android gesturedetector能识别旋转手势吗

是的，Android的GestureDetector可以识别旋转手势。你可以通过实现OnGestureListener接口并重写onFling()方法来检测旋转手势。以下是一个简单的示例：

import android.content.Context;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Toast;

public class RotationGestureDetector implements GestureDetector.OnGestureListener {

    private GestureDetector gestureDetector;

    public RotationGestureDetector(Context context) {
        gestureDetector = new GestureDetector(context, this);
    }

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
        float angle = getAngle(e1, e2);
        if (Math.abs(angle) > 10) { // 设置一个阈值，可以根据需要调整
            Toast.makeText(gestureDetector.getContext(), "旋转角度: " + angle, Toast.LENGTH_SHORT).show();
            return true;
        }
        return false;
    }

    private float getAngle(MotionEvent e1, MotionEvent e2) {
        float centerX1 = (e1.getX() + e1.getX() / 2);
        float centerY1 = (e1.getY() + e1.getY() / 2);
        float centerX2 = (e2.getX() + e2.getX() / 2);
        float centerY2 = (e2.getY() + e2.getY() / 2);

        float distanceX = centerX2 - centerX1;
        float distanceY = centerY2 - centerY1;

        return (float) Math.toDegrees(Math.atan2(distanceY, distanceX));
    }

    @Override
    public void onShowPress(MotionEvent e) {
    }

    @Override
    public boolean onSingleTapConfirmed(MotionEvent e) {
        return false;
    }

    @Override
    public boolean onDoubleTap(MotionEvent e) {
        return false;
    }

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

    @Override
    public void onLongPress(MotionEvent e) {
    }

    public void setOnGestureListener(View view) {
        view.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                return gestureDetector.onTouchEvent(event);
            }
        });
    }
}

在你的Activity中，你可以这样使用这个类：

RotationGestureDetector rotationGestureDetector = new RotationGestureDetector(this);
rotationGestureDetector.setOnGestureListener(findViewById(R.id.your_view));

这样，当用户在指定视图上执行旋转手势时，应用程序会检测到旋转角度并显示一个Toast消息。