原文地址：

运行效果: 

 

main.xml

MainActivity.java

package com.cn;import android.app.Activity;import android.os.Bundle;/** *  * 
 * Title: MainActivity.java * 
 * 
 * E-Mail: 176291935@qq.com * 
 * 
 * QQ: 176291935 * 
 * 
 * Http: iaiai.iteye.com * 
 * 
 * Create time: 2011-10-13 * 
 *  * @author 丸子 * @version 0.0.1 */public class MainActivity extends Activity {	/** Called when the activity is first created. */	@Override	public void onCreate(Bundle savedInstanceState) {		super.onCreate(savedInstanceState);		setContentView(R.layout.main);	}}

ScrollLayout.java

package com.cn;import android.content.Context;import android.util.AttributeSet;import android.util.Log;import android.view.MotionEvent;import android.view.VelocityTracker;import android.view.View;import android.view.ViewConfiguration;import android.view.ViewGroup;import android.widget.Scroller;/** *  * 
 * Title: ScrollLayout.java * 
 * 
 * E-Mail: 176291935@qq.com * 
 * 
 * QQ: 176291935 * 
 * 
 * Http: iaiai.iteye.com * 
 * 
 * Create time: 2011-10-13 * 
 *  * @author 丸子 * @version 0.0.1 */public class ScrollLayout extends ViewGroup {	private static final String TAG = "ScrollLayout";	private Scroller mScroller;	private VelocityTracker mVelocityTracker;	private int mCurScreen;	private int mDefaultScreen = 0;	private static final int TOUCH_STATE_REST = 0;	private static final int TOUCH_STATE_SCROLLING = 1;	private static final int SNAP_VELOCITY = 600;	private int mTouchState = TOUCH_STATE_REST;	private int mTouchSlop;	private float mLastMotionX;	private float mLastMotionY;	public ScrollLayout(Context context, AttributeSet attrs) {		this(context, attrs, 0);	}	public ScrollLayout(Context context, AttributeSet attrs, int defStyle) {		super(context, attrs, defStyle);		mScroller = new Scroller(context);		mCurScreen = mDefaultScreen;		mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();	}	@Override	protected void onLayout(boolean changed, int l, int t, int r, int b) {		if (changed) {			int childLeft = 0;			final int childCount = getChildCount();			for (int i = 0; i < childCount; i++) {				final View childView = getChildAt(i);				if (childView.getVisibility() != View.GONE) {					final int childWidth = childView.getMeasuredWidth();					childView.layout(childLeft, 0, childLeft + childWidth,							childView.getMeasuredHeight());					childLeft += childWidth;				}			}		}	}	@Override	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {		Log.e(TAG, "onMeasure");		super.onMeasure(widthMeasureSpec, heightMeasureSpec);		final int width = MeasureSpec.getSize(widthMeasureSpec);		final int widthMode = MeasureSpec.getMode(widthMeasureSpec);		if (widthMode != MeasureSpec.EXACTLY) {			throw new IllegalStateException(					"ScrollLayout only canmCurScreen run at EXACTLY mode!");		}		final int heightMode = MeasureSpec.getMode(heightMeasureSpec);		if (heightMode != MeasureSpec.EXACTLY) {			throw new IllegalStateException(					"ScrollLayout only can run at EXACTLY mode!");		}		// The children are given the same width and height as the scrollLayout		final int count = getChildCount();		for (int i = 0; i < count; i++) {			getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);		}		// Log.e(TAG, "moving to screen "+mCurScreen);		scrollTo(mCurScreen * width, 0);	}	/**	 * 	 * According to the position of current layout	 * 	 * scroll to the destination page.	 */	public void snapToDestination() {		final int screenWidth = getWidth();		final int destScreen = (getScrollX() + screenWidth / 2) / screenWidth;		snapToScreen(destScreen);	}	public void snapToScreen(int whichScreen) {		// get the valid layout page		whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));		if (getScrollX() != (whichScreen * getWidth())) {			final int delta = whichScreen * getWidth() - getScrollX();			mScroller.startScroll(getScrollX(), 0, delta, 0,					Math.abs(delta) * 2);			mCurScreen = whichScreen;			invalidate(); // Redraw the layout		}	}	public void setToScreen(int whichScreen) {		whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));		mCurScreen = whichScreen;		scrollTo(whichScreen * getWidth(), 0);	}	public int getCurScreen() {		return mCurScreen;	}	@Override	public void computeScroll() {		if (mScroller.computeScrollOffset()) {			scrollTo(mScroller.getCurrX(), mScroller.getCurrY());			postInvalidate();		}	}	@Override	public boolean onTouchEvent(MotionEvent event) {		if (mVelocityTracker == null) {			mVelocityTracker = VelocityTracker.obtain();		}		mVelocityTracker.addMovement(event);		final int action = event.getAction();		final float x = event.getX();		final float y = event.getY();		switch (action) {		case MotionEvent.ACTION_DOWN:			Log.e(TAG, "event down!");			if (!mScroller.isFinished()) {				mScroller.abortAnimation();			}			mLastMotionX = x;			break;		case MotionEvent.ACTION_MOVE:			int deltaX = (int) (mLastMotionX - x);			mLastMotionX = x;			scrollBy(deltaX, 0);			break;		case MotionEvent.ACTION_UP:			Log.e(TAG, "event : up");			// if (mTouchState == TOUCH_STATE_SCROLLING) {			final VelocityTracker velocityTracker = mVelocityTracker;			velocityTracker.computeCurrentVelocity(1000);			int velocityX = (int) velocityTracker.getXVelocity();			Log.e(TAG, "velocityX:" + velocityX);			if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {				// Fling enough to move left				Log.e(TAG, "snap left");				snapToScreen(mCurScreen - 1);			} else if (velocityX < -SNAP_VELOCITY					&& mCurScreen < getChildCount() - 1) {				// Fling enough to move right				Log.e(TAG, "snap right");				snapToScreen(mCurScreen + 1);			} else {				snapToDestination();			}			// if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {			//			// // Fling enough to move left			//			// Log.e(TAG, "snap left");			// if (mCurScreen > getChildCount() - 1) {			// View v1 = getChildAt(0);			// View v2 = getChildAt(1);			// View v3 = getChildAt(2);			//			// }			// snapToScreen(mCurScreen - 1);			//			// } else if (velocityX < -SNAP_VELOCITY			//			// && mCurScreen < getChildCount() - 1) {			//			// // Fling enough to move right			//			// Log.e(TAG, "snap right");			//			// snapToScreen(mCurScreen + 1);			//			// } else {			//			// snapToDestination();			//			// }			//			// if (mVelocityTracker != null) {			//			// mVelocityTracker.recycle();			//			// mVelocityTracker = null;			//			// }			// }			mTouchState = TOUCH_STATE_REST;			break;		case MotionEvent.ACTION_CANCEL:			mTouchState = TOUCH_STATE_REST;			break;		}		return true;	}	@Override	public boolean onInterceptTouchEvent(MotionEvent ev) {		Log.e(TAG, "onInterceptTouchEvent-slop:" + mTouchSlop + "; action = "				+ ev.getAction());		final int action = ev.getAction();		if ((action == MotionEvent.ACTION_MOVE)				&& (mTouchState != TOUCH_STATE_REST)) {			Log.e(TAG, "onInterceptTouchEvent-action:" + action);			return true;		}		final float x = ev.getX();		final float y = ev.getY();		switch (action) {		case MotionEvent.ACTION_MOVE:			final int xDiff = (int) Math.abs(mLastMotionX - x);			Log.e(TAG, "onInterceptTouchEvent-move: xDiff = " + xDiff					+ "; mLastMotionX = " + mLastMotionX);			if (xDiff > mTouchSlop) {				mTouchState = TOUCH_STATE_SCROLLING;			}			break;		case MotionEvent.ACTION_DOWN:			mLastMotionX = x;			mLastMotionY = y;			Log.e(TAG, "onInterceptTouchEvent-down: x = " + x + "; y = " + y);			mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST					: TOUCH_STATE_SCROLLING;			break;		case MotionEvent.ACTION_CANCEL:		case MotionEvent.ACTION_UP:			Log.e(TAG, "onInterceptTouchEvent-up: mLastMotionX = "					+ mLastMotionX);			mTouchState = TOUCH_STATE_REST;			break;		}		return mTouchState != TOUCH_STATE_REST;	}}