Android4.0以下View的Drag和Drop简单实现

主要代码部分：

实现View的onTouch方法,变换落点的X,Y坐标,定义两个变量存放拖动前的坐标位置.

int prevX,prevY;

    @Override
		    public boolean onTouch(final View v,final MotionEvent event)
		      {
		      final FrameLayout.LayoutParams par=(FrameLayout.LayoutParams)v.getLayoutParams();
		      switch(event.getAction())
		        {
		        case MotionEvent.ACTION_MOVE:
		          {
		          par.topMargin+=(int)event.getRawY()-prevY;
		          prevY=(int)event.getRawY();
		          par.leftMargin+=(int)event.getRawX()-prevX;
		          prevX=(int)event.getRawX();
		          v.setLayoutParams(par);
		          return true;
		          }
		        case MotionEvent.ACTION_UP:
		          {
		          par.topMargin+=(int)event.getRawY()-prevY;
		          par.leftMargin+=(int)event.getRawX()-prevX;
		          v.setLayoutParams(par);
		          return true;
		          }
		        case MotionEvent.ACTION_DOWN:
		          {
		          prevX=(int)event.getRawX();
		          prevY=(int)event.getRawY();
		          par.bottomMargin=-2*v.getHeight();
		          par.rightMargin=-2*v.getWidth();
		          v.setLayoutParams(par);
		          return true;
		          }
		        }
		      return false;
		      }
		  });

完整代码：

package com.light.dragdropview;
import android.app.Activity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.FrameLayout;
public class MainActivity extends Activity {
	public FrameLayout board;
	public View pawn;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);

		board = new FrameLayout(this);
		pawn = new View(this);

		setContentView(R.layout.activity_main);

		board = (FrameLayout) findViewById(R.id.Board);
		findViewById(R.id.Pawn).setOnTouchListener(new OnTouchListener()
		{
		    int prevX,prevY;
		    @Override
		    public boolean onTouch(final View v,final MotionEvent event)
		      {
		      final FrameLayout.LayoutParams par=(FrameLayout.LayoutParams)v.getLayoutParams();
		      switch(event.getAction())
		        {
		        case MotionEvent.ACTION_MOVE:
		          {
		          par.topMargin+=(int)event.getRawY()-prevY;
		          prevY=(int)event.getRawY();
		          par.leftMargin+=(int)event.getRawX()-prevX;
		          prevX=(int)event.getRawX();
		          v.setLayoutParams(par);
		          return true;
		          }
		        case MotionEvent.ACTION_UP:
		          {
		          par.topMargin+=(int)event.getRawY()-prevY;
		          par.leftMargin+=(int)event.getRawX()-prevX;
		          v.setLayoutParams(par);
		          return true;
		          }
		        case MotionEvent.ACTION_DOWN:
		          {
		          prevX=(int)event.getRawX();
		          prevY=(int)event.getRawY();
		          par.bottomMargin=-2*v.getHeight();
		          par.rightMargin=-2*v.getWidth();
		          v.setLayoutParams(par);
		          return true;
		          }
		        }
		      return false;
		      }
		  });

	}

}

布局XML：

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/Board"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_gravity="top" >

    <View
        android:id="@+id/Pawn"
        android:layout_width="40dp"
        android:layout_height="40dp"
        android:layout_gravity="top"
        android:background="@drawable/ic_launcher" >
    </View>

</FrameLayout>