1

我刚开始学习动态壁纸，我做了这个小东西。

问题是我的应用程序编译没有任何问题。

当我在手机中打开它时，它会在预览中显示壁纸，但是当我单击“设置为壁纸”时，它会以某种方式崩溃，并返回前屏幕，我的壁纸变黑，但它不运行它。

我的猜测是问题出在 onDestory() 的某个地方。

public class Strips extends WallpaperService {

private StripsEngine engine;

@Override
public void onCreate() {
    super.onCreate();
    engine = new StripsEngine();
    engine.resume();

}

@Override
public void onDestroy() {
    super.onDestroy();
    engine.pause();
}

@Override
public Engine onCreateEngine() {

    return engine;
}

class StripsEngine extends Engine implements Runnable {
    private Thread t = null;
    private SurfaceHolder holder;
    private boolean clearToRun = false;
    private Paint paint = new Paint();
    private Paint paint2 = new Paint();
    private int frame;
    private float endX,endY;
    private int height, width;
    private Canvas c;


    StripsEngine() {
        holder = getSurfaceHolder();
        paint.setColor(Color.WHITE);
        paint.setStrokeWidth(30);
        paint.setAntiAlias(true);
        paint.setStrokeCap(Paint.Cap.ROUND);
        paint.setStyle(Paint.Style.STROKE);
        paint2 = paint;
        paint2.setColor(Color.BLACK);
        paint2.setStrokeWidth(40);
        frame = 0;
    }

    void drawStrips() {

    }

    public void run() {
        // TODO Auto-generated method stub
        while (clearToRun) {
            if (!holder.getSurface().isValid()) {
                continue;
            }
            height = 800;
            width = 480; 

            endX = (frame) % (width + 10);
            endY = (frame / 3) % (height + 10);

            if (endX == 0)
                paint.setARGB(255,(int)(Math.random()*255), (int)(Math.random()*255),(int)(Math.random()*255));
            if (endY ==0)
                paint.setARGB(255,(int)(Math.random()*255), (int)(Math.random()*255),(int)(Math.random()*255));


            c = holder.lockCanvas();
            c.drawLine(endX-30, endY-10, endX , endY,paint);
            c.drawLine(endX-30, endY-10, endX , endY,paint);
            holder.unlockCanvasAndPost(c);
            frame = frame +2;
            }
    }
    public void pause() {
        clearToRun = false;
        while (true) {
            try {
                t.join();
            }
            catch (InterruptedException e) {
                e.printStackTrace();    
            }
            break;
        }
        t = null;
    }

    public void resume() {
        clearToRun = true;
        t = new Thread(this);

        t.start();
    }
}

}

07-06 17:14:43.869：E/Surface(478)：出队缓冲区出错（未知错误：-19） 07-06 17:14:43.869：E/Surface(478)：dequeueBuffer 失败（没有这样的设备） 07-06 17:14:43.869: E/BaseSurfaceHolder(478): 异常锁定表面 07-06 17:14:43.869: E/BaseSurfaceHolder(478): java.lang.IllegalArgumentException 07-06 17:14:43.869: E /BaseSurfaceHolder(478): 在 android.view.Surface.lockCanvasNative(Native Method) 07-06 17:14:43.869: E/BaseSurfaceHolder(478): 在 android.view.Surface.lockCanvas(Surface.java:288) 07 -06 17:14:43.869: E/BaseSurfaceHolder(478): 在 com.android.internal.view.BaseSurfaceHolder.internalLockCanvas(BaseSurfaceHolder.java:132) 07-06 17:14:43.869: E/BaseSurfaceHolder(478):在 com.android.internal.view.BaseSurfaceHolder.lockCanvas(BaseSurfaceHolder.java:112) 07-06 17:14:43.869: E/BaseSurfaceHolder(478):在 com.mendel.strips.Strips$StripsEngine.run(Strips.java:81) 07-06 17:14:43.869: E/BaseSurfaceHolder(478): 在 java.lang.Thread.run(Thread.java:1096) 07-06 17:14:43.972: W/dalvikvm(478): threadid=15: 线程以未捕获的异常退出 (group=0x4001b188) 07-06 17:14:43.979: E/AndroidRuntime(478): 未捕获的处理程序：线程线程 8 由于未捕获的异常而退出 07-06 17:14:43.990: E/AndroidRuntime(478): java.lang.NullPointerException 07-06 17:14:43.990: E/AndroidRuntime(478): at com.mendel。 strips.Strips$StripsEngine.run(Strips.java:82) 07-06 17:14:43.990: E/AndroidRuntime(478): at java.lang.Thread.run(Thread.java:1096) 07-06 17: 14:43.999: I/dalvikvm(478): threadid=7: 对信号 3 做出反应 07-06 17:14:43.999: E/dalvikvm(478): 无法打开堆栈跟踪文件'/data/anr/traces.txt '： 没有权限Strips$StripsEngine.run(Strips.java:81) 07-06 17:14:43.869: E/BaseSurfaceHolder(478): 在 java.lang.Thread.run(Thread.java:1096) 07-06 17:14: 43.972: W/dalvikvm(478): threadid=15: 线程退出未捕获异常 (group=0x4001b188) 07-06 17:14:43.979: E/AndroidRuntime(478): 未捕获处理程序：线程 Thread-8 由于未捕获而退出异常 07-06 17:14:43.990: E/AndroidRuntime(478): java.lang.NullPointerException 07-06 17:14:43.990: E/AndroidRuntime(478): at com.mendel.strips.Strips$StripsEngine.run (Strips.java:82) 07-06 17:14:43.990: E/AndroidRuntime(478): 在 java.lang.Thread.run(Thread.java:1096) 07-06 17:14:43.999: I/dalvikvm (478): threadid=7: 响应信号 3 07-06 17:14:43.999: E/dalvikvm(478): 无法打开堆栈跟踪文件'/data/anr/traces.txt': 权限被拒绝Strips$StripsEngine.run(Strips.java:81) 07-06 17:14:43.869: E/BaseSurfaceHolder(478): 在 java.lang.Thread.run(Thread.java:1096) 07-06 17:14: 43.972: W/dalvikvm(478): threadid=15: 线程退出未捕获异常 (group=0x4001b188) 07-06 17:14:43.979: E/AndroidRuntime(478): 未捕获处理程序：线程 Thread-8 由于未捕获而退出异常 07-06 17:14:43.990: E/AndroidRuntime(478): java.lang.NullPointerException 07-06 17:14:43.990: E/AndroidRuntime(478): at com.mendel.strips.Strips$StripsEngine.run (Strips.java:82) 07-06 17:14:43.990: E/AndroidRuntime(478): 在 java.lang.Thread.run(Thread.java:1096) 07-06 17:14:43.999: I/dalvikvm (478): threadid=7: 响应信号 3 07-06 17:14:43.999: E/dalvikvm(478): 无法打开堆栈跟踪文件'/data/anr/traces.txt': 权限被拒绝81) 07-06 17:14:43.869: E/BaseSurfaceHolder(478): 在 java.lang.Thread.run(Thread.java:1096) 07-06 17:14:43.972: W/dalvikvm(478): threadid =15：线程以未捕获的异常退出（组=0x4001b188）07-06 17:14:43.979：E/AndroidRuntime（478）：未捕获的处理程序：线程 Thread-8 由于未捕获的异常而退出 07-06 17:14:43.990： E/AndroidRuntime(478): java.lang.NullPointerException 07-06 17:14:43.990: E/AndroidRuntime(478): 在 com.mendel.strips.Strips$StripsEngine.run(Strips.java:82) 07-06 17:14:43.990: E/AndroidRuntime(478): 在 java.lang.Thread.run(Thread.java:1096) 07-06 17:14:43.999: I/dalvikvm(478): threadid=7: 反应信号 3 07-06 17:14:43.999：E/dalvikvm(478)：无法打开堆栈跟踪文件“/data/anr/traces.txt”：权限被拒绝81) 07-06 17:14:43.869: E/BaseSurfaceHolder(478): 在 java.lang.Thread.run(Thread.java:1096) 07-06 17:14:43.972: W/dalvikvm(478): threadid =15：线程以未捕获的异常退出（组=0x4001b188）07-06 17:14:43.979：E/AndroidRuntime（478）：未捕获的处理程序：线程 Thread-8 由于未捕获的异常而退出 07-06 17:14:43.990： E/AndroidRuntime(478): java.lang.NullPointerException 07-06 17:14:43.990: E/AndroidRuntime(478): 在 com.mendel.strips.Strips$StripsEngine.run(Strips.java:82) 07-06 17:14:43.990: E/AndroidRuntime(478): 在 java.lang.Thread.run(Thread.java:1096) 07-06 17:14:43.999: I/dalvikvm(478): threadid=7: 反应信号 3 07-06 17:14:43.999：E/dalvikvm(478)：无法打开堆栈跟踪文件“/data/anr/traces.txt”：权限被拒绝java:1096) 07-06 17:14:43.972: W/dalvikvm(478): threadid=15: 线程以未捕获的异常退出 (group=0x4001b188) 07-06 17:14:43.979: E/AndroidRuntime(478):未捕获的处理程序：线程 Thread-8 由于未捕获的异常而退出 07-06 17:14:43.990: E/AndroidRuntime(478): java.lang.NullPointerException 07-06 17:14:43.990: E/AndroidRuntime(478): at com.mendel.strips.Strips$StripsEngine.run(Strips.java:82) 07-06 17:14:43.990: E/AndroidRuntime(478): at java.lang.Thread.run(Thread.java:1096) 07 -06 17:14:43.999: I/dalvikvm(478): threadid=7: 响应信号 3 07-06 17:14:43.999: E/dalvikvm(478): 无法打开堆栈跟踪文件'/data/anr /traces.txt'：权限被拒绝java:1096) 07-06 17:14:43.972: W/dalvikvm(478): threadid=15: 线程以未捕获的异常退出 (group=0x4001b188) 07-06 17:14:43.979: E/AndroidRuntime(478):未捕获的处理程序：线程 Thread-8 由于未捕获的异常而退出 07-06 17:14:43.990: E/AndroidRuntime(478): java.lang.NullPointerException 07-06 17:14:43.990: E/AndroidRuntime(478): at com.mendel.strips.Strips$StripsEngine.run(Strips.java:82) 07-06 17:14:43.990: E/AndroidRuntime(478): at java.lang.Thread.run(Thread.java:1096) 07 -06 17:14:43.999: I/dalvikvm(478): threadid=7: 响应信号 3 07-06 17:14:43.999: E/dalvikvm(478): 无法打开堆栈跟踪文件'/data/anr /traces.txt'：权限被拒绝未捕获的处理程序：线程 Thread-8 由于未捕获的异常而退出 07-06 17:14:43.990: E/AndroidRuntime(478): java.lang.NullPointerException 07-06 17:14:43.990: E/AndroidRuntime(478): at com.mendel.strips.Strips$StripsEngine.run(Strips.java:82) 07-06 17:14:43.990: E/AndroidRuntime(478): at java.lang.Thread.run(Thread.java:1096) 07 -06 17:14:43.999: I/dalvikvm(478): threadid=7: 响应信号 3 07-06 17:14:43.999: E/dalvikvm(478): 无法打开堆栈跟踪文件'/data/anr /traces.txt'：权限被拒绝未捕获的处理程序：线程 Thread-8 由于未捕获的异常而退出 07-06 17:14:43.990: E/AndroidRuntime(478): java.lang.NullPointerException 07-06 17:14:43.990: E/AndroidRuntime(478): at com.mendel.strips.Strips$StripsEngine.run(Strips.java:82) 07-06 17:14:43.990: E/AndroidRuntime(478): at java.lang.Thread.run(Thread.java:1096) 07 -06 17:14:43.999: I/dalvikvm(478): threadid=7: 响应信号 3 07-06 17:14:43.999: E/dalvikvm(478): 无法打开堆栈跟踪文件'/data/anr /traces.txt'：权限被拒绝运行（Thread.java:1096）07-06 17:14:43.999：I/dalvikvm（478）：threadid=7：对信号 3 做出反应 07-06 17:14:43.999：E/dalvikvm（478）：无法打开堆栈跟踪文件'/data/anr/traces.txt'：权限被拒绝运行（Thread.java:1096）07-06 17:14:43.999：I/dalvikvm（478）：threadid=7：对信号 3 做出反应 07-06 17:14:43.999：E/dalvikvm（478）：无法打开堆栈跟踪文件'/data/anr/traces.txt'：权限被拒绝

4

2 回答 2

1

这可能是因为您请求的画布holder.lockCanvas()尚不可用，所以它为空，并且您得到 NullPointerException。

参见文档lockCanvas()

返回的 Canvas 可用于绘制到表面的位图中。如果尚未创建曲面或无法编辑曲面，则返回 null。您通常需要实现 Callback.surfaceCreated 以了解 Surface 何时可用。

更新：

根据您之前调用的 isValid() 的文档 - Does this object hold a valid surface? Returns true if it holds a physical surface, so lockCanvas() will succeed. Otherwise returns false.

此时画布不应为空。但我发现这个，似乎是Android的一个错误：

http://code.google.com/p/android/issues/detail?id=19245

因此，您可能必须尝试该Callback.surfaceCreated方法，或者，如果没有其他方法，请尝试像海报（谁删除了帖子）那样的超时，建议，但这确实是您应该避免的事情，因为它不可靠且混乱。

于 2012-07-06T17:27:03.853 回答
0

我得到了答案！

我查看了立方体动态壁纸示例并复制了结构，这里是代码：

public class Strips extends WallpaperService {

private final Handler mHandler = new Handler();   
@Override
public void onCreate() {
    super.onCreate();

}

@Override
public void onDestroy() {
    super.onDestroy();
}

@Override
public Engine onCreateEngine() {

    return new StripsEngine();
}

class StripsEngine extends Engine   {
    private Thread t = null;
;
    private boolean clearToRun = false;
    private Paint paint = new Paint();
    private Paint paint2 = new Paint();
    private int frame;
    private float endX,endY;
    private int height, width;
    private Canvas c;

    private final Runnable mDrawStrip = new Runnable() {
        public void run() {
            drawFrame();
        }
    };


    StripsEngine() {
        paint.setColor(Color.WHITE);
        paint.setStrokeWidth(30);
        paint.setAntiAlias(true);
        paint.setStrokeCap(Paint.Cap.ROUND);
        paint.setStyle(Paint.Style.STROKE);
        paint2 = paint;
        paint2.setColor(Color.BLACK);
        paint2.setStrokeWidth(40);
        frame = 0;
    }

     @Override
        public void onDestroy() {
            super.onDestroy();
            mHandler.removeCallbacks(mDrawStrip);
        }

     @Override
        public void onSurfaceCreated(SurfaceHolder holder) {
            super.onSurfaceCreated(holder);
        }

     @Override
        public void onSurfaceDestroyed(SurfaceHolder holder) {
            super.onSurfaceDestroyed(holder);
            clearToRun = false;
            mHandler.removeCallbacks(mDrawStrip);
        }


     @Override
        public void onVisibilityChanged(boolean visible) {
            clearToRun = visible;
            if (visible) {
                drawFrame();
            } else {
                mHandler.removeCallbacks(mDrawStrip);
            }
        }


    public void drawFrame() {
        // TODO Auto-generated method stub
     final SurfaceHolder holder = getSurfaceHolder();
       Canvas c = null;
       try {
           c = holder.lockCanvas();
           if (c != null) {
               // draw something
            height = 800;
            width = 480; 

            endX = (frame) % (width + 10);
            endY = (frame / 3) % (height + 10);


            if (endX == 0)
                paint.setARGB(255,(int)(Math.random()*255), (int)(Math.random()*255),(int)(Math.random()*255));
            if (endY ==0)
                paint.setARGB(255,(int)(Math.random()*255), (int)(Math.random()*255),(int)(Math.random()*255));

            c.drawLine(endX-30, endY-10, endX , endY,paint);
            frame = frame +2;
           }
       } finally {
           if (c != null) holder.unlockCanvasAndPost(c);
       }
         mHandler.removeCallbacks(mDrawStrip);
            if (clearToRun) {
                mHandler.postDelayed(mDrawStrip, 1000 / 25);
            }
    }

}

}
于 2012-07-06T18:30:05.163 回答