Question

我正在开发2.3版本的Android游戏，并开始在更多设备上进行测试，以便我可以发布它。

在某些情况下，并非所有4.0设备都会在最小化时崩溃。你可以锁定手机并将其解锁，然后游戏恢复并暂停。当您尝试返回主屏幕时发生崩溃。

错误日志如下所示：

07-18 14:33:44.839 E/AndroidRuntime(15542)FATAL EXCEPTION: Thread-662
07-18 14:33:44.839 E/AndroidRuntime(15542)java.lang.NullPointerException
07-18 14:33:44.839 E/AndroidRuntime(15542)at com.petronicarts.stormthecastle.MainThread.run(MainThread.java:55)
07-18 14:33:44.846 W/IInputConnectionWrapper(15542)showStatusIcon on inactive InputConnection
07-18 14:33:45.081 I/ActivityManager(178)No longer want com.android.packageinstaller (pid 15351): hidden #16
07-18 14:33:45.143 W/InputDispatcher(178)channel '41bb4d28 com.android.packageinstaller/com.android.packageinstaller.InstallAppProgress (server)' ~ Consumer closed input channel or an error occurred.  events=0x8
07-18 14:33:45.143 E/InputDispatcher(178)channel '41bb4d28 com.android.packageinstaller/com.android.packageinstaller.InstallAppProgress (server)' ~ Channel is unrecoverably broken and will be disposed!
07-18 14:33:45.190 W/InputDispatcher(178)Attempted to unregister already unregistered input channel '41bb4d28 com.android.packageinstaller/com.android.packageinstaller.InstallAppProgress (server)'
07-18 14:33:45.190 I/WindowManager(178)WIN DEATH: Window{41bb4d28 com.android.packageinstaller/com.android.packageinstaller.InstallAppProgress paused=false}
07-18 14:33:45.198 I/WindowManager(178)WINDOW DIED Window{41bb4d28 com.android.packageinstaller/com.android.packageinstaller.InstallAppProgress paused=false}
07-18 14:33:47.268 D/dalvikvm(178)GC_EXPLICIT freed 338K, 20% free 22816K/28487K, paused 6ms+5ms
07-18 14:34:15.464 I/power   (178)*** set_screen_state 0
07-18 14:34:15.471 D/SurfaceFlinger(115)About to give-up screen, flinger = 0x1822918
07-18 14:34:15.596 D/NfcService(403)NFC-C OFF, disconnect

我认为重要的是这个：

com.petronicarts.stormthecastle.MainThread.run(MainThread.java:55)

看第55行，就是这样：

canvas.setMatrix(matrix);

在我的运行线程中：

    @Override
public void run() 
{
    boolean ScaleGame = true;
    //boolean SkipFrame = false;
    Bitmap screen = Bitmap.createBitmap(960, 540, Config.RGB_565);
    Canvas canvas;
    Canvas canvas2 = new Canvas(screen);
    Paint paint = new Paint();
    Matrix matrix = new Matrix();
    matrix.preScale(gamePanel.getScaleX(), gamePanel.getScaleY());
    if (gamePanel.getScaleX() == 1 && gamePanel.getScaleY() == 1)
        ScaleGame = false;
    long startTime, elapsedTime;
    startTime = System.currentTimeMillis();
    elapsedTime = System.currentTimeMillis() - startTime;

    this.gamePanel.setScreenBitmap(screen);

    while (running) {
        if(!pleaseWait) {
            canvas = null;
            // try locking the canvas for exclusive pixel editing on the surface
            try {
                canvas = this.surfaceHolder.lockCanvas();
                if (ScaleGame)
                    canvas.setMatrix(matrix);
                synchronized (surfaceHolder) {
                    startTime = System.currentTimeMillis();
                    this.gamePanel.update((float)elapsedTime);

                    canvas.drawBitmap(screen, 0, 0, paint);
                    elapsedTime = System.currentTimeMillis() - startTime;

                }
            } finally {
                if (canvas != null) {
                    surfaceHolder.unlockCanvasAndPost(canvas);
                }
            }            
        }
        else {
            synchronized (this) {
                try {
                    wait();
                } catch (Exception e) { }
            }
        }
    }
}

我不知道为什么我无法设置矩阵。似乎代码应该工作得很好。我认为这意味着我正在以一种仅适用于2.3的方式处理某些事情。

我的暂停，恢复和销毁事件如下所示：

public void pause() {
    justPause = true;
    pauseGame = true;


    SharedPreferences fileStore = this.getContext().getSharedPreferences("userData", 0);
    SharedPreferences.Editor editor = fileStore.edit();
    editor.putInt("highscore", highscore);
    editor.commit();

    AudioService.StopMusic();

}

public void resume(Context context) {
    if (gameState == 1)
        AudioService.StartMusic();
    //gold += 1000;
}

public void destroy() {
    thread.setRunning(false);


    if (thread != null)
    {
        Thread killThread = thread;
        thread = null;
        killThread.interrupt();
    }   
}

如果您有任何想法，我们将非常欢迎。感谢。

Answer 1

我看到的一个问题是在调用“canvas = this.surfaceHolder.lockCanvas（）;”之后。你只在finally块中检查null。我会把它改成这样：

if(!pleaseWait) {
    canvas = this.surfaceHolder.lockCanvas();

    if (canvas != null) {
        // try locking the canvas for exclusive pixel editing on the surface
        try {
            if (ScaleGame)
                canvas.setMatrix(matrix);
            synchronized (surfaceHolder) {
                startTime = System.currentTimeMillis();
                this.gamePanel.update((float)elapsedTime);
                canvas.drawBitmap(screen, 0, 0, paint);
                elapsedTime = System.currentTimeMillis() - startTime;
        }
        finally {
            surfaceHolder.unlockCanvasAndPost(canvas);
        }            
    }
}

如果未设置画布矩阵（当ScaleGame为false时），我还会询问是否应该运行synchronized块。我对问题或Canvas没有足够的洞察力来回答这个问题。如果答案为否，那么synchronized块应该包含在if语句中。

Answer 2

您永远不应该对UI线程持锁定，因为它可以阻止UI线程并阻止用户与您的应用程序平滑交互。 lockCanvas的文档建议与单独的绘图线程同步：

如果未返回null，lockCanvas()会在相应的unlockCanvasAndPost(Canvas)调用内部保持锁定，从而阻止SurfaceView在绘制曲面时创建，销毁或修改曲面。这比直接访问Surface更方便，因为您不需要与Callback.surfaceDestroyed中的绘图线程进行特殊同步。

Android 3.0+引入了StrictMode检查以确保开发人员不会滥用UI线程，因此您的应用在Android 2.3上运行并且在Android 4.0上运行并不奇怪。

应用程序在Android 4.0上崩溃，但不是2.3 - 奇怪的异常

2 个答案: