Android 左右滑屏 方向判断 ViewPager

如题，左右的时候需要预加载，所有要知道方向，但是原来的控件没有这个方法，所有，修改了下，代码如下做一个备份，欢迎指正！

原文：http://www.cnblogs.com/meiyitian/archive/2012/01/29/2330994.html

package com.meityitian.app.views;import android.content.Context;import android.support.v4.view.ViewPager;import android.util.AttributeSet;import android.util.Log;import com.meityitian.app.utils.Debug;/** * 重写，添加了判定滑动方向的方法 * @author zxy * */public class meityitianViewPager extends ViewPager {    private boolean left = false;    private boolean right = false;    private boolean isScrolling = false;    private int lastValue = -1;    private ChangeViewCallback changeViewCallback = null;    public meityitianViewPager(Context context, AttributeSet attrs) {        super(context, attrs);        init();    }    public meityitianViewPager(Context context) {        super(context);        init();    }    /**     * init method .*/    private void init() {        setOnPageChangeListener(listener);    }    /**     * listener ,to get move direction .*/    public  OnPageChangeListener listener = new OnPageChangeListener() {        @Override        public void onPageScrollStateChanged(int arg0) {            if (arg0 == 1) {                isScrolling = true;            } else {                isScrolling = false;            }            Debug.infoByTag("meityitianViewPager",                    "meityitianViewPager  onPageScrollStateChanged : arg0:"                            + arg0);            if (arg0 == 2) {                Debug.infoByTag("meityitianViewPager",                        "meityitianViewPager  onPageScrollStateChanged  direction left ? "                                + left);                Debug.infoByTag("meityitianViewPager",                        "meityitianViewPager  onPageScrollStateChanged  direction right ? "                                + right);                //notify ....                if(changeViewCallback!=null){                    changeViewCallback.changeView(left, right);                }                right = left = false;            }        }        @Override        public void onPageScrolled(int arg0, float arg1, int arg2) {            if (isScrolling) {                if (lastValue > arg2) {                    // 递减，向右侧滑动                    right = true;                    left = false;                } else if (lastValue < arg2) {                    // 递减，向右侧滑动                    right = false;                    left = true;                } else if (lastValue == arg2) {                    right = left = false;                }            }            Log.i("meityitianViewPager",                    "meityitianViewPager onPageScrolled  last :arg2  ,"                            + lastValue + ":" + arg2);            lastValue = arg2;        }        @Override        public void onPageSelected(int arg0) {            if(changeViewCallback!=null){                changeViewCallback.getCurrentPageIndex(arg0);            }        }    };        /**     * 得到是否向右侧滑动     * @return true 为右滑动*/    public boolean getMoveRight(){        return right;    }        /**     * 得到是否向左侧滑动     * @return true 为左做滑动*/    public boolean getMoveLeft(){        return left;    }        /**     *  滑动状态改变回调     * @author zxy     **/    public interface ChangeViewCallback{        /**         * 切换视图 ？决定于left和right 。         * @param left         * @param right*/        public  void changeView(boolean left,boolean right);        public  void  getCurrentPageIndex(int index);    }        /**     * set ...     * @param callback*/    public void  setChangeViewCallback(ChangeViewCallback callback){        changeViewCallback = callback;    }}