Android编程实现图标拖动效果的方法

package com.android.dragtest;
import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.FrameLayout;
public class DragView extends FrameLayout {
 private static final String TAG = "DragView";
 private float X;
 private float Y;
 private View mDragView;
 public DragView(Context context) {
  this(context, null);
 }
 public DragView(Context context, AttributeSet attrs) {
  this(context, attrs, 0);
 }
 public DragView(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
  mDragView = new View(context);
  mDragView.setLayoutParams(new LayoutParams(60, 60));
  mDragView.setBackgroundDrawable(getResources().getDrawable(R.drawable.gamecenter));
  mDragView.setVisibility(View.INVISIBLE);
  addView(mDragView);
 }
 public boolean onInterceptTouchEvent(MotionEvent ev) {
  final int action = ev.getAction();
  switch (action) {
  case MotionEvent.ACTION_DOWN:
   Log.d(TAG, "===============>onInterceptTouchEvent ACTION_DOWN");
   break;
  case MotionEvent.ACTION_MOVE:
   Log.d(TAG, "===============>onInterceptTouchEvent ACTION_MOVE");
   break;
  case MotionEvent.ACTION_UP:
   Log.d(TAG, "===============>onInterceptTouchEvent ACTION_UP");
   break;
  }
  return true;
 }
 public boolean onTouchEvent(MotionEvent ev) {
  final int action = ev.getAction();
  X = ev.getX();
  Y = ev.getY();
  switch (action) {
  case MotionEvent.ACTION_DOWN:
   Log.d(TAG, "onTouchEvent ACTION_DOWN");
   mDragView.layout((int)X - 30, (int)Y - 30, (int)X + 30, (int)Y + 30);
   mDragView.setVisibility(View.VISIBLE);
   break;
  case MotionEvent.ACTION_MOVE:
   Log.d(TAG, "onTouchEvent ACTION_MOVE x:" + X + " Y:" + Y);
   mDragView.layout((int)X - 30, (int)Y - 30, (int)X + 30, (int)Y + 30);
   break;
  case MotionEvent.ACTION_UP:
   Log.d(TAG, "onTouchEvent ACTION_UP");
   mDragView.setVisibility(View.INVISIBLE);
   break;
  }
  return true;
 }
}

package com.android.dragtest;
import android.app.Activity;
import android.os.Bundle;
public class DragTestActivity extends Activity {
 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
 }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 android:orientation="vertical" >
 <com.android.dragtest.DragView
  android:layout_width="match_parent"
  android:layout_height="match_parent">
 </com.android.dragtest.DragView>
</LinearLayout>