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@[Android|ListView|OnScrollListener]

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在写listview的时候很时候我们都会遇到一些场景

1. 判断当前是向上滚动，精确到px
2. 判断是否滚动到最后一个

但是Android提供给我们的OnScrollView不能给我们提供这些功能
于是我写了一个OnScrollListenerPro来完成这样的事情

package org.hangox.test;

import android.view.View;
import android.widget.AbsListView;

/**
 * Created With Android Studio
 * User 47
 * Date 2014-11-03
 * Time 17:42
 * 一个加强板的OnScrollListener
 * 可以提供向上滑动向下活动检测
 * 是否是最后一个检测
 */
public class OnScrollListenerPro implements AbsListView.OnScrollListener {
    private AbsListView mAbsListView;
    private int mLimit = 40;
    private int mLastScroll;
    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {
        mAbsListView = view;
    }

    /**
     * 设定最少滚动多少才算是滚动
     * @param mLimit
     */
    public void setLimit(int mLimit){
        this.mLimit = mLimit;
    }
    @Override
    public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
        mAbsListView = view;
        int currentScrollY = getScrollY();
        int dValue = currentScrollY - mLastScroll;
        if(dValue < -mLimit){//向上滚
            onScrollUp(mLastScroll,currentScrollY);
            mLastScroll = currentScrollY;
        }else if(dValue > mLimit ){//向下滚
            onScrollDown(mLastScroll,currentScrollY);
            mLastScroll = currentScrollY;
        }
        if(((totalItemCount > 0) && (firstVisibleItem + visibleItemCount >= totalItemCount - 1)))
            onLastItemShow();
    }

    /**
     * 向上滚动
     * @param lastScroll
     * @param currentScroll
     */
    public void onScrollUp(int lastScroll,int currentScroll){

    }


    /**
     * 向下滚动
     * @param lastScroll 上一次滚动值
     * @param currentScroll 这一次
     */
    public void onScrollDown(int lastScroll,int currentScroll){

    }

    public void onLastItemShow(){

    }



    public int getScrollY() {//获取滚动距离
        View c = mAbsListView.getChildAt(0);
        if (c == null) {
            return 0;
        }

        int firstVisiblePosition = mAbsListView.getFirstVisiblePosition();
        int top = c.getTop();

        int headerHeight = 0;
        if (firstVisiblePosition >= 1) {
            headerHeight = mAbsListView.getHeight();
        }
        return -top + firstVisiblePosition * c.getHeight() + headerHeight;
    }
}

使用很简单，重写其中的函数就可以了