Android中解决WebView上下滑动监听问题

public class NewWebView extends WebView{

 private OnScrollChangeListener mOnScrollChangeListener;

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

 @Override 
 protected void onScrollChanged(int l, int t, int oldl, int oldt) {
  super.onScrollChanged(l, t, oldl, oldt);
  // webview的高度
  float webcontent = getContentHeight() * getScale();
  // 当前webview的高度
  float webnow = getHeight() + getScrollY();
  if (Math.abs(webcontent - webnow) < 1) {
   //处于底端 
   mOnScrollChangeListener.onPageEnd(l, t, oldl, oldt);
  } else if (getScrollY() == 0) {
   //处于顶端
   mOnScrollChangeListener.onPageTop(l, t, oldl, oldt);
  } else { 
   mOnScrollChangeListener.onScrollChanged(l, t, oldl, oldt); 
  } 
 }

 public void setOnScrollChangeListener(OnScrollChangeListener listener) {
  this.mOnScrollChangeListener = listener; 
 }

 public interface OnScrollChangeListener {

  public void onPageEnd(int l, int t, int oldl, int oldt);

  public void onPageTop(int l, int t, int oldl, int oldt);

  public void onScrollChanged(int l, int t, int oldl, int oldt); 

 }

}

public class NewsActivity extends AppCompatActivity {

 private NewsWebView mWebView;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_news);
  mWebView = (NewsWebView) findViewById(R.id.web_view);
  mWebView.setOnScrollChangeListener(new NewsWebView.OnScrollChangeListener() {
   @Override
   public void onPageEnd(int l, int t, int oldl, int oldt) {
    Logs.d("已经到达地端");
   }

   @Override
   public void onPageTop(int l, int t, int oldl, int oldt) {
    Logs.d("已经到达顶端");
   }

   @Override
   public void onScrollChanged(int l, int t, int oldl, int oldt) {
   }
  });