ScrollView监听滑动到底部、顶部

package com.supoin.androidtextshow;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.widget.ScrollView;

/**
* 作者： kaifang
* 时间： 2016/12/19 17:33
* 作用：
*/

public class ScrollViewExt extends ScrollView {

private boolean isScrolledToTop;
private boolean isScrolledToBottom;
private IScrollChangedListener mScrollChangedListener;

public ScrollViewExt(Context context) {
super(context);
}

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

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

public void setScrollViewListener(IScrollChangedListener scrollViewListener) {
this.mScrollChangedListener = scrollViewListener;
}

@Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
// We take the last son in the scrollview
View view = getChildAt(0);
if (view == null)
return;
int diff = (view.getBottom() - (getHeight() + getScrollY()));
//        System.out.println("diff= " + diff
//                + ",view.getBottom()=" + view.getBottom()
//                + ",this.getHeight()=" + getHeight()
//                + ",this.getScrollY()=" + getScrollY());
// if diff is zero, then the bottom has been reached
isScrolledToBottom = false;
isScrolledToTop = false;
if (diff == 0) {
isScrolledToBottom = true;
if (mScrollChangedListener != null)
mScrollChangedListener.onScrolledToBottom();
} else if (getScrollY() == 0) {
isScrolledToTop = true;
if (mScrollChangedListener != null)
mScrollChangedListener.onScrolledToTop();
}
}

public boolean isTopEnd() {
return isScrolledToTop;
}

public boolean isBottomEnd() {
return isScrolledToBottom;
}

/**
* 定义监听接口
*/
public interface IScrollChangedListener {
void onScrolledToBottom();

void onScrolledToTop();
}

}