<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" >

    <ImageView

        android:id="@+id/iv_main"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:src="@drawable/test"/>

</RelativeLayout>

public class MainActivity extends Activity implements OnTouchListener {

	private ImageView iv_main;

	private RelativeLayout parentView;

	@Override

	protected void onCreate(Bundle savedInstanceState) {

		super.onCreate(savedInstanceState);

		setContentView(R.layout.activity_main);

		iv_main = (ImageView) findViewById(R.id.iv_main);

		parentView = (RelativeLayout) iv_main.getParent();

		/*

		int right = parentView.getRight(); //0

		int bottom = parentView.getBottom();   //0

		Toast.makeText(this, right+"---"+bottom, 1).show();

		*/

		//设置touch监听

		iv_main.setOnTouchListener(this);

	}

	private int lastX;

	private int lastY;

	private int maxRight;

	private int maxBottom;

	@Override

	public boolean onTouch(View v, MotionEvent event) {

		//得到事件的坐标

		int eventX = (int) event.getRawX();

		int eventY = (int) event.getRawY();

		switch (event.getAction()) {

		case MotionEvent.ACTION_DOWN:

			//得到父视图的right/bottom

			if(maxRight==0) {//保证只赋一次值

				maxRight = parentView.getRight();

				maxBottom = parentView.getBottom();

			}

			//第一次记录lastX/lastY

			lastX =eventX;

			lastY = eventY;

			break;

		case MotionEvent.ACTION_MOVE:

			//计算事件的偏移

			int dx = eventX-lastX;

			int dy = eventY-lastY;

			//根据事件的偏移来移动imageView

			int left = iv_main.getLeft()+dx;

			int top = iv_main.getTop()+dy;

			int right = iv_main.getRight()+dx;

			int bottom = iv_main.getBottom()+dy;

			//限制left  >=0

			if(left<0) {

				right += -left;

				left = 0;

			}

			//限制top

			if(top<0) {

				bottom += -top;

				top = 0;

			}

			//限制right <=maxRight

			if(right>maxRight) {

				left -= right-maxRight;

				right = maxRight;

			}

			//限制bottom <=maxBottom

			if(bottom>maxBottom) {

				top -= bottom-maxBottom;

				bottom = maxBottom;

			}

			iv_main.layout(left, top, right, bottom);

			//再次记录lastX/lastY

			lastX = eventX;

			lastY = eventY;

			break;

		default:

			break;

		}

		return true;//所有的motionEvent都交给imageView处理

	}

}