进程的重要性优先级：
1. 前台进程：Foreground process
用户正在交互的Activity（onResume()
当某个Service绑定正在交互的Activity
被主动调用为前台的Service(startForeground())
组件正在执行生命周期的回调（(onCreate() /onStart()/onDestory())
BroadcastReceiver 正在执行onReceive()；
2.可见进程：Visible process
我们的Activity处在onPause() (没有进入onStop())
绑定到前台Activity的Service
3.服务进程：Service process
简单的startservice()启动
4.后台进程：Background process
对用户没有直接影响的进程-----Activity处于onStop()的时候
5.空进程 ：Empty process
不含有任何的活动的组件。(android设计的，为了第二次启动更快，采取了一个权衡)
进程越往后越容易被系统杀死
如何不被系统杀死
我们要如何提升进程的优先级(尽量做到不轻易被系统杀死)，提供以下七个方案
1. 模仿QQ采取在锁屏的时候启动1个像素的Activity。
背景：当手机锁屏的时候什么都干死了，为了省电。
监听锁屏广播，锁了---启动这个1像素Activity。
监听锁屏的， 开启---结束掉这个1像素Activity。
要监听锁屏的广播---动态注册。
关键代码：
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(); } }}
源码地址：https://github.com/kpioneer123/KeepLiveProcess
2. 大型App运营商和手机厂商可能有合作关系---白名单
3. 双进程守护
一个进程被杀死，另外一个进程又被他启动，相互监听启动。
A<---->B
杀进程是一个一个杀的，本质是和杀进程时间赛跑。
关键代码：
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); } //启动前台进程 增加重要性优先级 @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，我怕谁!") .setAutoCancel(true) .setContentText("hehehe") .setWhen( System.currentTimeMillis()); //把service设置为前台运行，避免手机系统自动杀掉改服务。 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, "建立连接成功！"); } @Override public void onServiceDisconnected(ComponentName name) { Log.i(TAG, "本地服务被干掉了~~~~~断开连接!"); Toast.makeText(LocalService.this, "断开连接", Toast.LENGTH_SHORT).show(); //启动被干掉的 testIntent = new Intent(); //自定义的Service的action testIntent.setAction(RemoteService.ACTION_REMOTE_SERVICE); //自定义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); } } }
源码地址：https://github.com/kpioneer123/KeepLiveProcess2
4. JobScheduler
把任务加到系统调度队列中，当到达任务窗口期的时候就会执行，我们可以在这个任务里面启动我们的进程。这样可以做到将近杀不死的进程。
@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(); //自定义的Service的action testIntent.setAction(LocalService.ACTION_LOCAL_SERVICE); //自定义Service的包名 testIntent.setPackage(getPackageName()); Log.i("999",getPackageName()+""); startService(testIntent); } private void startRemoteService(){ Intent testIntent = new Intent(); //自定义的Service的action testIntent.setAction(RemoteService.ACTION_REMOTE_SERVICE); //自定义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);//间隔时间--周期 return builder.build(); } /** * 判断某个服务是否正在运行的方法 * * @param mContext * @param serviceName * 是包名+服务的类名（例如：net.loonggg.testbackstage.TestService） * @return true代表正在运行，false代表服务没有正在运行 */ 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; }}
5. 监听QQ,微信，系统应用，友盟，小米推送等等的广播，然后把自己启动了。
6. 利用账号同步机制唤醒我们的进程AccountManager
7. NDK来解决，Native进程来实现双进程守护。
