ScrollViewContainer制作上下两个页面带有拖拽效果的翻页

1、事件入口是dispatchTouchEvent(),它会先执行注册的onTouch监听,如果一切顺利的话，接着执行onTouchEvent，在onTouchEvent里会执行onClick监听。

2、无论是dispatchTouchEvent还是onTouchEvent，如果返回true表示这个事件已经被消费、处理了，不再往下传了。在dispathTouchEvent的源码里可以看到，如果onTouchEvent返回了true，那么它也返回true。如果dispatch***在执行onTouch监听的时候，onTouch返回了true，那么它也返回true，这个事件提前被onTouch消费掉了。就不再执行onTouchEvent了，更别说onClick监听了。

3、我们通常在onTouch监听了设置图片一旦被触摸就改变它的背景、透明度之类的，这个onTouch表示事件的时机。而在onClick监听了去具体干某些事。

下面通过代码来说明,自定义一个TestButton继承自Button，重写它的dispath***和onTouchEvent方法，为了简单只关注down和up事件。

参考：http://blog.csdn.net/yanzi1225627/article/details/22592831

具体原理不太清楚

大概就是通过 dispatchTouchEvent分析判断触摸事件，然后通过requestLayout触发onLayOut这个方法

重新摆放两个子控件这样子，具体的细节暂时不做研究啦

import android.content.Context;
import android.os.Build;
import android.os.Handler;
import android.os.Message;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.widget.RelativeLayout;
import android.widget.ScrollView;

import com.kidswant.ss.util.DisplayUtil;
import com.kidswant.ss.util.PreferencesUtil;

import java.lang.reflect.Method;
import java.util.Timer;
import java.util.TimerTask;

/**
 * 包含两个ScrollView的容器
 * 更多详解见博客http://dwtedx.com
 * 
 * @author chenjing
 * 
 */
public class ScrollViewContainer extends RelativeLayout {

	/**
	 * 自动上滑
	 */
	public static final int AUTO_UP = 0;
	/**
	 * 自动下滑
	 */
	public static final int AUTO_DOWN = 1;
	/**
	 * 动画完成
	 */
	public static final int DONE = 2;
	/**
	 * 动画速度
	 */
	public static final float SPEED = 6.5f;

	private boolean isMeasured = false;

	/**
	 * 用于计算手滑动的速度
	 */
	private VelocityTracker vt;

	private int mViewHeight;
	private int mViewWidth;

	private View topView;
	private View bottomView;

	private boolean canPullDown;
	private boolean canPullUp;
	private int state = DONE;

	/**
	 * 记录当前展示的是哪个view，0是topView，1是bottomView
	 */
	private int mCurrentViewIndex = 0;
	/**
	 * 手滑动距离，这个是控制布局的主要变量
	 */
	private float mMoveLen;
	private MyTimer mTimer;
	private float mLastY;
	/**
	 * 用于控制是否变动布局的另一个条件，mEvents==0时布局可以拖拽了，mEvents==-1时可以舍弃将要到来的第一个move事件，
	 * 这点是去除多点拖动剧变的关键
	 */
	private int mEvents;
	
//	public int getmCurrentViewIndex() {
//		return mCurrentViewIndex;
//	}

	private Handler handler = new Handler() {

		@Override
		public void handleMessage(Message msg) {
			if (mMoveLen != 0) {
				if (state == AUTO_UP) {
					mMoveLen -= SPEED;
					if (mMoveLen <= -mViewHeight) {
						mMoveLen = -mViewHeight;
						state = DONE;
						mCurrentViewIndex = 1;
						PreferencesUtil.setViewChange(System.currentTimeMillis());
					}
				} else if (state == AUTO_DOWN) {
					mMoveLen += SPEED;
					if (mMoveLen >= 0) {
						mMoveLen = 0;
						state = DONE;
						mCurrentViewIndex = 0;
					}
				} else {
					mTimer.cancel();
				}
			}
			requestLayout();
		}

	};

	public ScrollViewContainer(Context context) {
		super(context);
		init();
	}

	public ScrollViewContainer(Context context, AttributeSet attrs) {
		super(context, attrs);
		init();
	}

	public ScrollViewContainer(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		init();
	}

	private void init() {
		mTimer = new MyTimer(handler);
	}

	@Override
	public boolean dispatchTouchEvent(MotionEvent ev) {
		switch (ev.getActionMasked()) {
		case MotionEvent.ACTION_DOWN:
			if (vt == null)
				vt = VelocityTracker.obtain();
			else
				vt.clear();
			mLastY = ev.getY();
			vt.addMovement(ev);
			mEvents = 0;
			break;
		case MotionEvent.ACTION_POINTER_DOWN:
		case MotionEvent.ACTION_POINTER_UP:
			// 多一只手指按下或抬起时舍弃将要到来的第一个事件move，防止多点拖拽的bug
			mEvents = -1;
			break;
		case MotionEvent.ACTION_MOVE:
			vt.addMovement(ev);
			if (canPullUp && mCurrentViewIndex == 0 && mEvents == 0) {
				mMoveLen += (ev.getY() - mLastY);
				// 防止上下越界
				if (mMoveLen > 0) {
					mMoveLen = 0;
					mCurrentViewIndex = 0;
				} else if (mMoveLen < -mViewHeight) {
					mMoveLen = -mViewHeight;
					mCurrentViewIndex = 1;

				}
				if (mMoveLen < -8) {
					// 防止事件冲突
					ev.setAction(MotionEvent.ACTION_CANCEL);
				}
			} else if (canPullDown && mCurrentViewIndex == 1 && mEvents == 0) {
				mMoveLen += (ev.getY() - mLastY);
				// 防止上下越界
				if (mMoveLen < -mViewHeight) {
					mMoveLen = -mViewHeight;
					mCurrentViewIndex = 1;
				} else if (mMoveLen > 0) {
					mMoveLen = 0;
					mCurrentViewIndex = 0;
				}
				if (mMoveLen > 8 - mViewHeight) {
					// 防止事件冲突
					ev.setAction(MotionEvent.ACTION_CANCEL);
				}
			} else
				mEvents++;
			mLastY = ev.getY();
			requestLayout();
			break;
		case MotionEvent.ACTION_UP:
			mLastY = ev.getY();
			vt.addMovement(ev);
			vt.computeCurrentVelocity(700);
			// 获取Y方向的速度
			float mYV = vt.getYVelocity();
			if (mMoveLen == 0 || mMoveLen == -mViewHeight)
				break;
			if (Math.abs(mYV) < 500) {
				// 速度小于一定值的时候当作静止释放，这时候两个View往哪移动取决于滑动的距离
				if (mMoveLen <= -mViewHeight / 2) {
					state = AUTO_UP;
				} else if (mMoveLen > -mViewHeight / 2) {
					state = AUTO_DOWN;
				}
			} else {
				// 抬起手指时速度方向决定两个View往哪移动
				if (mYV < 0)
					state = AUTO_UP;
				else
					state = AUTO_DOWN;
			}
			mTimer.schedule(2);
			try {
				vt.recycle();
				vt = null;
			} catch (Exception e) {
				e.printStackTrace();
			}
			break;

		}
		super.dispatchTouchEvent(ev);
		return true;
	}

	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		topView.layout(0, (int) mMoveLen, mViewWidth,
				topView.getMeasuredHeight() + (int) mMoveLen);
		bottomView.layout(0, topView.getMeasuredHeight() + (int) mMoveLen,
				mViewWidth, topView.getMeasuredHeight() + (int) mMoveLen
						+ bottomView.getMeasuredHeight());
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
		if (!isMeasured) {
			isMeasured = true;
            int hei = getMeasuredHeight();

//			if (Build.VERSION.SDK_INT > 22) {
//				mViewHeight = hei - DisplayUtil.dip2px(getContext().getApplicationContext(), 46);
//			} else {
				String brand = android.os.Build.BRAND;
				if (TextUtils.equals("Meizu", brand) && hasSmartBar() || TextUtils.equals("samsung", brand)) {
					mViewHeight = hei - DisplayUtil.dip2px(getContext().getApplicationContext(),92);
				} else {
					mViewHeight = hei - DisplayUtil.dip2px(getContext().getApplicationContext(), 46);//考虑到标题栏的高度
				}
//			}

			mViewWidth = getMeasuredWidth();

			topView = getChildAt(0);
			bottomView = getChildAt(1);

			bottomView.setOnTouchListener(bottomViewTouchListener);
			topView.setOnTouchListener(topViewTouchListener);
		}
	}
	
	private boolean hasSmartBar() {
		try {
			// 新型号可用反射调用Build.hasSmartBar()
			Method method = Class.forName("android.os.Build").getMethod(
					"hasSmartBar");
			return ((Boolean) method.invoke(null)).booleanValue();
		} catch (Exception e) {

		}
		// 反射不到Build.hasSmartBar(),则用Build.DEVICE判断
		if (Build.DEVICE.equals("mx2")) {
			return true;
		} else if (Build.DEVICE.equals("mx") || Build.DEVICE.equals("m9")) {
			return false;
		}
		return false;
	}

	private OnTouchListener topViewTouchListener = new OnTouchListener() {

		@Override
		public boolean onTouch(View v, MotionEvent event) {
			ScrollView sv = (ScrollView) v;
			canPullUp = sv.getScrollY() == (sv.getChildAt(0).getMeasuredHeight() - sv
					.getMeasuredHeight()) && mCurrentViewIndex == 0;
			return false;
		}
	};
	private OnTouchListener bottomViewTouchListener = new OnTouchListener() {

		@Override
		public boolean onTouch(View v, MotionEvent event) {
			ScrollView sv = (ScrollView) v;
			canPullDown = sv.getScrollY() <= 0 && mCurrentViewIndex == 1;
			return false;
		}
	};

	class MyTimer {
		private Handler handler;
		private Timer timer;
		private MyTask mTask;

		public MyTimer(Handler handler) {
			this.handler = handler;
			timer = new Timer();
		}

		public void schedule(long period) {
			if (mTask != null) {
				mTask.cancel();
				mTask = null;
			}
			mTask = new MyTask(handler);
			timer.schedule(mTask, 0, period);
		}

		public void cancel() {
			if (mTask != null) {
				mTask.cancel();
				mTask = null;
			}
		}

		class MyTask extends TimerTask {
			private Handler handler;

			public MyTask(Handler handler) {
				this.handler = handler;
			}

			@Override
			public void run() {
				handler.obtainMessage().sendToTarget();
			}

		}
	}

}