android守护进程，进入后台或异常后再次启动app

当前做的app要求开机启动，并且退出后或异常闪退时也要重新打开app。下面说一下进入后台后或闪退后重启进入前台方法
方法1、缺点：出现异常闪退时，不会重启，因为没来及进onActivityStoppedprivate int mFinalCount;

/**
* 在application中调用，进入一个activity时执行onActivityStarted，离开一个activity时执行onActivityStopped
*/
private void ActivitiesLifeCallbacks()
{
registerActivityLifecycleCallbacks(new ActivityLifecycleCallbacks() {
@Override
public void onActivityCreated(Activity activity, Bundle bundle) {

}

@Override
public void onActivityStarted(Activity activity) {
mFinalCount++;
//如果mFinalCount ==1，说明是从后台到前台
Log.e("onActivityStarted", mFinalCount +"");
if (mFinalCount == 1){
//说明从后台回到了前台
}
}

@Override
public void onActivityResumed(Activity activity) {

}

@Override
public void onActivityPaused(Activity activity) {

}

@Override
public void onActivityStopped(Activity activity) {
mFinalCount--;

//如果mFinalCount ==0，说明是前台到后台
Log.i("onActivityStopped", mFinalCount +"");
if (mFinalCount == 0){
//说明从前台回到了后台
try {
//此处需加延时几秒，否则按home键后回不到前台
Thread.sleep(10000);
} catch (InterruptedException e) {
e.printStackTrace();
}
toFront();
}
}

@Override
public void onActivitySaveInstanceState(Activity activity, Bundle bundle) {

}

@Override
public void onActivityDestroyed(Activity activity) {

}
});
}

/**
* 由后台进入前台
*/
private void toFront()
{
//获取ActivityManager
ActivityManager mAm = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
//获得当前运行的task
List<ActivityManager.RunningTaskInfo> taskList = mAm.getRunningTasks(100);
for (ActivityManager.RunningTaskInfo rti : taskList) {
//找到当前应用的task，并启动task的栈顶activity，达到程序切换到前台
if (rti.topActivity.getPackageName().equals(getPackageName())) {
mAm.moveTaskToFront(rti.id, 0);
return;
}
}
//若没有找到运行的task，用户结束了task或被系统释放，则重新启动mainactivity
Intent resultIntent = new Intent(this, SplashActivity.class);
resultIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_SINGLE_TOP);
startActivity(resultIntent);
}方法2、缺点需要创建service，以及线程，暂用大量CPU时间；切换至后台运行时会有延迟。不过没多大影响，而且闪退时可以重启，目前用这个import android.app.ActivityManager;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.util.Log;

import com.rb.esc.activity.SplashActivity;

import java.util.List;

/**
* 监听前后台
* Created by Administrator on 2018/3/3.
*/

public class AppService extends Service implements Runnable
{
public static boolean isOnForeground = true;

@Nullable
@Override
public IBinder onBind(Intent intent) {
return null;
}

@Override
public void onCreate() {
super.onCreate();

new Thread(this).start();
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
return super.onStartCommand(intent, flags, startId);
}

@Override
public void run() {
while(true){
boolean isOnForegroundNew = isRunningOnForeground(this);

if(isOnForegroundNew != isOnForeground){
toFront();
}
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

public static boolean isRunningOnForeground(Context context){

ActivityManager acm = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
if(acm != null){
List<ActivityManager.RunningAppProcessInfo> runApps = acm.getRunningAppProcesses();
if(runApps != null && !runApps.isEmpty()){
for(ActivityManager.RunningAppProcessInfo app : runApps){
if(app.processName.equals(context.getPackageName())){
if(app.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND){
return true;
}
}
}
}
}
return false;
}

private void toFront()
{
//获取ActivityManager
ActivityManager mAm = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
//获得当前运行的task
List<ActivityManager.RunningTaskInfo> taskList = mAm.getRunningTasks(100);
for (ActivityManager.RunningTaskInfo rti : taskList) {
//找到当前应用的task，并启动task的栈顶activity，达到程序切换到前台
if (rti.topActivity.getPackageName().equals(getPackageName())) {
mAm.moveTaskToFront(rti.id, 0);
return;
}
}
//若没有找到运行的task，用户结束了task或被系统释放，则重新启动mainactivity
Intent resultIntent = new Intent(this, SplashActivity.class);
resultIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_SINGLE_TOP);
startActivity(resultIntent);

}
}
xml中<service android:name=".service.AppService"
android:enabled="true"
android:exported="true"></service>启动时Intent intent = new Intent(this, AppService.class);
startService(intent);