android 判断应用是否在后台运行和判断当前进程是否在主进程

1.判断应用是否在后台运行(两种方式)

/**
     * 判断程序是否在后台
     * @param context
     * @return
     */
    public static boolean isBackground(Context context) {
        ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
        List<ActivityManager.RunningAppProcessInfo> appProcesses = activityManager.getRunningAppProcesses();
        for (ActivityManager.RunningAppProcessInfo appProcess : appProcesses) {
            if (appProcess.processName.equals(context.getPackageName())) {
                if (appProcess.importance != ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
                    return true;
                } else {
                    return false;
                }
            }
        }
        return false;
    }

或者

public static boolean isApplicationInBackground(Context context) {
            ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
            List<ActivityManager.RunningTaskInfo> taskList = am.getRunningTasks(1);
            if (taskList != null && !taskList.isEmpty()) {
                ComponentName topActivity = taskList.get(0).topActivity;
                if (topActivity != null && !topActivity.getPackageName().equals(context.getPackageName())) {
                    return true;
                }
            }
            return false;
        }

或者全局监听（推荐）

object AppFrontBack {
    /**
     * 打开的Activity数量统计
     */
    private var activityStartCount = 0

    /**
     * 注册状态监听，仅在Application中使用
     * @param application
     * @param listener
     */
    fun register(application: Application, listener: AppFrontBackListener) {
        application.registerActivityLifecycleCallbacks(object : Application.ActivityLifecycleCallbacks {
            override fun onActivityPaused(activity: Activity) {
            }

            override fun onActivityResumed(activity: Activity) {
            }

            override fun onActivityDestroyed(activity: Activity) {
            }

            override fun onActivitySaveInstanceState(activity: Activity, outState: Bundle) {
            }

            override fun onActivityCreated(activity: Activity, savedInstanceState: Bundle?) {
            }

            override fun onActivityStarted(activity: Activity) {
                activityStartCount++
                if (activityStartCount == 1) {
                    listener.onFront(activity)
                }
            }

            override fun onActivityStopped(activity: Activity) {
                activityStartCount--
                if (activityStartCount == 0) {
                    listener.onBack(activity)
                }
            }

        })
    }
}

/**
 * App状态监听
 */
interface AppFrontBackListener {
    /**
     * 前台
     */
    fun onFront(activity: Activity?)

    /**
     * 后台
     */
    fun onBack(activity: Activity?)
}

使用时：

/**
     * 注册APP前后台切换监听
     */
    private fun appFrontBackRegister() {
        AppFrontBack.register(this, object : AppFrontBackListener {
            override fun onBack(activity: Activity?) {
                LogUtil.d("onBack")
            }

            override fun onFront(activity: Activity?) {
                LogUtil.d("onFront")
            }
        })
    }

2.判断进程是否在主进程

public static boolean isMainProcess(Context context) {
        if (context == null) {
            return false;
        }

        String packageName = context.getApplicationContext().getPackageName();
        String processName = getProcessName(context);
        return packageName.equals(processName);
    }
public static String getProcessName(Context context) {
        String processName = getProcessFromFile();
        if (processName == null) {
            // 如果装了xposed一类的框架，上面可能会拿不到，回到遍历迭代的方式
            processName = getProcessNameByAM(context);
        }
        return processName;
    }
private static String getProcessFromFile() {
        BufferedReader reader = null;
        try {
            int pid = android.os.Process.myPid();
            String file = "/proc/" + pid + "/cmdline";
            reader = new BufferedReader(new InputStreamReader(new FileInputStream(file), "iso-8859-1"));
            int c;
            StringBuilder processName = new StringBuilder();
            while ((c = reader.read()) > 0) {
                processName.append((char) c);
            }
            return processName.toString();
        } catch (Exception e) {
            return null;
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
private static String getProcessNameByAM(Context context) {
        String processName = null;

        ActivityManager am = ((ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE));
        if (am == null) {
            return null;
        }

        while (true) {
            List<ActivityManager.RunningAppProcessInfo> plist = am.getRunningAppProcesses();
            if (plist != null) {
                for (ActivityManager.RunningAppProcessInfo info : plist) {
                    if (info.pid == android.os.Process.myPid()) {
                        processName = info.processName;

                        break;
                    }
                }
            }

            if (!TextUtils.isEmpty(processName)) {
                return processName;
            }

            try {
                Thread.sleep(100L); // take a rest and again
            } catch (InterruptedException ex) {
                ex.printStackTrace();
            }
        }
    }