保活（四）-1px Acticity

1.原理

当屏幕熄灭的时候呢，锁屏状态，调起一个一像素的Activity,为的还是能够提高进程的优先级，在上一篇文章中，有详细的进程优先级的情况

2.Activity

public class OnePxActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Window window = getWindow();
        window.setGravity(Gravity.LEFT | Gravity.TOP);
        WindowManager.LayoutParams params = window.getAttributes();
        params.x = 0;
        params.y = 0;
        params.height = 1;
        params.width = 1;
        window.setAttributes(params);
        Log.i("stf", "--onCreate--->OnePxActivity");
    }

    @Override
    public void onResume() {
        super.onResume();
        Log.i("stf", "--onResume--->OnePxActivity");
        checkScreen();
    }

    
    /**
     * @author  stf
     * @time    2018-06-13 14:16
     * @remark  检查屏幕状态  isScreenOn为true  屏幕“亮”
     *
     */
    private void checkScreen() {
        PowerManager pm = (PowerManager) OnePxActivity.this.getSystemService(Context.POWER_SERVICE);
        boolean isScreenOn = pm.isScreenOn();
        Log.i("stf", "-屏幕状态-isScreenOn--->" + isScreenOn);
        if (isScreenOn) {
         Log.i("stf", "--关闭该Act--->OnePxActivity");
           finish();
        }
    }
  }

3.广播

// 屏幕状态检测广播
public class OnePixelReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Log.i("stf", "--OnePixelReceiver-->" + intent.getAction());
        //屏幕关闭启动1像素Activity
        if (intent.getAction().equals(Intent.ACTION_SCREEN_OFF) || intent.getAction().equals(Intent.ACTION_USER_PRESENT)) {
            Log.i("stf", "--OnePixelReceiver-->启动OnePxActivity");
             try {
                Intent it = new Intent(context, OnePxActivity.class);
                it.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                context.startActivity(it);
            } catch (Exception e) {
                e.fillInStackTrace();
            }
        }
    }
}

4.清单文件

     <activity
            android:name=".activity.OnePxActivity"
            android:configChanges="keyboardHidden|orientation|screenSize|navigation|keyboard"
            android:excludeFromRecents="true"
            android:finishOnTaskLaunch="false"
            android:launchMode="singleInstance"
            android:screenOrientation="portrait"
            android:theme="@style/OnePixelActivity" />

5.透明主题

<style name="OnePxActStyle" parent="Theme.AppCompat.Light.NoActionBar">
        <!-- 窗体背景颜色为透明 -->
        <item name="android:windowBackground">@android:color/transparent</item>
        <!-- 窗体没有边框 -->
        <item name="android:windowFrame">@null</item>
        <!-- 窗体不包含标题栏 -->
        <item name="android:windowNoTitle">true</item>
        <!-- 窗体悬浮 -->
        <item name="android:windowIsFloating">true</item>
        <!-- 自定义TitleBar时去掉多余的阴影-->
        <item name="android:windowContentOverlay">@null</item>
        <!-- 不允许窗体背景变暗-->
        <item name="android:backgroundDimEnabled">false</item>
        <!-- 窗体切换无动画-->
        <item name="android:windowAnimationStyle">@null</item>
        <!-- 禁用窗口的预览动画-->
        <item name="android:windowDisablePreview">true</item>
        <item name="android:windowNoDisplay">false</item>
        <item name="android:windowIsTranslucent">true</item>
    </style>

6.注册广播

分为静态注册和动态注册：
静态注册时 android.intent.action.SCREEN_OFF 不会被触发
动态注册 则没有问题，经实测发现，当App进度后台时收到广播后无法跳转到1PXAct。
这里还是采取静态注册。

首先需要在启动广播的位置注册一个监听手机屏幕状态的广播监听（比如MainActivity）

        <receiver android:name=".Receiver.OnePixelReceiver">
            <intent-filter>
                <action android:name="android.intent.action.SCREEN_OFF" />
                <action android:name="android.intent.action.USER_PRESENT" />
            </intent-filter>
        </receiver>

7.运行结果

关闭屏幕 再点亮屏幕
--OnePixelReceiver-->android.intent.action.USER_PRESENT
--OnePixelReceiver-->启动OnePxActivity
--onCreate--->OnePxActivity
--onResume--->OnePxActivity
-屏幕状态-isScreenOn--->true
--关闭该Act--->OnePxActivity

参考资料

1像素 Activity