自定义GridView实现长按拖动切换item的位置

这几天我们要求实现仿支付宝首页全部应用管理功能(长按gridview图标拖动切换item的位置),我在网上找到了自定义的代码略加改动实现了效果,现在我将代码贴出来，由于我也是很少接触自定义的东西很多东西也没有弄明白供大家参考，欢迎大家批评指正。

使用自定义的方式这里需要使用的适配器是有限制的，这是实现的基础的Adapter然后在设置适配器的时候需要继承BaseAdapter再实现

DragGridBaseAdapter接口
public interface DragGridBaseAdapter {    /**     * 重新排列数据     * @param oldPosition     * @param newPosition     */    public void reorderItems(int oldPosition, int newPosition);    /**     * 设置某个item隐藏     * @param hidePosition     */    public void setHideItem(int hidePosition);    /**     * 删除某个item     * @param removePosition     */    public void removeItem(int removePosition);}下面我就贴出我写的适配器的代码,仅供大家参考
class MeAppAdapter extends BaseAdapter implements DragGridBaseAdapter {    List<HashMap<String, Object>> melist;    PRivate LayoutInflater mInflater;    boolean isShowIcans;    private int mHidePosition=-1;    public MeAppAdapter(List<HashMap<String, Object>> melist) {        this.melist = melist;        mInflater = LayoutInflater.from(MoreServerActivity.this);    }    public void setIsShowIcans(boolean isShowIcans) {        this.isShowIcans = isShowIcans;        notifyDataSetChanged();    }    @Override    public int getCount() {        return melist != null ? melist.size() : 0;    }    @Override    public Object getItem(int position) {        return melist.get(position);    }    @Override    public long getItemId(int position) {        return position;    }    @Override    public View getView(final int position, View convertView, ViewGroup viewGroup) {        convertView = mInflater.inflate(R.layout.me_moreapp, null);        ImageView me_appimg = (ImageView) convertView.findViewById(R.id.me_appimg);        ImageView me_app_charge = (ImageView) convertView.findViewById(R.id.me_app_charge);        TextView me_app_text = (TextView) convertView.findViewById(R.id.me_app_text);        AutoRelativeLayout me_app_item = (AutoRelativeLayout) convertView.findViewById(R.id.me_app_item);        me_appimg.setImageResource(R.mipmap.parknavi);        me_app_text.setText((CharSequence) melist.get(position).get("item_text"));        me_app_charge.setVisibility(isShowIcans ? View.VISIBLE : View.GONE);        me_app_charge.setImageResource(R.mipmap.reduce);        if (isShowIcans) {            me_app_item.setBackgroundResource(R.drawable.gridview_line);        } else {            me_app_item.setBackgroundResource(R.drawable.gridview_noline);        }        me_app_charge.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                parklist.add(melist.get(position));                melist.remove(position);                meAppAdapter.notifyDataSetChanged();                moreParkAppAdapter.notifyDataSetChanged();            }        });        if (position == mHidePosition) {            convertView.setVisibility(View.INVISIBLE);        }        return convertView;    }    @Override    public void reorderItems(int oldPosition, int newPosition) {        HashMap<String, Object> temp = melist.get(oldPosition);        if (oldPosition < newPosition) {            for (int i = oldPosition; i < newPosition; i++) {                Collections.swap(melist, i, i + 1);            }        } else if (oldPosition > newPosition) {            for (int i = oldPosition; i > newPosition; i--) {                Collections.swap(melist, i, i - 1);            }        }        melist.set(newPosition, temp);    }    @Override    public void setHideItem(int hidePosition) {        this.mHidePosition = hidePosition;        notifyDataSetChanged();    }    @Override    public void removeItem(int removePosition) {        melist.remove(removePosition);        notifyDataSetChanged();    }}
其他都非常简单，这是自定义GridView的核心代码
public class DragGridView extends GridView {    /**     * DragGridView的item长按响应的时间， 默认是1000毫秒，也可以自行设置     */    private long dragResponseMS = 1000;    /**     * 是否可以拖拽，默认不可以     */    private boolean isDrag = false;    private int mDownX;    private int mDownY;    private int moveX;    private int moveY;    /**     * 正在拖拽的position     */    private int mDragPosition;    /**     * 刚开始拖拽的item对应的View     */    private View mStartDragItemView = null;    /**     * 用于拖拽的镜像，这里直接用一个ImageView     */    private ImageView mDragImageView;    /**     * 震动器     */    private Vibrator mVibrator;    private WindowManager mWindowManager;    /**     * item镜像的布局参数     */    private WindowManager.LayoutParams mWindowLayoutParams;    /**     * 我们拖拽的item对应的Bitmap     */    private Bitmap mDragBitmap;    /**     * 按下的点到所在item的上边缘的距离     */    private int mPoint2ItemTop;    /**     * 按下的点到所在item的左边缘的距离     */    private int mPoint2ItemLeft;    /**     * DragGridView距离屏幕顶部的偏移量     */    private int mOffset2Top;    /**     * DragGridView距离屏幕左边的偏移量     */    private int mOffset2Left;    /**     * 状态栏的高度     */    private int mStatusHeight;    /**     * DragGridView自动向下滚动的边界值     */    private int mDownScrollBorder;    /**     * DragGridView自动向上滚动的边界值     */    private int mUpScrollBorder;    /**     * DragGridView自动滚动的速度     */    private static final int speed = 20;    /**     * item的移动动画是否结束     */    private boolean mAnimationEnd = true;    private DragGridBaseAdapter mDragAdapter;    /**     * GridView的列数     */    private int mNumColumns;    /**     * 当GridView的numColumns设置为AUTO_FIT，我们需要计算GirdView具体的列数     */    private int mColumnWidth;    /**     * GridView是否设置了numColumns为具体的数字     */    private boolean mNumColumnsSet;    private int mHorizontalSpacing;    private int mVerticalSpacing;    public DragGridView(Context context) {        this(context, null);    }    public DragGridView(Context context, AttributeSet attrs) {        this(context, attrs, 0);    }    public DragGridView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        mVibrator = (Vibrator) context.getSystemService(Context.VIBRATOR_SERVICE);        mWindowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);        mStatusHeight = getStatusHeight(context); //获取状态栏的高度        if (!mNumColumnsSet) {            mNumColumns = AUTO_FIT;        }    }    /**     * 删除item的动画效果     *     * @param position     */    public void removeItemAnimation(final int position) {        mDragAdapter.removeItem(position);        final ViewTreeObserver observer = getViewTreeObserver();        observer.addOnPreDrawListener(new OnPreDrawListener() {            @Override            public boolean onPreDraw() {                observer.removeOnPreDrawListener(this);                animateReorder(position, getLastVisiblePosition() + 1);                return true;            }        });    }    private Handler mHandler = new Handler();    //用来处理是否为长按的Runnable    private Runnable mLongClickRunnable = new Runnable() {        @Override        public void run() {            isDrag = true; //设置可以拖拽            //mVibrator.vibrate(50); //震动一下(这里我不需要震动效果,所以我将其注释掉了,如果大家需要可以将其放开)            mStartDragItemView.setVisibility(View.INVISIBLE);//隐藏该item            //根据我们按下的点显示item镜像            createDragImage(mDragBitmap, mDownX, mDownY);        }    };    @Override    public void setAdapter(ListAdapter adapter) {        super.setAdapter(adapter);        if (adapter instanceof DragGridBaseAdapter) {            mDragAdapter = (DragGridBaseAdapter) adapter;        } else {            throw new IllegalStateException("the adapter must be implements DragGridAdapter");        }    }    /**     * 获取列数     */    @Override    public void setNumColumns(int numColumns) {        super.setNumColumns(numColumns);        mNumColumnsSet = true;        this.mNumColumns = numColumns;    }    /**     * 获取设置的列宽     */    @Override    public void setColumnWidth(int columnWidth) {        super.setColumnWidth(columnWidth);        mColumnWidth = columnWidth;    }    /**     * 获取水平方向的间隙     */    @Override    public void setHorizontalSpacing(int horizontalSpacing) {        super.setHorizontalSpacing(horizontalSpacing);        this.mHorizontalSpacing = horizontalSpacing;    }    /**     * 获取竖直方向的间隙     */    @Override    public void setVerticalSpacing(int verticalSpacing) {        super.setVerticalSpacing(verticalSpacing);        this.mVerticalSpacing = verticalSpacing;    }    /**     * 若列数设置为AUTO_FIT，我们在这里面计算具体的列数     */    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        if (mNumColumns == AUTO_FIT) {            int numFittedColumns;            if (mColumnWidth > 0) {                int gridWidth = Math.max(MeasureSpec.getSize(widthMeasureSpec) - getPaddingLeft()                        - getPaddingRight(), 0);                numFittedColumns = gridWidth / mColumnWidth;                if (numFittedColumns > 0) {                    while (numFittedColumns != 1) {                        if (numFittedColumns * mColumnWidth + (numFittedColumns - 1)                                * mHorizontalSpacing > gridWidth) {                            numFittedColumns--;                        } else {                            break;                        }                    }                } else {                    numFittedColumns = 1;                }            } else {                numFittedColumns = 2;            }            mNumColumns = numFittedColumns;        }        super.onMeasure(widthMeasureSpec, heightMeasureSpec);    }    /**     * 设置响应拖拽的毫秒数，默认是1000毫秒     *     * @param dragResponseMS     */    public void setDragResponseMS(long dragResponseMS) {        this.dragResponseMS = dragResponseMS;    }    @Override    public boolean dispatchTouchEvent(MotionEvent ev) {        switch (ev.getAction()) {            case MotionEvent.ACTION_DOWN:                mDownX = (int) ev.getX();                mDownY = (int) ev.getY();                //根据按下的X,Y坐标获取所点击item的position                mDragPosition = pointToPosition(mDownX, mDownY);                if (mDragPosition == AdapterView.INVALID_POSITION) {                    return super.dispatchTouchEvent(ev);                }                //使用Handler延迟dragResponseMS执行mLongClickRunnable                mHandler.postDelayed(mLongClickRunnable, dragResponseMS);                //根据position获取该item所对应的View                mStartDragItemView = getChildAt(mDragPosition - getFirstVisiblePosition());                //下面这几个距离大家可以参考我的博客上面的图来理解下                mPoint2ItemTop = mDownY - mStartDragItemView.getTop();                mPoint2ItemLeft = mDownX - mStartDragItemView.getLeft();                mOffset2Top = (int) (ev.getRawY() - mDownY);                mOffset2Left = (int) (ev.getRawX() - mDownX);                //获取DragGridView自动向上滚动的偏移量，小于这个值，DragGridView向下滚动                mDownScrollBorder = getHeight() / 5;                //获取DragGridView自动向下滚动的偏移量，大于这个值，DragGridView向上滚动                mUpScrollBorder = getHeight() * 4 / 5;                //开启mDragItemView绘图缓存                mStartDragItemView.setDrawingCacheEnabled(true);                //获取mDragItemView在缓存中的Bitmap对象                mDragBitmap = Bitmap.createBitmap(mStartDragItemView.getDrawingCache());                //这一步很关键，释放绘图缓存，避免出现重复的镜像                mStartDragItemView.destroyDrawingCache();                break;            case MotionEvent.ACTION_MOVE:                int moveX = (int) ev.getX();                int moveY = (int) ev.getY();                //如果我们在按下的item上面移动，只要不超过item的边界我们就不移除mRunnable                if (!isTouchInItem(mStartDragItemView, moveX, moveY)) {                    mHandler.removeCallbacks(mLongClickRunnable);                }                break;            case MotionEvent.ACTION_UP:                mHandler.removeCallbacks(mLongClickRunnable);                mHandler.removeCallbacks(mScrollRunnable);                break;        }        return super.dispatchTouchEvent(ev);    }    /**     * 是否点击在GridView的item上面     *     * @param x     * @param y     * @return     */    private boolean isTouchInItem(View dragView, int x, int y) {        if (dragView == null) {            return false;        }        int leftOffset = dragView.getLeft();        int topOffset = dragView.getTop();        if (x < leftOffset || x > leftOffset + dragView.getWidth()) {            return false;        }        if (y < topOffset || y > topOffset + dragView.getHeight()) {            return false;        }        return true;    }    @Override    public boolean onTouchEvent(MotionEvent ev) {        if (isDrag && mDragImageView != null) {            switch (ev.getAction()) {                case MotionEvent.ACTION_MOVE:                    moveX = (int) ev.getX();                    moveY = (int) ev.getY();                    //拖动item                    onDragItem(moveX, moveY);                    break;                case MotionEvent.ACTION_UP:                    onStopDrag();                    isDrag = false;                    break;            }            return true;        }        return super.onTouchEvent(ev);    }    /**     * 创建拖动的镜像     *     * @param bitmap     * @param downX  按下的点相对父控件的X坐标     * @param downY  按下的点相对父控件的X坐标     */    private void createDragImage(Bitmap bitmap, int downX, int downY) {        mWindowLayoutParams = new WindowManager.LayoutParams();        mWindowLayoutParams.format = PixelFormat.TRANSLUCENT; //图片之外的其他地方透明        mWindowLayoutParams.gravity = Gravity.TOP | Gravity.LEFT;        mWindowLayoutParams.x = downX - mPoint2ItemLeft + mOffset2Left;        mWindowLayoutParams.y = downY - mPoint2ItemTop + mOffset2Top - mStatusHeight;        mWindowLayoutParams.alpha = 0.55f; //透明度        mWindowLayoutParams.width = WindowManager.LayoutParams.WRAP_CONTENT;        mWindowLayoutParams.height = WindowManager.LayoutParams.WRAP_CONTENT;        mWindowLayoutParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE                | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE;        mDragImageView = new ImageView(getContext());        mDragImageView.setImageBitmap(bitmap);        mWindowManager.addView(mDragImageView, mWindowLayoutParams);    }    /**     * 从界面上面移动拖动镜像     */    private void removeDragImage() {        if (mDragImageView != null) {            mWindowManager.removeView(mDragImageView);            mDragImageView = null;        }    }    /**     * 拖动item，在里面实现了item镜像的位置更新，item的相互交换以及GridView的自行滚动     *     * @param     * @param     */    private void onDragItem(int moveX, int moveY) {        mWindowLayoutParams.x = moveX - mPoint2ItemLeft + mOffset2Left;        mWindowLayoutParams.y = moveY - mPoint2ItemTop + mOffset2Top - mStatusHeight;        mWindowManager.updateViewLayout(mDragImageView, mWindowLayoutParams); //更新镜像的位置        onSwapItem(moveX, moveY);        //GridView自动滚动        mHandler.post(mScrollRunnable);    }    /**     * 当moveY的值大于向上滚动的边界值，触发GridView自动向上滚动     * 当moveY的值小于向下滚动的边界值，触发GridView自动向下滚动     * 否则不进行滚动     */    private Runnable mScrollRunnable = new Runnable() {        @Override        public void run() {            int scrollY;            if (getFirstVisiblePosition() == 0 || getLastVisiblePosition() == getCount() - 1) {                mHandler.removeCallbacks(mScrollRunnable);            }            if (moveY > mUpScrollBorder) {                scrollY = speed;                mHandler.postDelayed(mScrollRunnable, 25);            } else if (moveY < mDownScrollBorder) {                scrollY = -speed;                mHandler.postDelayed(mScrollRunnable, 25);            } else {                scrollY = 0;                mHandler.removeCallbacks(mScrollRunnable);            }            smoothScrollBy(scrollY, 10);        }    };    /**     * 交换item,并且控制item之间的显示与隐藏效果     *     * @param moveX     * @param moveY     */    private void onSwapItem(int moveX, int moveY) {        //获取我们手指移动到的那个item的position        final int tempPosition = pointToPosition(moveX, moveY);        //假如tempPosition 改变了并且tempPosition不等于-1,则进行交换        if (tempPosition != mDragPosition && tempPosition != AdapterView.INVALID_POSITION && mAnimationEnd) {            /**             * 交换item             */            mDragAdapter.reorderItems(mDragPosition, tempPosition);            /**             * 设置新到的位置隐藏             */            mDragAdapter.setHideItem(tempPosition);            final ViewTreeObserver observer = getViewTreeObserver();            observer.addOnPreDrawListener(new OnPreDrawListener() {                @Override                public boolean onPreDraw() {                    observer.removeOnPreDrawListener(this);                    animateReorder(mDragPosition, tempPosition);                    mDragPosition = tempPosition;                    return true;                }            });        }    }    /**     * 创建移动动画     *     * @param view     * @param startX     * @param endX     * @param startY     * @param endY     * @return     */    private AnimatorSet createTranslationAnimations(View view, float startX,                                                    float endX, float startY, float endY) {        ObjectAnimator animX = ObjectAnimator.ofFloat(view, "translationX",                startX, endX);        ObjectAnimator animY = ObjectAnimator.ofFloat(view, "translationY",                startY, endY);        AnimatorSet animSetXY = new AnimatorSet();        animSetXY.playTogether(animX, animY);        return animSetXY;    }    /**     * item的交换动画效果     *     * @param oldPosition     * @param newPosition     */    private void animateReorder(final int oldPosition, final int newPosition) {        boolean isForward = newPosition > oldPosition;        List<Animator> resultList = new LinkedList<Animator>();        if (isForward) {            for (int pos = oldPosition; pos < newPosition; pos++) {                View view = getChildAt(pos - getFirstVisiblePosition());                if ((pos + 1) % mNumColumns == 0) {                    resultList.add(createTranslationAnimations(view,                            -(view.getWidth() + mHorizontalSpacing) * (mNumColumns - 1), 0,                            view.getHeight() + mVerticalSpacing, 0));                } else {                    resultList.add(createTranslationAnimations(view,                            view.getWidth() + mHorizontalSpacing, 0, 0, 0));                }            }        } else {            for (int pos = oldPosition; pos > newPosition; pos--) {                View view = getChildAt(pos - getFirstVisiblePosition());                if ((pos) % mNumColumns == 0) {                    resultList.add(createTranslationAnimations(view,                            (view.getWidth() + mHorizontalSpacing) * (mNumColumns - 1), 0,                            -view.getHeight() - mVerticalSpacing, 0));                } else {                    resultList.add(createTranslationAnimations(view,                            -view.getWidth() - mHorizontalSpacing, 0, 0, 0));                }            }        }        AnimatorSet resultSet = new AnimatorSet();        resultSet.playTogether(resultList);        resultSet.setDuration(300);        resultSet.setInterpolator(new AccelerateDecelerateInterpolator());        resultSet.addListener(new AnimatorListenerAdapter() {            @Override            public void onAnimationStart(Animator animation) {                mAnimationEnd = false;            }            @Override            public void onAnimationEnd(Animator animation) {                mAnimationEnd = true;            }        });        resultSet.start();    }    /**     * 停止拖拽我们将之前隐藏的item显示出来，并将镜像移除     */    private void onStopDrag() {        View view = getChildAt(mDragPosition - getFirstVisiblePosition());        if (view != null) {            view.setVisibility(View.VISIBLE);        }        mDragAdapter.setHideItem(-1);        removeDragImage();    }    /**     * 获取状态栏的高度     *     * @param context     * @return     */    private static int getStatusHeight(Context context) {        int statusHeight = 0;        Rect localRect = new Rect();        ((Activity) context).getWindow().getDecorView().getWindowVisibleDisplayFrame(localRect);        statusHeight = localRect.top;        if (0 == statusHeight) {            Class<?> localClass;            try {                localClass = Class.forName("com.android.internal.R$dimen");                Object localObject = localClass.newInstance();                int i5 = Integer.parseInt(localClass.getField("status_bar_height").get(localObject).toString());                statusHeight = context.getResources().getDimensionPixelSize(i5);            } catch (Exception e) {                e.printStackTrace();            }        }        return statusHeight;    }}