Android Surfaceview 线程和内存泄漏

Question

我在 android 中创建游戏，我注意到该游戏存在内存泄漏。我设法将内存泄漏隔离到一个较小的应用程序中，这样我就可以很好地了解如何解决它。

该应用程序为其 View 使用表面 View ，并附加了一个线程，以便将所有绘图绘制到屏幕上。当我开始一项新 Activity 并关闭我当前正在使用的 Activity 时，就会发生内存泄漏。当我在我的测试应用程序上进行内存转储时，我可以看到这一点，因为它所做的只是打开和关闭一个 Activity ( Activity a -> Activity b -> Activity a)。关于如何解决这个问题，我有点想不通了，因为我试图让我对 View (在线程内)创建的所有引用都无效，当我销毁 View 时，我尝试从表面 View 中删除回调，而且在 Activity 中，它似乎没有任何区别。

内存泄漏 Activity .java

package memory.leak;

import memory.leak.view.MemoryLeak;
import android.app.Activity;
import android.os.Bundle;

public class MemoryLeakActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new MemoryLeak(this));
    }
}

MemoryLeakViewThread.java

package memory.leak.thread;

import memory.leak.view.MemoryLeak;
import android.view.SurfaceHolder;
import android.graphics.Canvas;


public class MemoryLeakViewThread extends Thread {
    private MemoryLeak view;
    private boolean run =false;

    public MemoryLeakViewThread(MemoryLeak view) {
        this.view =view;
    }

    public void setRunning(boolean run) {
        this.run =run;
    }

    @Override
    public void run() {
        Canvas canvas =null;
        SurfaceHolder holder =this.view.getHolder();
        while(this.run) {
            canvas =holder.lockCanvas();
            if(canvas !=null) {
                this.view.onDraw(canvas);
                holder.unlockCanvasAndPost(canvas);
            }
        }
        holder =null;
        this.view =null;
    }
}

内存泄漏.java

package memory.leak.view;

import memory.leak.TestActivity;
import memory.leak.thread.MemoryLeakViewThread;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Canvas;
import android.graphics.Color;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.GestureDetector.OnGestureListener;


public class MemoryLeak extends SurfaceView implements SurfaceHolder.Callback, OnGestureListener {
    private GestureDetector gesture;
    private MemoryLeakViewThread vThread;
    private Context context;

    public MemoryLeak(Context context) {
        super(context);

        this.getHolder().addCallback(this);
        this.vThread =new MemoryLeakViewThread(this);

        this.gesture =new GestureDetector(this);
        this.context =context;
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}

    public void surfaceCreated(SurfaceHolder holder) {
        if(!this.vThread.isAlive()) {
            this.vThread =new MemoryLeakViewThread(this);
            this.vThread.setRunning(true);
            this.vThread.start();
        }
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        boolean retry = true;

        if(this.vThread.isAlive()) {
            this.vThread.setRunning(false);
            while(retry) {
                try {
                    this.vThread.join();
                    retry =false;
                } catch(Exception ee) {}
            }
        }

        this.vThread =null;
        this.context =null;
    }

     public boolean onTouchEvent(MotionEvent event) {
         return this.gesture.onTouchEvent(event);
     }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    }

    @Override
    public void onDraw(Canvas canvas) {
        canvas.drawColor(Color.WHITE);
    }   

    @Override
    public boolean onDown(MotionEvent e) {
        return true;
    }

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
        return false;
    }

    @Override
    public void onLongPress(MotionEvent e) {}

    @Override
    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
        return false;
    }

    @Override
    public void onShowPress(MotionEvent e) {}

    @Override
    public boolean onSingleTapUp(MotionEvent e) {
        Intent helpScreenIntent =new Intent(this.context, TestActivity.class);
        this.context.startActivity(helpScreenIntent);

        if (this.context instanceof Activity)
            ((Activity) this.context).finish();

        return true;
    }
}

测试 Activity .java

package memory.leak;

import memory.leak.view.Test;
import android.app.Activity;
import android.os.Bundle;

public class TestActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new Test(this));
    }
}

TestViewThread.java

package memory.leak.thread;

import memory.leak.view.Test;
import android.view.SurfaceHolder;
import android.graphics.Canvas;


public class TestViewThread extends Thread {
    private Test panel;
    private boolean run =false;

    public TestViewThread(Test panel) {
        this.panel =panel;
    }

    public void setRunning(boolean run) {
        this.run =run;
    }

    @Override
    public void run() {
        Canvas canvas =null;
        SurfaceHolder holder =this.panel.getHolder();
        while(this.run) {
            canvas =holder.lockCanvas();
            if(canvas !=null) {
                this.panel.onDraw(canvas);
                holder.unlockCanvasAndPost(canvas);
            }
        }
        holder =null;
        this.panel =null;
    }
}

测试.java

package memory.leak.view;

import memory.leak.MemoryLeakActivity;
import memory.leak.thread.TestViewThread;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Canvas;
import android.graphics.Color;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.GestureDetector.OnGestureListener;


public class Test extends SurfaceView implements SurfaceHolder.Callback, OnGestureListener {
    private GestureDetector gesture;
    private TestViewThread vThread;
    private Context context;

    public Test(Context context) {
        super(context);

        this.getHolder().addCallback(this);
        this.vThread =new TestViewThread(this);

        this.gesture =new GestureDetector(this);
        this.context =context;
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}

    public void surfaceCreated(SurfaceHolder holder) {
        if(!this.vThread.isAlive()) {
            this.vThread =new TestViewThread(this);
            this.vThread.setRunning(true);
            this.vThread.start();
        }
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        boolean retry = true;

        if(this.vThread.isAlive()) {
            this.vThread.setRunning(false);
            while(retry) {
                try {
                    this.vThread.join();
                    retry =false;
                } catch(Exception ee) {}
            }
        }

        this.vThread =null;
        this.context =null;
    }

     public boolean onTouchEvent(MotionEvent event) {
         return this.gesture.onTouchEvent(event);
     }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    }

    @Override
    public void onDraw(Canvas canvas) {
        canvas.drawColor(Color.RED);
    }   

    @Override
    public boolean onDown(MotionEvent e) {
        return true;
    }

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
        return false;
    }

    @Override
    public void onLongPress(MotionEvent e) {}

    @Override
    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
        return false;
    }

    @Override
    public void onShowPress(MotionEvent e) {}

    @Override
    public boolean onSingleTapUp(MotionEvent e) {
        Intent helpScreenIntent =new Intent(this.context, MemoryLeakActivity.class);
        this.context.startActivity(helpScreenIntent);

        if (this.context instanceof Activity)
            ((Activity) this.context).finish();

        return true;
    }
}

--编辑--我对 View 类的 surfaceDestroyed(SurfaceHolder holder) 进行了更改，以便在告知线程停止时将线程必须设置为 null 的 View 。我所做的更改是

public void surfaceDestroyed(SurfaceHolder holder) {
        boolean retry = true;

        if(this.vThread.isAlive()) {
            this.vThread.setRunning(false);
            while(retry) {
                try {
                    this.vThread.join();
                    retry =false;
                } catch(Exception ee) {}
            }
            this.vThread.setRunning(false, null);
        }

        this.vThread =null;
        this.context =null;
        this.gesture =null;
    }

您还需要将 surfaceCreated(SurfaceHolder holder) 方法更改为

public void surfaceCreated(SurfaceHolder holder) {
        if(!this.vThread.isAlive()) {
            this.vThread =new MemoryLeakViewThread();
            this.vThread.setRunning(true, this);
            this.vThread.start();
        }
    }

然后在线程类上我们需要更改以下内容

public MemoryLeakViewThread() {
    }

    public void setRunning(boolean run) {
        this.run =run;
    }

    public void setRunning(boolean run, MemoryLeak view) {
        this.run =run;
        this.view =view;
    }

这样做似乎解决了问题，现在唯一的问题是由于线程类和线程组，线程似乎停留在内存中。但我认为这可能是调试器的问题。

Answer 1

在 onSurfaceCreated 中创建线程时，不应在构造函数中创建新线程。将您的代码与我的示例进行比较:How can I use the animation framework inside the canvas?