopIntent = new Intent(this,MyService.class);            stopService(stopIntent);            Toast.makeText(this, "关闭服务", Toast.LENGTH_SHORT).show();            break;        case R.id.bind_service_button:            Intent bindIntent = new Intent(this,MyService.class);            bindService(bindIntent, serviceConnection, BIND_AUTO_CREATE);            //绑定服务            break;        case R.id.ubind_service_button:            //解绑服务            unbindService(serviceConnection);            break;        case R.id.intent_service_button:            Log.d("MainActivity", "Thread id is "+Thread.currentThread().getId());            Intent intentService = new Intent(this,MyIntentService.class);            startService(intentService);            break;        default:            break;        }    }}

标准服务案例：
定时启动服务，实现定时操作

//AlarmManager对象    LongService extends Service{        onStartCommand(){            new Thread(new Runnable(){                @Override                public void run(){                }            }).start();        }    }

//这里是实现的是定时执行任务，只要把任务Log.d("LongRunningService", "executed at "+new Date().toString());替换就可以public class LongRunningService extends Service {    @Override    public IBinder onBind(Intent intent) {        // TODO Auto-generated method stub        return null;    }    @Override    public int onStartCommand(Intent intent, int flags, int startId){        new Thread(new Runnable() {            @Override            public void run() {                // TODO Auto-generated method stub                //执行任务                Log.d("LongRunningService", "executed at "+new Date().toString());            }        }).start();        //AlarmManager 对象        AlarmManager manager = (AlarmManager)getSystemService(ALARM_SERVICE);        int laytime = 6*1000;        long triggerAtTime = SystemClock.elapsedRealtime()+laytime;        Intent i = new Intent(this,AlarmReceiver.class);        PendingIntent pi = PendingIntent.getBroadcast(this, 0, i, 0);        //定时时间从系统开机开始，唤醒CPU        manager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP,triggerAtTime , pi);        //在这里的执行到广播接收器里面开启了新的服务，然后在广播接收器和LongRunningService不断循环不断执行任务        return super.onStartCommand(intent, flags, startId);    }}

public class AlarmReceiver extends BroadcastReceiver {    @Override    public void onReceive(Context context, Intent intent) {        // TODO Auto-generated method stub        Intent i = new Intent(context,LongRunningService.class);        context.startService(i);    }}

public class MainActivity extends Activity {    @Override    protected  void onCreate(Bundle savedInstanceState){        super.onCreate(savedInstanceState);        Intent i = new Intent(this,LongRunningService.class);        startService(i);    }}

//别忘了在<application>     <service android:name=".LongRunningService"></service>    <receiver android:name=".AlarmReceiver"></receiver></application>

分析： 首先从MainActivity开始启动        Intent i = new Intent(this,LongRunningService.class);        startService(i);        在LongRunningService.class启动了AlarmReceiver        在AlarmReceiver中又启动了LongRunningService.class        这样不断循坏开始