Android监听ScrollView滑动距离的简单处理

本文实例为大家分享了Android监听ScrollView滑动距离的具体方法，供大家参考，具体内容如下

使用ScrollView时，有时候我们需要要获取它滑动的距离，Android的API给我们提供了设置监听的方法：

scrollView.setOnScrollChangeListener(new View.OnScrollChangeListener() {
            @Override
            public void onScrollChange(View v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
            }
        });

很遗憾的是：Call requires API 23
点进去看下View里面的OnScrollChangeListener在哪个方法里面监听位置：

/**
     * This is called in response to an internal scroll in this view (i.e., the
     * view scrolled its own contents). This is typically as a result of
     * {@link #scrollBy(int, int)} or {@link #scrollTo(int, int)} having been
     * called.
     *
     * @param l Current horizontal scroll origin.
     * @param t Current vertical scroll origin.
     * @param oldl Previous horizontal scroll origin.
     * @param oldt Previous vertical scroll origin.
     */
    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
        notifySubtreeAccessibilityStateChangedIfNeeded();
        if (AccessibilityManager.getInstance(mContext).isEnabled()) {
            postSendViewScrolledAccessibilityEventCallback();
        }
        mBackgroundSizeChanged = true;
        if (mForegroundInfo != null) {
            mForegroundInfo.mBoundsChanged = true;
        }
        final AttachInfo ai = mAttachInfo;
        if (ai != null) {
            ai.mViewScrollChanged = true;
        }
        if (mListenerInfo != null && mListenerInfo.mOnScrollChangeListener != null) {
            mListenerInfo.mOnScrollChangeListener.onScrollChange(this, l, t, oldl, oldt);
        }
    }

一看其实实现不难，不就是自定义个ScrollView, 里面多写个监听，实现如下：

import android.content.Context;
import android.util.AttributeSet;
import android.widget.ScrollView;
/**
 * Created by hucanhui on 16/7/28.
 */
public class ObservableScrollView extends ScrollView{
    private OnScollChangedListener onScollChangedListener = null;
    public ObservableScrollView(Context context) {
        super(context);
    }
    public ObservableScrollView(Context context, AttributeSet attrs,
                                int defStyle) {
        super(context, attrs, defStyle);
    }
    public ObservableScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }
    public void setOnScollChangedListener(OnScollChangedListener onScollChangedListener) {
        this.onScollChangedListener = onScollChangedListener;
    }
    @Override
    protected void onScrollChanged(int x, int y, int oldx, int oldy) {
        super.onScrollChanged(x, y, oldx, oldy);
        if (onScollChangedListener != null) {
            onScollChangedListener.onScrollChanged(this, x, y, oldx, oldy);
        }
    }
    public interface OnScollChangedListener {
        void onScrollChanged(ObservableScrollView scrollView, int x, int y, int oldx, int oldy);
    }
}

使用简单：

scrollView.setOnScollChangedListener(new ObservableScrollView.OnScollChangedListener() {
            @Override
            public void onScrollChanged(ObservableScrollView scrollView, int x, int y, int oldx, int oldy){
            }
        });