上篇博客讲了我的保活之旅，这篇说一下“1像素页面保活”的具体实现。
第一步，新建一个Activity，作为1像素页面的主体，我姑且叫它HooliganActivity:

public class HooliganActivity extends Activity {
    private static HooliganActivity instance;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        instance = this;
        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);
    }

    /**
     * 开启保活页面
     */
    public static void startHooligan() {
        Intent intent = new Intent(DWApplication.getAppContext(), HooliganActivity.class);
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        DWApplication.getAppContext().startActivity(intent);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        instance = null;
    }

    /**
     * 关闭保活页面
     */
    public static void killHooligan() {
        if(instance != null) {
            instance.finish();
        }
    }
}

第二步，注册清单文件：

        <activity android:name=".activity.HooliganActivity"
            android:configChanges="keyboardHidden|orientation|screenSize|navigation|keyboard"
            android:excludeFromRecents="true"
            android:exported="false"
            android:finishOnTaskLaunch="false"
            android:launchMode="singleInstance"
            android:theme="@style/HooliganActivityStyle"/>

    <style name="HooliganActivityStyle">
        <item name="android:windowBackground">@color/transparent</item>
        <item name="android:windowContentOverlay">@null</item>
        <item name="android:windowIsTranslucent">true</item>
        <item name="android:windowNoDisplay">false</item>
        <item name="android:windowDisablePreview">true</item>
    </style>

第三步，监听锁屏和解锁通知，不能静态注册广播，只能动态注册：

IntentFilter filter = new IntentFilter();
filter.addAction(Intent.ACTION_SCREEN_ON);
filter.addAction(Intent.ACTION_SCREEN_OFF);
registerReceiver(new BootCompleteReceiver(),filter);

第四步，分别在解锁和锁屏时唤醒我的HooliganActivity：

public class BootCompleteReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        if(intent.getAction().equals(Intent.ACTION_SCREEN_OFF)) {
            HooliganActivity. startHooligan();
        } else if(intent.getAction().equals(Intent.ACTION_SCREEN_ON)){
            HooliganActivity. killHooligan();
        }
    }
}

这样你在后台每次锁屏，实际上都会吊起一个一像素的页面，假装app在前台，拥有最高进程优先级。
  不推荐使用，太流氓了- -！。

技术无罪。
                               ——王欣

但人有罪。