Android编程中ViewPage判断左右滑动方向的方法

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;  } }