如何创建一个surfaceview

要创建一个SurfaceView，你需要创建一个自定义视图类，并在其中添加SurfaceHolder。以下是创建SurfaceView的步骤：

1.创建一个继承自SurfaceView的自定义视图类：

public class MySurfaceView extends SurfaceView {

    public MySurfaceView(Context context) {
        super(context);
    }

    public MySurfaceView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public MySurfaceView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }
}

2.在自定义视图类中添加SurfaceHolder变量：

private SurfaceHolder surfaceHolder;

3.在构造函数中实例化SurfaceHolder：

public MySurfaceView(Context context) {
    super(context);
    surfaceHolder = getHolder();
}

4.实现SurfaceHolder.Callback接口：

public class MySurfaceView extends SurfaceView implements SurfaceHolder.Callback {

    public MySurfaceView(Context context) {
        super(context);
        surfaceHolder = getHolder();
        surfaceHolder.addCallback(this);
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {

    }

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

    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {

    }
}

5.在surfaceCreated方法中开启线程：

@Override
public void surfaceCreated(SurfaceHolder holder) {
    new MyThread().start();
}

private class MyThread extends Thread {
    @Override
    public void run() {
        while (true) {
            Canvas canvas = surfaceHolder.lockCanvas();
            // 进行绘制操作
            surfaceHolder.unlockCanvasAndPost(canvas);
        }
    }
}

6.在自定义视图中绘制图形

@Override
public void run() {
    while (true) {
        Canvas canvas = surfaceHolder.lockCanvas();
        Paint paint = new Paint();
        canvas.drawCircle(100, 100, 50, paint);
        surfaceHolder.unlockCanvasAndPost(canvas);
    }
}

这样，你就创建了一个SurfaceView，并且在其中绘制了一个圆。