<?xml version="1.0" encoding="utf-8"?> <GridView  xmlns:android="http://schemas.android.com/apk/res/android"  android:id="@+id/gridview"  android:layout_width="fill_parent"  android:layout_height="fill_parent"  android:columnWidth="90dp"  android:numColumns="auto_fit"  android:horizontalSpacing="10dp"  android:verticalSpacing="10dp"  android:stretchMode="columnWidth"  android:gravity="center"> </GridView> 

public class HelloGridView extends Activity {   /** Called when the activity is first created. */   @Override   protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.main);     GridView gridView=(GridView)findViewById(R.id.gridview);     gridView.setAdapter(new ImageAdapter(this));     //單擊GridView元素的響應     gridView.setOnItemClickListener(new OnItemClickListener() {        @Override       public void onItemClick(AdapterView<?> parent, View view,           int position, long id) {         //彈出單擊的GridView元素的位置         Toast.makeText(HelloGridView.this,mThumbIds[position], Toast.LENGTH_SHORT).show();       }     });   }   private class ImageAdapter extends BaseAdapter{     private Context mContext;      public ImageAdapter(Context context) {       this.mContext=context;     }      @Override     public int getCount() {       return mThumbIds.length;     }      @Override     public Object getItem(int position) {       return mThumbIds[position];     }      @Override     public long getItemId(int position) {       // TODO Auto-generated method stub       return 0;     }      @Override     public View getView(int position, View convertView, ViewGroup parent) {       //定義一個ImageView,顯示在GridView里       ImageView imageView;       if(convertView==null){         imageView=new ImageView(mContext);         imageView.setLayoutParams(new GridView.LayoutParams(85, 85));         imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);         imageView.setPadding(8, 8, 8, 8);       }else{         imageView = (ImageView) convertView;       }       imageView.setImageResource(mThumbIds[position]);       return imageView;     }              }   //展示圖片   private Integer[] mThumbIds = {       R.drawable.sample_2, R.drawable.sample_3,       R.drawable.sample_4, R.drawable.sample_5,       R.drawable.sample_6, R.drawable.sample_7,       R.drawable.sample_0, R.drawable.sample_1,       R.drawable.sample_2, R.drawable.sample_3,       R.drawable.sample_4, R.drawable.sample_5,       R.drawable.sample_6, R.drawable.sample_7,       R.drawable.sample_0, R.drawable.sample_1,       R.drawable.sample_2, R.drawable.sample_3,       R.drawable.sample_4, R.drawable.sample_5,       R.drawable.sample_6, R.drawable.sample_7   }; } 

package com.example.draggridview;  import android.app.Activity; import android.content.Context; import android.graphics.Bitmap; import android.graphics.PixelFormat; import android.graphics.Rect; import android.os.Handler; import android.os.Vibrator; import android.util.AttributeSet; import android.view.Gravity; import android.view.MotionEvent; import android.view.View; import android.view.WindowManager; import android.widget.AdapterView; import android.widget.GridView; import android.widget.ImageView;  public class DragGridView extends GridView{   /**    * DragGridView的item長按響應的時間， 默認是1000毫秒，也可以自行設置    */   private long dragResponseMS = 1000;      /**    * 是否可以拖拽，默認不可以    */   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;      /**    * 剛開始拖拽的item對應的View    */   private View mStartDragItemView = null;      /**    * 用于拖拽的鏡像，這里直接用一個ImageView    */   private ImageView mDragImageView;      /**    * 震動器    */   private Vibrator mVibrator;      private WindowManager mWindowManager;   /**    * item鏡像的布局參數    */   private WindowManager.LayoutParams mWindowLayoutParams;      /**    * 我們拖拽的item對應的Bitmap    */   private Bitmap mDragBitmap;      /**    * 按下的點到所在item的上邊緣的距離    */   private int mPoint2ItemTop ;       /**    * 按下的點到所在item的左邊緣的距離    */   private int mPoint2ItemLeft;      /**    * DragGridView距離屏幕頂部的偏移量    */   private int mOffset2Top;      /**    * DragGridView距離屏幕左邊的偏移量    */   private int mOffset2Left;      /**    * 狀態欄的高度    */   private int mStatusHeight;       /**    * DragGridView自動向下滾動的邊界值    */   private int mDownScrollBorder;      /**    * DragGridView自動向上滾動的邊界值    */   private int mUpScrollBorder;      /**    * DragGridView自動滾動的速度    */   private static final int speed = 20;      /**    * item發生變化回調的接口    */   private OnChanageListener onChanageListener;            public DragGridView(Context context) {     this(context, null);   }      public DragGridView(Context context, AttributeSet attrs) {     this(context, attrs, 0);   }    public DragGridView(Context context, AttributeSet attrs, int defStyle) {     super(context, attrs, defStyle);     mVibrator = (Vibrator) context.getSystemService(Context.VIBRATOR_SERVICE);     mWindowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);     mStatusHeight = getStatusHeight(context); //獲取狀態欄的高度        }      private Handler mHandler = new Handler();      //用來處理是否為長按的Runnable   private Runnable mLongClickRunnable = new Runnable() {          @Override     public void run() {       isDrag = true; //設置可以拖拽       mVibrator.vibrate(50); //震動一下       mStartDragItemView.setVisibility(View.INVISIBLE);//隱藏該item              //根據我們按下的點顯示item鏡像       createDragImage(mDragBitmap, mDownX, mDownY);     }   }; 

  /**    * 設置回調接口    * @param onChanageListener    */   public void setOnChangeListener(OnChanageListener onChanageListener){     this.onChanageListener = onChanageListener;   }      /**    * 設置響應拖拽的毫秒數，默認是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();              //根據按下的X,Y坐標獲取所點擊item的position       mDragPosition = pointToPosition(mDownX, mDownY);                     if(mDragPosition == AdapterView.INVALID_POSITION){         return super.dispatchTouchEvent(ev);       }              //使用Handler延遲dragResponseMS執行mLongClickRunnable       mHandler.postDelayed(mLongClickRunnable, dragResponseMS);              //根據position獲取該item所對應的View       mStartDragItemView = getChildAt(mDragPosition - getFirstVisiblePosition());              //下面這幾個距離大家可以參考我的博客上面的圖來理解下       mPoint2ItemTop = mDownY - mStartDragItemView.getTop();       mPoint2ItemLeft = mDownX - mStartDragItemView.getLeft();              mOffset2Top = (int) (ev.getRawY() - mDownY);       mOffset2Left = (int) (ev.getRawX() - mDownX);              //獲取DragGridView自動向上滾動的偏移量，小于這個值，DragGridView向下滾動       mDownScrollBorder = getHeight() /4;       //獲取DragGridView自動向下滾動的偏移量，大于這個值，DragGridView向上滾動       mUpScrollBorder = getHeight() * 3/4;                            //開啟mDragItemView繪圖緩存       mStartDragItemView.setDrawingCacheEnabled(true);       //獲取mDragItemView在緩存中的Bitmap對象       mDragBitmap = Bitmap.createBitmap(mStartDragItemView.getDrawingCache());       //這一步很關鍵，釋放繪圖緩存，避免出現重復的鏡像       mStartDragItemView.destroyDrawingCache();                     break;     case MotionEvent.ACTION_MOVE:       int moveX = (int)ev.getX();       int moveY = (int) ev.getY();              //如果我們在按下的item上面移動，只要不超過item的邊界我們就不移除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);   } 

  /**    * 是否點擊在GridView的item上面    * @param itemView    * @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();         //拖動item         onDragItem(moveX, moveY);         break;       case MotionEvent.ACTION_UP:         onStopDrag();         isDrag = false;         break;       }       return true;     }     return super.onTouchEvent(ev);   } 

  /**    * 創建拖動的鏡像    * @param bitmap    * @param downX    *     按下的點相對父控件的X坐標    * @param downY    *     按下的點相對父控件的X坐標    */   private void createDragImage(Bitmap bitmap, int downX , int downY){     mWindowLayoutParams = new WindowManager.LayoutParams();     mWindowLayoutParams.format = PixelFormat.TRANSLUCENT; //圖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);    }    

  /**    * 從界面上面移動拖動鏡像    */   private void removeDragImage(){     if(mDragImageView != null){       mWindowManager.removeView(mDragImageView);       mDragImageView = null;     }   } 

  /**    * 拖動item，在里面實現了item鏡像的位置更新，item的相互交換以及GridView的自行滾動    * @param x    * @param y    */   private void onDragItem(int moveX, int moveY){     mWindowLayoutParams.x = moveX - mPoint2ItemLeft + mOffset2Left;     mWindowLayoutParams.y = moveY - mPoint2ItemTop + mOffset2Top - mStatusHeight;     mWindowManager.updateViewLayout(mDragImageView, mWindowLayoutParams); //更新鏡像的位置     onSwapItem(moveX, moveY);          //GridView自動滾動     mHandler.post(mScrollRunnable);   } 

  /**    * 當moveY的值大于向上滾動的邊界值，觸發GridView自動向上滾動    * 當moveY的值小于向下滾動的邊界值，觸犯GridView自動向下滾動    * 否則不進行滾動    */   private Runnable mScrollRunnable = new Runnable() {          @Override     public void run() {       int scrollY;       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);       }              //當我們的手指到達GridView向上或者向下滾動的偏移量的時候，可能我們手指沒有移動，但是DragGridView在自動的滾動       //所以我們在這里調用下onSwapItem()方法來交換item       onSwapItem(moveX, moveY);                     smoothScrollBy(scrollY, 10);     }   }; 

  /**    * 交換item,并且控制item之間的顯示與隱藏效果    * @param moveX    * @param moveY    */   private void onSwapItem(int moveX, int moveY){     //獲取我們手指移動到的那個item的position     int tempPosition = pointToPosition(moveX, moveY);          //假如tempPosition 改變了并且tempPosition不等于-1,則進行交換     if(tempPosition != mDragPosition && tempPosition != AdapterView.INVALID_POSITION){       if(onChanageListener != null){         onChanageListener.onChange(mDragPosition, tempPosition);       }              getChildAt(tempPosition - getFirstVisiblePosition()).setVisibility(View.INVISIBLE);//拖動到了新的item,新的item隱藏掉       getChildAt(mDragPosition - getFirstVisiblePosition()).setVisibility(View.VISIBLE);//之前的item顯示出來              mDragPosition = tempPosition;     }   } 

     /**    * 停止拖拽我們將之前隱藏的item顯示出來，并將鏡像移除    */   private void onStopDrag(){     View view = getChildAt(mDragPosition - getFirstVisiblePosition());     if(view != null){       view.setVisibility(View.VISIBLE);     }     ((DragAdapter)this.getAdapter()).setItemHide(-1);     removeDragImage();   } 

  /**    * 獲取狀態欄的高度    * @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;   } 

  /**    *    * @author xiaanming    *    */   public interface OnChanageListener{          /**      * 當item交換位置的時候回調的方法，我們只需要在該方法中實現數據的交換即可      * @param form      *     開始的position      * @param to      *     拖拽到的position      */     public void onChange(int form, int to);   } } 

首先看DragGridView的事件分發方法，不了解Android事件分發的可以先去了解下，Android事件分發對于自定義控件很重要，簡單說下，當我們點擊DragGridView的Item,先會去執行dispatchTouchEvent()方法將事件分發下去，所以我們要重寫dispatchTouchEvent()方法在手指按下的時候根據pointToPosition()方法來獲取我們按下的item的position,根據getChildAt()方法來獲取該position上面所對應的View, 并且開啟長按的定時器，默認時間為1000毫秒，如果在1000毫秒內手指抬起或者手指在屏幕上滑動出了該item，則取消長按定時器，否則就表示可以進行拖拽，手機友好的震動一下，隱藏我們長按的Item，屏幕調用createDragImage()方法來創建我們長按的item的鏡像，創建Item的鏡像使用的是WindowManager類，該類可以創建一個窗體顯示在Activity之上，
再此之前大家先要理解這幾個距離，理解這幾個距離之前要首先知道getRawX(),getRawY()和getX(),getY()的區別，getRawX(),getRawY()是相對于屏幕的原點的距離，而getX(),getY()是相對于控件左上方的點的距離，為了方便大家理解我用Word簡單的畫了下圖，畫得不好，大家將就的看下，紅色框框為我們的GridView

• mPoint2ItemTop 手指按下的點到該Item的上邊緣的距離，如上圖的1號線
• mPoint2ItemLeft 手指按下的點到該Item的左邊緣的距離，如上圖的2號線
• mOffset2Top  DragGridView的上邊緣到屏幕上邊緣的距離，如上圖的3號線，這個距離包裹狀態欄，標題欄，或者一些在DragGridView上面的布局的高度，這個很重要我們現實Item鏡像需要用到
• mOffset2Left DragGridView的左邊緣到屏幕左邊緣的距離，如上圖的4號線，我這個Demo的這個距離為0，因為我設置DragGridView的寬度為充滿屏幕，但是我們要考慮假如DragGridView與屏幕左邊緣設置了間隙或者左邊有其他的布局的情形
• mDownScrollBorder 這個距離表示當DragGridView的item過多的時候，手機一屏顯示不完全，我們拖動Item鏡像到這個高度的時候，DragGridView自動向下滾動，如上圖的5號線
• .mUpScrollBorder 這個和mDownScrollBorder相反，當我們大于這個高度的時候，DragGridView自動向上滾動，如上圖的6號線

理解了這六個距離，我們就來看看創建Item鏡像的方法里面，其他的我不多說，首先設置format為PixelFormat.TRANSLUCENT，表示除了我們顯示圖片和文字的其他地方為透明，之后就是x，y這兩個距離的計算，計算的是item的左上角的坐標，理解了上面這六個距離我們很容易得出x,y的坐標，可是你會發現y的坐標減去了狀態欄的高度，這點大家需要注意下，另外我們需要獲取item的繪制緩存的Bitmap對象，然后將Bitmap設置到一個ImageView上面，為什么要這么做呢？如果調用addView()方法將item 直接添加到WindowManager里面，會有異常產生，因為item已經有了自己歸屬的父容器DragGridView，所有我們這里使用一個ImageView來代替item添加到WindowManager里面

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"   xmlns:tools="http://schemas.android.com/tools"   android:layout_width="match_parent"   android:layout_height="match_parent" >    <com.example.draggridview.DragGridView     android:id="@+id/dragGridView"     android:listSelector="@android:color/transparent"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:cacheColorHint="@android:color/transparent"     android:verticalSpacing="10dip"     android:horizontalSpacing="10dip"     android:stretchMode="columnWidth"      android:gravity="center"      android:numColumns="3" >   </com.example.draggridview.DragGridView>  </RelativeLayout> 

<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"   android:layout_width="fill_parent"   android:layout_height="wrap_content"   android:background="@android:color/transparent" >    <ImageView     android:id="@+id/item_image"     android:scaleType="centerCrop"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:layout_centerHorizontal="true" >   </ImageView>    <TextView     android:id="@+id/item_text"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:layout_below="@+id/item_image"     android:layout_centerHorizontal="true" >   </TextView>  </RelativeLayout> 

package com.example.draggridview;  import java.util.ArrayList; import java.util.Collections; import java.util.HashMap; import java.util.List;  import android.app.Activity; import android.os.Bundle; import android.widget.SimpleAdapter;  import com.example.draggridview.DragGridView.OnChanageListener; public class MainActivity extends Activity {   private List<HashMap<String, Object>> dataSourceList = new ArrayList<HashMap<String, Object>>();    @Override   protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);      DragGridView mDragGridView = (DragGridView) findViewById(R.id.dragGridView);     for (int i = 0; i < 30; i++) {       HashMap<String, Object> itemHashMap = new HashMap<String, Object>();       itemHashMap.put("item_image",R.drawable.com_tencent_open_notice_msg_icon_big);       itemHashMap.put("item_text", "拖拽 " + Integer.toString(i));       dataSourceList.add(itemHashMap);     }           final SimpleAdapter mSimpleAdapter = new SimpleAdapter(this, dataSourceList,         R.layout.grid_item, new String[] { "item_image", "item_text" },         new int[] { R.id.item_image, R.id.item_text });          mDragGridView.setAdapter(mSimpleAdapter);          mDragGridView.setOnChangeListener(new OnChanageListener() {              @Override       public void onChange(int from, int to) {         HashMap<String, Object> temp = dataSourceList.get(from);         //直接交互item //       dataSourceList.set(from, dataSourceList.get(to)); //       dataSourceList.set(to, temp); //       dataSourceList.set(to, temp);                           //這里的處理需要注意下         if(from < to){           for(int i=from; i<to; i++){             Collections.swap(dataSourceList, i, i+1);           }         }else if(from > to){           for(int i=from; i>to; i--){             Collections.swap(dataSourceList, i, i-1);           }         }                  dataSourceList.set(to, temp);                  mSimpleAdapter.notifyDataSetChanged();                         }     });        }  } 

HashMap<String, Object> temp = dataSourceList.get(from);         //直接交互item //       dataSourceList.set(from, dataSourceList.get(to)); //       dataSourceList.set(to, temp);