Android4.4 灭屏kill第三方app

在android4.4上添加功能当手机短按power键，灭屏的时候。kill三方的app进程。

在我之前的博客中分析过，按键处理，会从InputManager的native层，先到PhoneWindowManager的interceptKeyBeforeQueueing函数，先对按键进行处理，比如power键，会禁止把这Event传给应用。

下来我们来看下源码实现：

@Override
    public int interceptKeyBeforeQueueing(KeyEvent event, int policyFlags, boolean isScreenOn) {
..........
        int result;
        if ((isScreenOn && !mHeadless) || (isInjected && !isWakeKey)) {
            // When the screen is on or if the key is injected pass the key to the application.
            result = ACTION_PASS_TO_USER;
        } else {
            // When the screen is off and the key is not injected, determine whether
            // to wake the device but don't pass the key to the application.
            result = 0;
            if (down && isWakeKey && isWakeKeyWhenScreenOff(keyCode) && !mRejectShortPressPowerKey) {
                result |= ACTION_WAKE_UP;
sendBootCompleted();//新加，杀了进程之后，起开的时候发一个开机广播，防止有些应用是根据这个广播启动的
            }
        }
...........


            case KeyEvent.KEYCODE_POWER: {
                result &= ~ACTION_PASS_TO_USER;
                if (down) {
                    mImmersiveModeConfirmation.onPowerKeyDown(isScreenOn, event.getDownTime(),
                            isImmersiveMode(mLastSystemUiFlags));
                    if (isScreenOn && !mPowerKeyTriggered
                            && (event.getFlags() & KeyEvent.FLAG_FALLBACK) == 0) {
                        mPowerKeyTriggered = true;
                        mPowerKeyTime = event.getDownTime();
                        interceptScreenshotChord();
                    }

                    ITelephony telephonyService = getTelephonyService();
                    boolean hungUp = false;
                    if (telephonyService != null) {
                        try {
                            if (telephonyService.isRinging()) {
                                // Pressing Power while there's a ringing incoming
                                // call should silence the ringer.
                                telephonyService.silenceRinger();
                            } else if ((mIncallPowerBehavior
                                    & Settings.Secure.INCALL_POWER_BUTTON_BEHAVIOR_HANGUP) != 0
                                    && telephonyService.isOffhook()) {
                                // Otherwise, if "Power button ends call" is enabled,
                                // the Power button will hang up any current active call.
                                hungUp = telephonyService.endCall();
                            }
                        } catch (RemoteException ex) {
                            Log.w(TAG, "ITelephony threw RemoteException", ex);
                        }
                    }
                    Log.i(TAG, "PowerKey down, isScreenOn = " + isScreenOn);
                    interceptPowerKeyDown(!isScreenOn || hungUp
                            || mVolumeDownKeyTriggered || mVolumeUpKeyTriggered);
                } else {
                    Log.i(TAG, "PowerKey up");
                    mPowerKeyTriggered = false;
                    cancelPendingScreenshotChordAction();
                    if (interceptPowerKeyUp(canceled || mPendingPowerKeyUpCanceled)) {
                        result = (result & ~ACTION_WAKE_UP) | ACTION_GO_TO_SLEEP;
                        KillProcess();//到kill进程的函数
                    }
                    mPendingPowerKeyUpCanceled = false;
                }
                break;
            }
........
}

代码中在返回result的标志位有ACTION_GO_TO_SLEEP的时候，开启kill进程，返回ACTION_WAKE_UP的时候，发送开机广播（防止一些应用根据开机广播启动）

至于这个goToSleep和wakeUp的处理，and4.4和5.1有差别。4.4是InputManager的native层根据PhoneWindowManager返回的flag，然后在native层去调PowerManagerService的goToSleep和wakeup函数。而5.1之后就直接在PhoneWindowManager中去调PowerManagerService的这两个函数。没有在native层绕了一把。

下面我们再看下killProcess这个函数：

    private void sendBootCompleted() {//发送开机广播
        Intent intent = new Intent(Intent.ACTION_BOOT_COMPLETED);
        mContext.sendBroadcast(intent);
    }

    private void KillProcess() {
        List<ActivityManager.RunningAppProcessInfo> appProcessList = null;
        appProcessList = mActivityManager.getRunningAppProcesses();//获取运行的app列表

        for (ActivityManager.RunningAppProcessInfo appProcessInfo : appProcessList) {
            int pid = appProcessInfo.pid;
            int uid = appProcessInfo.uid;
            String processName = appProcessInfo.processName;
    PackageManager pm = mContext.getPackageManager();
    try {
        ApplicationInfo appinfo = pm.getApplicationInfo(processName, 0);//获取applicationinfo
    boolean isSystemApp = (appinfo.flags & ApplicationInfo.FLAG_SYSTEM) == 1;//判断是否系统应用
        if (!isSystemApp) {
        Log.d(TAG, "process '" + processName + "' will be killed");
                    mActivityManager.forceStopPackage(processName);
        }
    } catch(NameNotFoundException e) {
        Log.e(TAG, "can not find processName:" + processName);
    }
        }
    }