<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent">

 <com.lcw.view.FixedHeaderScrollView.ObservableScrollView
 android:id="@+id/sv_contentView"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:scrollbars="none"
 >
 <LinearLayout
 android:id="@+id/ll_contentView"
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:orientation="vertical">
 <TextView
 android:id="@+id/tv_headerView"
 android:layout_width="match_parent"
 android:layout_height="200dp"
 android:text="我是头部布局"
 android:textSize="30sp"
 android:background="#ad29e1"
 android:gravity="center"/>
 <LinearLayout
 android:id="@+id/ll_topView"
 android:layout_width="match_parent"
 android:layout_height="50dp"
 android:gravity="center"
 android:orientation="vertical">
 <TextView
  android:id="@+id/tv_topView"
  android:layout_width="match_parent"
  android:layout_height="50dp"
  android:text="我是内层固定的布局"
  android:background="#3be42f"
  android:textSize="30sp"
  android:gravity="center"/>
 </LinearLayout>

 <TextView
 android:id="@+id/tv_contentView"
 android:layout_width="match_parent"
 android:layout_height="1000dp"
 android:text="我是内容布局"
 android:textSize="30sp"
 android:background="#dc7f28"
 android:paddingTop="160dp"
 android:gravity="top|center_horizontal"/>

 </LinearLayout>
 </com.lcw.view.FixedHeaderScrollView.ObservableScrollView>

 <LinearLayout
 android:id="@+id/ll_fixedView"
 android:layout_width="match_parent"
 android:layout_height="50dp"
 android:orientation="vertical"/>

</FrameLayout>

package com.lcw.view.FixedHeaderScrollView;

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

/**
 * 监听ScrollView的滑动数据
 * Create by: chenwei.li
 * Date: 2017/8/21
 * time: 11:36
 * Email: lichenwei.me@foxmail.com
 */
public class ObservableScrollView extends ScrollView{

 public ObservableScrollView(Context context) {
 this(context,null);
 }

 public ObservableScrollView(Context context, AttributeSet attrs) {
 this(context, attrs,0);
 }

 public ObservableScrollView(Context context, AttributeSet attrs, int defStyleAttr) {
 super(context, attrs, defStyleAttr);
 }


 private OnObservableScrollViewScrollChanged mOnObservableScrollViewScrollChanged;

 public void setOnObservableScrollViewScrollChanged(OnObservableScrollViewScrollChanged mOnObservableScrollViewScrollChanged) {
 this.mOnObservableScrollViewScrollChanged = mOnObservableScrollViewScrollChanged;
 }


 public interface OnObservableScrollViewScrollChanged{
 void onObservableScrollViewScrollChanged(int l, int t, int oldl, int oldt);
 }

 /**
 * @param l Current horizontal scroll origin. 当前滑动的x轴距离
 * @param t Current vertical scroll origin. 当前滑动的y轴距离
 * @param oldl Previous horizontal scroll origin. 上一次滑动的x轴距离
 * @param oldt Previous vertical scroll origin. 上一次滑动的y轴距离
 */
 @Override
 protected void onScrollChanged(int l, int t, int oldl, int oldt) {
 super.onScrollChanged(l, t, oldl, oldt);
 if(mOnObservableScrollViewScrollChanged!=null){
 mOnObservableScrollViewScrollChanged.onObservableScrollViewScrollChanged(l,t,oldl,oldt);
 }
 }
}

package com.lcw.view.FixedHeaderScrollView;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.LinearLayout;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity implements ObservableScrollView.OnObservableScrollViewScrollChanged{

 private ObservableScrollView sv_contentView;
 private LinearLayout ll_topView;
 private TextView tv_topView;
 private LinearLayout ll_fixedView;

 //用来记录内层固定布局到屏幕顶部的距离
 private int mHeight;


 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);

 sv_contentView= (ObservableScrollView) findViewById(R.id.sv_contentView);
 ll_topView= (LinearLayout) findViewById(R.id.ll_topView);
 tv_topView= (TextView) findViewById(R.id.tv_topView);
 ll_fixedView= (LinearLayout) findViewById(R.id.ll_fixedView);


 sv_contentView.setOnObservableScrollViewScrollChanged(this);

// ViewTreeObserver viewTreeObserver=ll_topView.getViewTreeObserver();
// viewTreeObserver.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
// @Override
// public void onGlobalLayout() {
// ll_topView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
// mHeight=ll_topView.getTop();
// }
// });

 }

 @Override
 public void onWindowFocusChanged(boolean hasFocus) {
 super.onWindowFocusChanged(hasFocus);
 if(hasFocus){
 //获取HeaderView的高度，当滑动大于等于这个高度的时候，需要把topView移除当前布局，放入到外层布局
 mHeight=ll_topView.getTop();
 }
 }

 /**
 * @param l Current horizontal scroll origin. 当前滑动的x轴距离
 * @param t Current vertical scroll origin. 当前滑动的y轴距离
 * @param oldl Previous horizontal scroll origin. 上一次滑动的x轴距离
 * @param oldt Previous vertical scroll origin. 上一次滑动的y轴距离
 */
 @Override
 public void onObservableScrollViewScrollChanged(int l, int t, int oldl, int oldt) {
 if(t>=mHeight){
 if(tv_topView.getParent()!=ll_fixedView){
  ll_topView.removeView(tv_topView);
  ll_fixedView.addView(tv_topView);
 }
 }else{
 if(tv_topView.getParent()!=ll_topView){
  ll_fixedView.removeView(tv_topView);
  ll_topView.addView(tv_topView);
 }
 }
 }
}