1、直接继承ViewGroup类，onMeasure测量子控件，onLayout第一个子控件放在边角，其他的子控件根据弧度计算其位置来进行layout。

2、动画效果：第一个按钮的旋转动画 RotateAnimation，其他的控件TranslateAnimation和RotateAnimation两个动画，点击ScaleAnimation动画和AlphaAnimation动画 ，设置好延迟的时间间隔就可以看到效果了。

import android.content.Context;import android.content.res.TypedArray;import android.util.AttributeSet;import android.util.Log;import android.util.TypedValue;import android.view.View;import android.view.View.OnClickListener;import android.view.ViewGroup;import android.view.animation.Animation;import android.view.animation.Animation.AnimationListener;import android.view.animation.AlphaAnimation;import android.view.animation.AnimationSet;import android.view.animation.OvershootInterpolator;import android.view.animation.RotateAnimation;import android.view.animation.ScaleAnimation;import android.view.animation.TranslateAnimation;/** * @author zhy */public class ArcMenu extends ViewGroup implements OnClickListener{    private static final String TAG = "ArcMenu";    /**     * 菜单的显示位置     */    private Position mPosition = Position.LEFT_TOP;    /**     * 菜单显示的半径，默认100dp     */    private int mRadius = 100;    /**     * 用户点击的按钮     */    private View mButton;    /**     * 当前ArcMenu的状态     */    private Status mCurrentStatus = Status.CLOSE;    /**     * 回调接口     */    private OnMenuItemClickListener onMenuItemClickListener;    /**     * 状态的枚举类     *      * @author zhy     *      */    public enum Status    {        OPEN, CLOSE    }    /**     * 设置菜单现实的位置，四选1，默认右下     *      * @author zhy     */    public enum Position    {        LEFT_TOP, RIGHT_TOP, RIGHT_BOTTOM, LEFT_BOTTOM;    }    public interface OnMenuItemClickListener    {        void onClick(View view, int pos);    }    public ArcMenu(Context context)    {        this(context, null);    }    public ArcMenu(Context context, AttributeSet attrs)    {        this(context, attrs, 0);    }    /**     * 初始化属性     *      * @param context     * @param attrs     * @param defStyle     */    public ArcMenu(Context context, AttributeSet attrs, int defStyle)    {        super(context, attrs, defStyle);        // dp convert to px        mRadius = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,                mRadius, getResources().getDisplayMetrics());        TypedArray a = context.getTheme().obtainStyledAttributes(attrs,                R.styleable.ArcMenu, defStyle, 0);        int n = a.getIndexCount();        for (int i = 0; i < n; i++)        {            int attr = a.getIndex(i);            switch (attr)            {            case R.styleable.ArcMenu_position:                int val = a.getInt(attr, 0);                switch (val)                {                case 0:                    mPosition = Position.LEFT_TOP;                    break;                case 1:                    mPosition = Position.RIGHT_TOP;                    break;                case 2:                    mPosition = Position.RIGHT_BOTTOM;                    break;                case 3:                    mPosition = Position.LEFT_BOTTOM;                    break;                }                break;            case R.styleable.ArcMenu_radius:                // dp convert to px                mRadius = a.getDimensionPixelSize(attr, (int) TypedValue                        .applyDimension(TypedValue.COMPLEX_UNIT_DIP, 100f,                                getResources().getDisplayMetrics()));                break;            }        }        a.recycle();    }    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)    {        int count = getChildCount();        for (int i = 0; i < count; i++)        {            // mesure child            getChildAt(i).measure(MeasureSpec.UNSPECIFIED,                    MeasureSpec.UNSPECIFIED);        }        super.onMeasure(widthMeasureSpec, heightMeasureSpec);    }    @Override    protected void onLayout(boolean changed, int l, int t, int r, int b)    {        if (changed)        {            layoutButton();            int count = getChildCount();            /**             * 设置所有孩子的位置 例如(第一个为按钮)： 左上时，从左到右 ] 第2个：mRadius(sin0 , cos0)             * 第3个：mRadius(sina ,cosa) 注：[a = Math.PI / 2 * (cCount - 1)]             * 第4个：mRadius(sin2a ,cos2a) 第5个：mRadius(sin3a , cos3a) ...             */            for (int i = 0; i < count - 1; i++)            {                View child = getChildAt(i + 1);                child.setVisibility(View.GONE);                int cl = (int) (mRadius * Math.sin(Math.PI / 2 / (count - 2)                        * i));                int ct = (int) (mRadius * Math.cos(Math.PI / 2 / (count - 2)                        * i));                // childview width                int cWidth = child.getMeasuredWidth();                // childview height                int cHeight = child.getMeasuredHeight();                // 右上，右下                if (mPosition == Position.LEFT_BOTTOM                        || mPosition == Position.RIGHT_BOTTOM)                {                    ct = getMeasuredHeight() - cHeight - ct;                }                // 右上，右下                if (mPosition == Position.RIGHT_TOP                        || mPosition == Position.RIGHT_BOTTOM)                {                    cl = getMeasuredWidth() - cWidth - cl;                }                Log.e(TAG, cl + " , " + ct);                child.layout(cl, ct, cl + cWidth, ct + cHeight);            }        }    }    /**     * 第一个子元素为按钮，为按钮布局且初始化点击事件     */    private void layoutButton()    {        View cButton = getChildAt(0);        cButton.setOnClickListener(this);        int l = 0;        int t = 0;        int width = cButton.getMeasuredWidth();        int height = cButton.getMeasuredHeight();        switch (mPosition)        {        case LEFT_TOP:            l = 0;            t = 0;            break;        case LEFT_BOTTOM:            l = 0;            t = getMeasuredHeight() - height;            break;        case RIGHT_TOP:            l = getMeasuredWidth() - width;            t = 0;            break;        case RIGHT_BOTTOM:            l = getMeasuredWidth() - width;            t = getMeasuredHeight() - height;            break;        }        Log.e(TAG, l + " , " + t + " , " + (l + width) + " , " + (t + height));        cButton.layout(l, t, l + width, t + height);    }    /**     * 为按钮添加点击事件     */    @Override    public void onClick(View v)    {        mButton = findViewById(R.id.id_button);        if (mButton == null)        {            mButton = getChildAt(0);        }        rotateView(mButton, 0f, 270f, 300);        toggleMenu(300);    }    /**     * 按钮的旋转动画     *      * @param view     * @param fromDegrees     * @param toDegrees     * @param durationMillis     */    public static void rotateView(View view, float fromDegrees,            float toDegrees, int durationMillis)    {        RotateAnimation rotate = new RotateAnimation(fromDegrees, toDegrees,                Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF,                0.5f);        rotate.setDuration(durationMillis);        rotate.setFillAfter(true);        view.startAnimation(rotate);    }    public void toggleMenu(int durationMillis)    {        int count = getChildCount();        for (int i = 0; i < count - 1; i++)        {            final View childView = getChildAt(i + 1);            childView.setVisibility(View.VISIBLE);            int xflag = 1;            int yflag = 1;            if (mPosition == Position.LEFT_TOP                    || mPosition == Position.LEFT_BOTTOM)                xflag = -1;            if (mPosition == Position.LEFT_TOP                    || mPosition == Position.RIGHT_TOP)                yflag = -1;            // child left            int cl = (int) (mRadius * Math.sin(Math.PI / 2 / (count - 2) * i));            // child top            int ct = (int) (mRadius * Math.cos(Math.PI / 2 / (count - 2) * i));            AnimationSet animset = new AnimationSet(true);            Animation animation = null;            if (mCurrentStatus == Status.CLOSE)            {
    // to open                animset.setInterpolator(new OvershootInterpolator(2F));                animation = new TranslateAnimation(xflag * cl, 0, yflag * ct, 0);                childView.setClickable(true);                childView.setFocusable(true);            } else            {
    // to close                animation = new TranslateAnimation(0f, xflag * cl, 0f, yflag                        * ct);                childView.setClickable(false);                childView.setFocusable(false);            }            animation.setAnimationListener(new AnimationListener()            {                public void onAnimationStart(Animation animation)                {                }                public void onAnimationRepeat(Animation animation)                {                }                public void onAnimationEnd(Animation animation)                {                    if (mCurrentStatus == Status.CLOSE)                        childView.setVisibility(View.GONE);                }            });            animation.setFillAfter(true);            animation.setDuration(durationMillis);            // 为动画设置一个开始延迟时间，纯属好看，可以不设            animation.setStartOffset((i * 100) / (count - 1));            RotateAnimation rotate = new RotateAnimation(0, 720,                    Animation.RELATIVE_TO_SELF, 0.5f,                    Animation.RELATIVE_TO_SELF, 0.5f);            rotate.setDuration(durationMillis);            rotate.setFillAfter(true);            animset.addAnimation(rotate);            animset.addAnimation(animation);            childView.startAnimation(animset);            final int index = i + 1;            childView.setOnClickListener(new View.OnClickListener()            {                @Override                public void onClick(View v)                {                    if (onMenuItemClickListener != null)                        onMenuItemClickListener.onClick(childView, index - 1);                    menuItemAnin(index - 1);                    changeStatus();                                    }            });        }        changeStatus();        Log.e(TAG, mCurrentStatus.name() +"");    }    private void changeStatus()    {        mCurrentStatus = (mCurrentStatus == Status.CLOSE ? Status.OPEN                : Status.CLOSE);    }    /**     * 开始菜单动画，点击的MenuItem放大消失，其他的缩小消失     * @param item     */    private void menuItemAnin(int item)    {        for (int i = 0; i < getChildCount() - 1; i++)        {            View childView = getChildAt(i + 1);            if (i == item)            {                childView.startAnimation(scaleBigAnim(300));            } else            {                childView.startAnimation(scaleSmallAnim(300));            }            childView.setClickable(false);            childView.setFocusable(false);        }    }        /**     * 缩小消失     * @param durationMillis     * @return     */    private Animation scaleSmallAnim(int durationMillis)    {        Animation anim = new ScaleAnimation(1.0f, 0f, 1.0f, 0f,                Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF,                0.5f);        anim.setDuration(durationMillis);        anim.setFillAfter(true);        return anim;    }    /**     * 放大，透明度降低     * @param durationMillis     * @return     */    private Animation scaleBigAnim(int durationMillis)    {        AnimationSet animationset = new AnimationSet(true);        Animation anim = new ScaleAnimation(1.0f, 4.0f, 1.0f, 4.0f,                Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF,                0.5f);        Animation alphaAnimation = new AlphaAnimation(1, 0);        animationset.addAnimation(anim);        animationset.addAnimation(alphaAnimation);        animationset.setDuration(durationMillis);        animationset.setFillAfter(true);        return animationset;    }    public Position getmPosition()    {        return mPosition;    }    public void setmPosition(Position mPosition)    {        this.mPosition = mPosition;    }    public int getmRadius()    {        return mRadius;    }    public void setmRadius(int mRadius)    {        this.mRadius = mRadius;    }    public Status getmCurrentStatus()    {        return mCurrentStatus;    }    public void setmCurrentStatus(Status mCurrentStatus)    {        this.mCurrentStatus = mCurrentStatus;    }    public OnMenuItemClickListener getOnMenuItemClickListener()    {        return onMenuItemClickListener;    }    public void setOnMenuItemClickListener(            OnMenuItemClickListener onMenuItemClickListener)    {        this.onMenuItemClickListener = onMenuItemClickListener;    }}