【Android实例】1像素保活实例

1 进程保活

1像素保活原理是，监听手机屏幕状态，如果手机黑屏，则启动一个1像素的Activity，减少该应用被回收的几率；在屏幕亮的时候，就关闭该Activity。1像素保活对某些手机不管用，亲测两款手机：红米5Note（Android 9）和华为G9青春版（Android 6.0）。

测试方法：看是否调用1像素Activity。在打开应用，然后息屏情况下，两款手机都会调用1像素Activity；打开应用，然后点home键，再息屏，华为G9青春版（Android 6.0）会调用1像素Activity，但是红米5Note（Android 9）则不会调用。

2管理类OnePixelManager

首先建立一个OnePixelManager，该类是一个管理类。代码如下

package com.yds.jianshu.onepixel;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;

import java.lang.ref.WeakReference;

public class OnePixelManager {
    private static final String TAG = "[OnePixelManager]";
    private WeakReference<Activity> mActivity;
    private OnePixelReceiver onePixelReceiver;

    /**
     * 一像素广播接收者注册方法。该方法中初始化OnePixelReceiver，并添加了过滤条件
     * 屏幕息屏和亮屏。然后注册该广播接收者
     * @param context
     */
    public void registerOnePixelReceiver(Context context){
        IntentFilter filter = new IntentFilter();
        filter.addAction(Intent.ACTION_SCREEN_OFF);
        filter.addAction(Intent.ACTION_SCREEN_ON);
        onePixelReceiver = new OnePixelReceiver();
        context.registerReceiver(onePixelReceiver,filter);
    }

    /**
     * 对广播接收者进行解注册
     * @param context
     */
    public void unregisterOnePixelReceiver(Context context){
        if (null != onePixelReceiver){
            context.unregisterReceiver(onePixelReceiver);
        }
    }

    /**
     * 开启一像素Activity
     * @param context
     */
    public void startOnePixelActivity(Context context){
        Intent intent = new Intent();
        intent.setClass(context,OnePixelActivity.class);
        context.startActivity(intent);
    }

    /**
     * 关闭一像素Activity
     */
    public void finishOnePixelActivity(){
        if(null!=mActivity){
            Activity activity = mActivity.get();
            if(null!=activity){
                activity.finish();
            }
            mActivity = null;
        }
    }

    /**
     * 使用弱引用获取一像素的上下文
     * @param activity
     */
    public void setKeepAliveReference(OnePixelActivity activity){
        mActivity = new WeakReference<Activity>(activity);
    }

}

3 广播接收系统发送的广播

写一个一像素的广播接收者，接收息屏和亮屏时的广播

package com.yds.jianshu.onepixel;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;


public class OnePixelReceiver extends BroadcastReceiver {
    private static final String TAG = "[OnePixelReceiver]";
    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        OnePixelManager manager = new OnePixelManager();
        if (Intent.ACTION_SCREEN_ON.equals(action)){//如果亮屏，则关闭1像素Activity
            manager.finishOnePixelActivity();
        }else if(Intent.ACTION_SCREEN_OFF.equals(action)){//如果息屏，则开启1像素Activity
            manager.startOnePixelActivity(context);
        }
    }
}

4 一像素Activity

创建一个1像素的Activity，并将引用传给OnePixelManager

package com.yds.jianshu.onepixel;

import android.app.Activity;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.util.Log;
import android.view.Gravity;
import android.view.Window;
import android.view.WindowManager;

public class OnePixelActivity extends Activity{
    private static final String TAG = "[OnePixelActivity]";
    @Override
    protected void onCreate(@Nullable 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);
        OnePixelManager manager = new OnePixelManager();
        manager.setKeepAliveReference(this);//将引用传给OnePixelManager

        Log.e(TAG,"onCreate");
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        Log.e(TAG,"onDestroy");
    }

    @Override
    protected void onStop() {
        super.onStop();
        Log.e(TAG,"onStop");
    }

    @Override
    protected void onPause() {
        super.onPause();
        Log.e(TAG,"onPause");
    }

    @Override
    protected void onStart() {
        super.onStart();
        Log.e(TAG,"onStart");
    }

    @Override
    protected void onResume() {
        super.onResume();
        Log.e(TAG,"onResume");
    }
}

5 MainActivity方法调用

package com.yds.jianshu.mobile;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

import com.example.myapplication.R;
import com.yds.jianshu.onepixel.OnePixelManager;

public class MainActivity extends AppCompatActivity{
    private static final String TAG = "[MainActivity]";
    OnePixelManager manager;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        manager = new OnePixelManager();
        manager.registerOnePixelReceiver(this);//注册广播接收者
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        manager.unregisterOnePixelReceiver(this);//Activity退出时解注册
    }
}

6 AndroidManifest配置

在OnePixelActivity注册的地方要加上以下三句

            android:excludeFromRecents="true"//#1
            android:launchMode="singleTask"//#2
            android:taskAffinity="com.yds.task"//#3

• 第#1行，是为了让我们的1像素Activity在recents中看到，就是说，点击任务键（Android手机屏幕下三个键中的右边的键，一般是正方形那个）时不会看到OnePixelActivity
• 第#2行，将启动模式设置为singleTask模式，配合taskAffinity使用。如果不设置，华为G9青春版（Android 6.0）会有问题，有时会创建多个OnePixelActivity，多次息屏亮屏，可能出现屏幕点不动，点击返回键后就正常，是因为创建了多个OnePixelActivity，通过打log日志也可以看出创建了多个OnePixelActivity。
• 第#3行，将创建的OnePixelActivity放入指定的任务栈中

代码如下：

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myapplication">

    <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/AppTheme">
        <activity android:name="com.yds.jianshu.mobile.MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            intent-filter>
        activity>
        <activity android:name="com.yds.jianshu.onepixel.OnePixelActivity"
            android:excludeFromRecents="true"
            android:launchMode="singleTask"
            android:taskAffinity="com.yds.task"
            android:theme="@style/OnePixelActivity">
        activity>
    application>

manifest>

7 优化部分

将OnePixelActivity背景设置为透明

<resources>

    
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        
        "colorPrimary">@color/colorPrimary
        "colorPrimaryDark">@color/colorPrimaryDark
        "colorAccent">@color/colorAccent
    style>
    
    <style name="OnePixelActivity" parent="android:Theme.Holo.Light.NoActionBar">//无标题
        "android:windowIsTranslucent">true//透明
    style>
resources>