android 用java编写一个悬浮窗图片按钮，id为cat，点击cat 环绕展开 a b c 三个 image，自动吸附边缘时收回 a b c三个image ,并改变cat图片

好的，我可以为您提供一份示例代码。但是需要注意的是，悬浮窗功能需要使用android.permission.SYSTEM_ALERT_WINDOW权限，而且自动吸附边缘的实现需要使用WindowManager.LayoutParams的相关方法，这些方法可能不太容易理解，需要您具备一定的Android开发经验。

以下是示例代码：

public class FloatWindowActivity extends Activity {

    private WindowManager mWindowManager;
    private View mFloatView;
    private ImageView mCatView;
    private ImageView mAView;
    private ImageView mBView;
    private ImageView mCView;

    private boolean mExpanded = false;
    private boolean mMoving = false;
    private float mStartX, mStartY;
    private float mLastX, mLastY;
    private float mScreenWidth, mScreenHeight;
    private float mImageSize;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_float_window);

        mWindowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
        mScreenWidth = mWindowManager.getDefaultDisplay().getWidth();
        mScreenHeight = mWindowManager.getDefaultDisplay().getHeight();
        mImageSize = getResources().getDimension(R.dimen.image_size);

        mFloatView = LayoutInflater.from(this).inflate(R.layout.view_float_window, null);
        mCatView = (ImageView) mFloatView.findViewById(R.id.cat);
        mAView = (ImageView) mFloatView.findViewById(R.id.a);
        mBView = (ImageView) mFloatView.findViewById(R.id.b);
        mCView = (ImageView) mFloatView.findViewById(R.id.c);

        mCatView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (mExpanded) {
                    collapse();
                } else {
                    expand();
                }
            }
        });

        mCatView.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                switch (event.getAction()) {
                    case MotionEvent.ACTION_DOWN:
                        mMoving = false;
                        mStartX = event.getRawX();
                        mStartY = event.getRawY();
                        mLastX = mStartX;
                        mLastY = mStartY;
                        break;
                    case MotionEvent.ACTION_MOVE:
                        float x = event.getRawX();
                        float y = event.getRawY();
                        float dx = x - mLastX;
                        float dy = y - mLastY;
                        if (Math.abs(dx) > 10 || Math.abs(dy) > 10) {
                            mMoving = true;
                            updatePosition(dx, dy);
                            mLastX = x;
                            mLastY = y;
                        }
                        break;
                    case MotionEvent.ACTION_UP:
                        if (!mMoving) {
                            v.performClick();
                        } else {
                            autoAttach();
                        }
                        break;
                }
                return true;
            }
        });

        WindowManager.LayoutParams params = new WindowManager.LayoutParams();
        params.type = WindowManager.LayoutParams.TYPE_SYSTEM_ALERT;
        params.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
                | WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN
                | WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS;
        params.format = PixelFormat.TRANSLUCENT;
        params.gravity = Gravity.TOP | Gravity.LEFT;
        params.width = WindowManager.LayoutParams.WRAP_CONTENT;
        params.height = WindowManager.LayoutParams.WRAP_CONTENT;
        params.x = 0;
        params.y = 0;

        mWindowManager.addView(mFloatView, params);
    }

    private void updatePosition(float dx, float dy) {
        WindowManager.LayoutParams params = (WindowManager.LayoutParams) mFloatView.getLayoutParams();
        params.x += dx;
        params.y += dy;
        params.x = Math.max(0, Math.min((int) (mScreenWidth - mImageSize), params.x));
        params.y = Math.max(0, Math.min((int) (mScreenHeight - mImageSize), params.y));
        mWindowManager.updateViewLayout(mFloatView, params);
    }

    private void expand() {
        mExpanded = true;
        mCatView.setImageResource(R.drawable.cat2);

        mAView.setVisibility(View.VISIBLE);
        mBView.setVisibility(View.VISIBLE);
        mCView.setVisibility(View.VISIBLE);

        float degree = (float) (Math.PI / 4);
        float radius = mImageSize * 2;

        updatePosition(0, -radius);

        ObjectAnimator.ofFloat(mAView, "translationX", 0, radius * (float) Math.sin(degree))
                .setDuration(300).start();
        ObjectAnimator.ofFloat(mAView, "translationY", 0, -radius * (float) Math.cos(degree))
                .setDuration(300).start();
        ObjectAnimator.ofFloat(mBView, "translationX", 0, radius * (float) Math.cos(degree))
                .setDuration(300).start();
        ObjectAnimator.ofFloat(mBView, "translationY", 0, -radius * (float) Math.sin(degree))
                .setDuration(300).start();
        ObjectAnimator.ofFloat(mCView, "translationX", 0, radius)
                .setDuration(300).start();
    }

    private void collapse() {
        mExpanded = false;
        mCatView.setImageResource(R.drawable.cat1);

        ObjectAnimator.ofFloat(mAView, "translationX", mAView.getTranslationX(), 0)
                .setDuration(300).start();
        ObjectAnimator.ofFloat(mAView, "translationY", mAView.getTranslationY(), 0)
                .setDuration(300).start();
        ObjectAnimator.ofFloat(mBView, "translationX", mBView.getTranslationX(), 0)
                .setDuration(300).start();
        ObjectAnimator.ofFloat(mBView, "translationY", mBView.getTranslationY(), 0)
                .setDuration(300).start();
        ObjectAnimator.ofFloat(mCView, "translationX", mCView.getTranslationX(), 0)
                .setDuration(300).start();

        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                mAView.setVisibility(View.GONE);
                mBView.setVisibility(View.GONE);
                mCView.setVisibility(View.GONE);
            }
        }, 300);
    }

    private void autoAttach() {
        WindowManager.LayoutParams params = (WindowManager.LayoutParams) mFloatView.getLayoutParams();
        int x = params.x;
        int y = params.y;
        int centerX = (int) (x + mImageSize / 2);
        int centerY = (int) (y + mImageSize / 2);
        int left = 0, top = 0, right = (int) mScreenWidth, bottom = (int) mScreenHeight;
        if (centerX < mScreenWidth / 2) {
            right = (int) (mScreenWidth / 2);
        } else {
            left = (int) (mScreenWidth / 2);
        }
        if (centerY < mScreenHeight / 2) {
            bottom = (int) (mScreenHeight / 2);
        } else {
            top = (int) (mScreenHeight / 2);
        }
        if (x < left) {
            ObjectAnimator.ofFloat(mFloatView, "translationX", x - left, 0)
                    .setDuration(300).start();
            params.x = left;
        } else if (x + mImageSize > right) {
            ObjectAnimator.ofFloat(mFloatView, "translationX", x + mImageSize - right, 0)
                    .setDuration(300).start();
            params.x = right - (int) mImageSize;
        }
        if (y < top) {
            ObjectAnimator.ofFloat(mFloatView, "translationY", y - top, 0)
                    .setDuration(300).start();
            params.y = top;
        } else if (y + mImageSize > bottom) {
            ObjectAnimator.ofFloat(mFloatView, "translationY", y + mImageSize - bottom, 0)
                    .setDuration(300).start();
            params.y = bottom - (int) mImageSize;
        }
        mWindowManager.updateViewLayout(mFloatView, params);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (mFloatView != null) {
            mWindowManager.removeView(mFloatView);
        }
    }
}

布局文件view_float_window.xml如下：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">

    <ImageView
        android:id="@+id/cat"
        android:layout_width="@dimen/image_size"
        android:layout_height="@dimen/image_size"
        android:src="@drawable/cat1"/>

    <ImageView
        android:id="@+id/a"
        android:layout_width="@dimen/image_size"
        android:layout_height="@dimen/image_size"
        android:src="@drawable/a"
        android:visibility="gone"/>

    <ImageView
        android:id="@+id/b"
        android:layout_width="@dimen/image_size"
        android:layout_height="@dimen/image_size"
        android:src="@drawable/b"
        android:visibility="gone"/>

    <ImageView
        android:id="@+id/c"
        android:layout_width="@dimen/image_size"
        android:layout_height="@dimen/image_size"
        android:src="@drawable/c"
        android:visibility="gone"/>

</RelativeLayout>

其中，@dimen/image_size定义了图片的大小，可以根据需要进行修改。同时，@drawable/cat1、@drawable/cat2、@drawable/a、@drawable/b、@drawable/c是五张图片资源，需要提前准备好放在res/drawable目录下。

希望这份代码对您有所帮助，若有疑问请随时提出。