在SurfaceView下画图的片段

在SurfaceView上画图的片段
        mPaint = new Paint();    
        mPaint.setColor(Color.RED);// 画笔为绿色     
        mPaint.setStrokeWidth(2); // 设置画笔粗细

byte[] buffer = new byte[300];
try {
File f = new File("/sdcard/xiangshuibaihe.mp3");
        FileInputStream input;
input = new FileInputStream(f);
        BufferedInputStream inBuff=new BufferedInputStream(input);
        while(inBuff.read(buffer) != -1 && showYN==1)
        {
        //sleep(1000);
            Canvas canvas = mysv.getHolder().lockCanvas(  
                    new Rect(0, 0, 0 + buffer.length, mysv.getHeight()));// 关键:获取画布  
            canvas.drawColor(Color.BLACK);// 清除背景
            for(int i=0; i<buffer.length; i++)
            {
            int y = buffer[i];
            int x = i;
            canvas.drawLine(x, 0, x, y, mPaint);  
            }
mysv.getHolder().unlockCanvasAndPost(canvas);// 解锁画布，提交画好的图像
        }

} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} */