Android 判定APP是否启动、Activity是否运行，通过Service来启动已关闭的Activity

    private static final String packageName = "com.example.scangundemo_as";
    private static final String className = "MainActivity";

1、判定APP是否启动

    public static boolean isAppAlive(Context context, String packageName) {
        ActivityManager activityManager =
                (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
        List<ActivityManager.RunningAppProcessInfo> processInfos
                = activityManager.getRunningAppProcesses();
        for (int i = 0; i < processInfos.size(); i++) {
            Log.i("Service","--------processname="+processInfos.get(i).processName);
            if (processInfos.get(i).processName.equals(packageName)) {
                return true;
            }
        }
        return false;
    }

2、判定Activity是否运行

    public static boolean isRunningForeground (Context context) {
        ActivityManager am = (ActivityManager)context.getSystemService(Context.ACTIVITY_SERVICE);
        ComponentName cn = am.getRunningTasks(1).get(0).topActivity;
        String currentPackageName = cn.getPackageName();
        if(!TextUtils.isEmpty(currentPackageName) && currentPackageName.equals(context.getPackageName())) {
            return true ;
        }
        return false ;
    }

3、通过Service来启动已关闭的Activity

  3.1）、service

package com.example.scangundemo_as;

import android.app.ActivityManager;
import android.app.Service;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.pm.ApplicationInfo;
import android.content.res.Resources;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.text.TextUtils;
import android.util.Log;

import java.util.List;
import java.util.logging.Logger;

public class APPService extends Service {

    private static final String packageName = "com.example.scangundemo_as";
    private static final String className = "MainActivity";

    @Override
    public void onCreate() {
        super.onCreate();
        Log.i("Service","-------create-------");
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Log.i("Service","-------onDestroy-------");
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.i("Service","-----service onStartCommand...");
        new Thread(){
            @Override
            public void run() {
                super.run();
                while(true){
                    try {
                        Thread.sleep(5000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    //一直运行
                    boolean isRunningForeground = isRunningForeground(APPService.this);
//                    Log.i("Service","-----service isRunningForeground="+isRunningForeground);
                    if(!isRunningForeground){
                        Log.i("Service","-----start activity-----");
                        startActivityTool(APPService.this);
                    }
                }
            }
        }.start();
        return super.onStartCommand(intent, flags, startId);
    }

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

    public static boolean isAppAlive(Context context, String packageName) {
        ActivityManager activityManager =
                (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
        List<ActivityManager.RunningAppProcessInfo> processInfos
                = activityManager.getRunningAppProcesses();
        for (int i = 0; i < processInfos.size(); i++) {
            Log.i("Service","--------processname="+processInfos.get(i).processName);
            if (processInfos.get(i).processName.equals(packageName)) {
                return true;
            }
        }
        return false;
    }


    public static boolean isRunningForeground (Context context) {
        ActivityManager am = (ActivityManager)context.getSystemService(Context.ACTIVITY_SERVICE);
        ComponentName cn = am.getRunningTasks(1).get(0).topActivity;
        String currentPackageName = cn.getPackageName();
        if(!TextUtils.isEmpty(currentPackageName) && currentPackageName.equals(context.getPackageName())) {
            return true ;
        }
        return false ;
    }

    public static void startActivityTool(Context context){
        Intent intent = new Intent();
        intent.setClass(context, MainActivity.class);
        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK );
        context.startActivity(intent);
    }


}

 3.2）、清单AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.scangundemo_as">

    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.CHANGE_NETWORK_STATE"/>
    <uses-permission android:name="android.permission.CHANGE_WIFI_STATE"/>

    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />


    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.AppCompat.Light.NoActionBar">
        <activity android:name=".MainActivity"
            android:windowSoftInputMode="stateAlwaysHidden">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <service android:name=".APPService" android:enabled="true" android:exported="true">
        </service>
        <receiver android:name=".BootBroadcastReceiver">
            <intent-filter>
                <action android:name="android.intent.action.BOOT_COMPLETED"></action>
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </receiver>

    </application>

</manifest>

 3.3)、MainActivity

public class MainActivity extends AppCompatActivity {

    private static final String TAG  = "MainActivity";
    private static final int RUNNING_INTERVAL = 5000;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //启动service
        Intent intent = new Intent(this,APPService.class);
        startService(intent);

    }

    @Override
    public void onDestroy(){

        super.onDestroy();
    }
}