程序的重要性優先順序：1. 前臺程序：Foreground process使用者正在互動的Activity（onResume()當某個Service繫結正在互動的Activity被主動呼叫為前臺的Service(startForeground())元件正在執行生命週期的回撥（(onCreate() /onStart()/onDestory())BroadcastReceiver 正在執行onReceive()；2.可見程序：Visible process我們的Activity處在onPause() (沒有進入onStop())繫結到前臺Activity的Service3.服務程序：Service process簡單的startservice()啟動4.後臺程序：Background process對使用者沒有直接影響的程序-----Activity處於onStop()的時候5.空程序 ：Empty process不含有任何的活動的元件。(android設計的，為了第二次啟動更快，採取了一個權衡)程序越往後越容易被系統殺死

如何不被系統殺死

我們要如何提升程序的優先順序(儘量做到不輕易被系統殺死)，提供以下七個方案1. 模仿QQ採取在鎖屏的時候啟動1個畫素的Activity。

背景：當手機鎖屏的時候什麼都乾死了，為了省電。

監聽鎖屏廣播，鎖了---啟動這個1畫素Activity。

監聽鎖屏的， 開啟---結束掉這個1畫素Activity。

要監聽鎖屏的廣播---動態註冊。

關鍵程式碼：

 public class KeepLiveActivityManager {  private static KeepLiveActivityManager instance;  private Context context;  private WeakReference<Activity> activityInstance;  public static KeepLiveActivityManager getInstance(Context context) {    if(instance==null){      instance = new KeepLiveActivityManager(context.getApplicationContext());    }    return instance;  }  private KeepLiveActivityManager(Context context) {    this.context = context;  }  public void setKeepLiveActivity(Activity activity){    activityInstance = new WeakReference<Activity>(activity);  }  public void startKeepLiveActivity() {    Intent intent = new Intent(context, KeepLiveActivity.class);    intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);    context.startActivity(intent);  }  public void finishKeepLiveActivity() {    if(activityInstance!=null&&activityInstance.get()!=null){      Activity activity = activityInstance.get();      activity.finish();    }  }}

原始碼地址：https://github.com/kpioneer123/KeepLiveProcess2. 大型App運營商和手機廠商可能有合作關係---白名單3. 雙程序守護

一個程序被殺死，另外一個程序又被他啟動，相互監聽啟動。

A<---->B殺程序是一個一個殺的，本質是和殺程序時間賽跑。關鍵程式碼：

 public class LocalService extends Service {  public static final String ACTION_LOCAL_SERVICE = "com.haocai.app.keepliveprocess.LocalService";  private static final String TAG = "LocalService";  private MyServiceConnection conn;  private MyBinder binder;  private Intent testIntent;  @Override  public void onCreate() {    // TODO Auto-generated method stub    super.onCreate();    if(binder ==null){      binder = new MyBinder();    }    conn = new MyServiceConnection();  }  @Nullable  @Override  public IBinder onBind(Intent intent) {    return binder;  }  @Override  public void onDestroy() {    super.onDestroy();    if(testIntent!=null){      stopService(testIntent);    }    //unbindService(conn);  }  //啟動前臺程序 增加重要性優先順序  @Override  public int onStartCommand(Intent intent, int flags, int startId) {    LocalService.this.bindService(new Intent(LocalService.this, RemoteService.class),                                       conn, Context.BIND_IMPORTANT);    PendingIntent contentIntent = PendingIntent.getService(this, 0, intent, 0);    NotificationCompat.Builder builder = new NotificationCompat.Builder(this);    builder.setTicker("360")        .setContentIntent(contentIntent)        .setContentTitle("我是360，我怕誰!")        .setAutoCancel(true)        .setContentText("hehehe")        .setWhen( System.currentTimeMillis());    //把service設定為前臺執行，避免手機系統自動殺掉改服務。    startForeground(startId, builder.build());    return START_STICKY;  }  class MyBinder extends RemoteConnection.Stub{    @Override    public String getProcessName() throws RemoteException {      // TODO Auto-generated method stub      return "LocalService";    }  }  class MyServiceConnection implements ServiceConnection {    @Override    public void onServiceConnected(ComponentName name, IBinder service) {      Log.i(TAG, "建立連線成功！");    }    @Override    public void onServiceDisconnected(ComponentName name) {      Log.i(TAG, "本地服務被幹掉了~~~~~斷開連線!");      Toast.makeText(LocalService.this, "斷開連線", Toast.LENGTH_SHORT).show();      //啟動被幹掉的      testIntent = new Intent();      //自定義的Service的action      testIntent.setAction(RemoteService.ACTION_REMOTE_SERVICE);      //自定義Service的包名      testIntent.setPackage(getPackageName());      Log.i("999", getPackageName() + "");      startService(testIntent);      LocalService.this.bindService(new Intent(LocalService.this, RemoteService.class), conn,                                          Context.BIND_IMPORTANT);    }  }  }

原始碼地址：https://github.com/kpioneer123/KeepLiveProcess24. JobScheduler

把任務加到系統排程佇列中，當到達任務視窗期的時候就會執行，我們可以在這個任務裡面啟動我們的程序。這樣可以做到將近殺不死的程序。

@SuppressLint("NewApi")public class JobHandleService extends JobService{  public static final String ACTION_JOB_HANDLE_SERVICE =       "com.haocai.app.keepliveprocess.JobHandleService";  private int kJobId = 0;  @Override  public void onCreate() {    super.onCreate();    Log.i("INFO", "jobService create");  }  @Override  public int onStartCommand(Intent intent, int flags, int startId) {    Log.i("INFO", "jobService start");    scheduleJob(getJobInfo());    return START_NOT_STICKY;  }  @Override  public void onDestroy() {    // TODO Auto-generated method stub    super.onDestroy();  }  @Override  public boolean onStartJob(JobParameters params) {    // TODO Auto-generated method stub    Log.i("INFO", "job start");//   scheduleJob(getJobInfo());    boolean isLocalServiceWork = isServiceWork(this, LocalService.ACTION_LOCAL_SERVICE);    boolean isRemoteServiceWork = isServiceWork        (this, RemoteService.ACTION_REMOTE_SERVICE);//   Log.i("INFO", "localSericeWork:"+isLocalServiceWork);//   Log.i("INFO", "remoteSericeWork:"+isRemoteServiceWork);    if(!isLocalServiceWork||        !isRemoteServiceWork){      //this.startService(new Intent(this,LocalService.class));      startLocalService();      startRemoteService();      //this.startService(new Intent(this,RemoteService.class));      Toast.makeText(this, "process start", Toast.LENGTH_SHORT).show();    }    return true;  }  private void startLocalService(){    Intent testIntent = new Intent();    //自定義的Service的action    testIntent.setAction(LocalService.ACTION_LOCAL_SERVICE);    //自定義Service的包名    testIntent.setPackage(getPackageName());    Log.i("999",getPackageName()+"");    startService(testIntent);  }  private void startRemoteService(){    Intent testIntent = new Intent();    //自定義的Service的action    testIntent.setAction(RemoteService.ACTION_REMOTE_SERVICE);    //自定義Service的包名    testIntent.setPackage(getPackageName());    Log.i("999", getPackageName() + "");    startService(testIntent);  }  @Override  public boolean onStopJob(JobParameters params) {    Log.i("INFO", "job stop");//   Toast.makeText(this, "process stop", Toast.LENGTH_SHORT).show();    scheduleJob(getJobInfo());    return true;  }  /** Send job to the JobScheduler. */  public void scheduleJob(JobInfo t) {    Log.i("INFO", "Scheduling job");    JobScheduler tm =        (JobScheduler) getSystemService(Context.JOB_SCHEDULER_SERVICE);    tm.schedule(t);  }  public JobInfo getJobInfo(){    JobInfo.Builder builder = new JobInfo.Builder(kJobId++, new ComponentName                                                      (this, JobHandleService.class));    builder.setRequiredNetworkType(JobInfo.NETWORK_TYPE_ANY);    builder.setPersisted(true);    builder.setRequiresCharging(false);    builder.setRequiresDeviceIdle(false);    builder.setPeriodic(10);//間隔時間--週期    return builder.build();  }  /**   * 判斷某個服務是否正在執行的方法   *   * @param mContext   * @param serviceName   *      是包名+服務的類名（例如：net.loonggg.testbackstage.TestService）   * @return true代表正在執行，false代表服務沒有正在執行   */  public boolean isServiceWork(Context mContext, String serviceName) {    boolean isWork = false;    ActivityManager myAM = (ActivityManager) mContext        .getSystemService(Context.ACTIVITY_SERVICE);    List<RunningServiceInfo> myList = myAM.getRunningServices(100);    if (myList.size() <= 0) {      return false;    }    for (int i = 0; i < myList.size(); i++) {      String mName = myList.get(i).service.getClassName().toString();      if (mName.equals(serviceName)) {        isWork = true;        break;      }    }    return isWork;  }}

6. 利用賬號同步機制喚醒我們的程序AccountManager7. NDK來解決，Native程序來實現雙程序守護。