RecyclerView 滑动隐藏，显示ToolBar

落日映苍穹つ 2022-07-12 05:39 167阅读 0赞

### 一：去除自带的ActionBar，在styles.xml ###

### 二：布局文件，注意这里使用FrameLayout，是为了把ToolBar叠加放在RecyclerView上，**如果不这样，当你隐藏ToolBar时，原ToolBar所在位置会出现空白。** ###

<?xml version="1.0" encoding="utf-8"?>
    <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent">
        <android.support.v7.widget.RecyclerView android:id="@+id/rv" android:layout_width="match_parent" android:layout_height="wrap_content"/>
    
        <android.support.v7.widget.Toolbar android:id="@+id/toolbar" android:layout_width="match_parent" android:layout_height="?actionBarSize" android:background="?attr/colorPrimary"/>
    
    </FrameLayout>

### 三：具体实现 ###

package com.example.kirito.testapp.testtoolbarscroll;
    
    import android.animation.Animator;
    import android.animation.AnimatorListenerAdapter;
    import android.os.Bundle;
    import android.support.annotation.Nullable;
    import android.support.v7.app.AppCompatActivity;
    import android.support.v7.widget.LinearLayoutManager;
    import android.support.v7.widget.RecyclerView;
    import android.support.v7.widget.Toolbar;
    import android.util.Log;
    import android.view.View;
    import android.view.animation.AccelerateInterpolator;
    import android.view.animation.LinearInterpolator;
    
    import com.example.kirito.testapp.R;
    
    import java.util.ArrayList;
    import java.util.List;
    
    /** * Created by kirito on 2017.02.13. */
    
    public class TooBarScroll extends AppCompatActivity { 
        private Toolbar toolbar;
        private RecyclerView rv;
        private RvAdapter adapter;
        private List<String> list;
    
        private static int THRESHOLD_OFFSET = 10;
    
        private static final String TAG = "TooBarScroll";
    
        @Override
        protected void onCreate(@Nullable Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.toobar_scroll);
    
            toolbar = (Toolbar) findViewById(R.id.toolbar);
            setSupportActionBar(toolbar);
            getSupportActionBar().setTitle(R.string.app_name);
            rv = (RecyclerView) findViewById(R.id.rv);
    
            rv.setLayoutManager(new LinearLayoutManager(this));
            list = new ArrayList<>();
            for (int i = 0; i < 100; i++) {
                list.add(i + "");
            }
            adapter = new RvAdapter(this);
            rv.setAdapter(adapter);
            adapter.addAll(list);
    
            rv.addOnScrollListener(new RecyclerView.OnScrollListener() {
                boolean controlVisible = true;
                int scrollDistance = 0;
    
                //onScrolled 滑动停止的时候调用
                @Override
                public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                    super.onScrolled(recyclerView, dx, dy);
    
                    if (controlVisible && scrollDistance > THRESHOLD_OFFSET){
       //手指上滑即Scroll向下滚动的时候，dy为正
                        animationHide();
    
                        //重置使下面的if语句起作用
                        controlVisible = false;
                        scrollDistance = 0;
                    }else if (!controlVisible && scrollDistance < -THRESHOLD_OFFSET){
       //手指下滑即Scroll向上滚动的时候，dy为负
                        animationShow();
                        controlVisible = true;
                        scrollDistance = 0;
                    }
    
                    //当scrollDistance累计到隐藏（显示)ToolBar之后，如果Scroll向下（向上）滚动，则停止对scrollDistance的累加
                    //直到Scroll开始往反方向滚动，再次启动scrollDistance的累加
                    if ((controlVisible && dy > 0) || (!controlVisible && dy < 0)){
                        scrollDistance += dy;
                    }
                }
            });
        }
    
        private void animationShow() {
            toolbar.animate()
                    .setInterpolator(new AccelerateInterpolator(1))
                    .setDuration(180)
                    .translationY(0);
        }
    
        private void animationHide(){
    
            toolbar.animate()
                    .translationY(-toolbar.getBottom())
                    .setInterpolator(new LinearInterpolator())
                    .setDuration(180)；
    
        }
    }

效果图：  
![这里写图片描述][SouthEast]

--------------------

**这里有个问题**，ToolBar把RecyclerView最开头的几行挡住了，因为布局文件里使用的是FrameLayout。

### 四：此时有两个解决方法，一是对RecyclerView的属性进行修改 ###

<android.support.v7.widget.RecyclerView
            android:id="@+id/rv"
            android:paddingTop="?actionBarSize"
            android:clipToPadding="false"//若没有这句在隐藏ToolBar的时候会出现空白，如下所示
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>

![这里写图片描述][SouthEast 1]

改进后的效果

![这里写图片描述][SouthEast 2]

--------------------

### 五：第二种解决方法：在原ToolBar下面给RecyclerView添加一个子View ###

1.修改的RecyclerView adapter

package com.example.kirito.testapp.testtoolbarscroll;
    
    import android.content.Context;
    import android.support.v7.widget.RecyclerView;
    import android.view.LayoutInflater;
    import android.view.ViewGroup;
    
    import com.example.kirito.testapp.R;
    
    import java.util.ArrayList;
    import java.util.List;
    
    /** * Created by kirito on 2017.02.13. */
    
    public class RvAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
        private LayoutInflater mLayoutInflater;
        private List<String> list = new ArrayList<>();
    
        private int hearder = 0;
        private int item = 1;
    
        public RvAdapter(Context mContext) {
            mLayoutInflater = LayoutInflater.from(mContext);
        }
    
        public void addAll(List<String> items){
            list = items;
        }
    
        @Override
        public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            //添加header
            if (viewType == 0){
                return new Holder(mLayoutInflater.inflate(R.layout.rv_header,parent,false));
            }else {
                return new Holder(mLayoutInflater.inflate(R.layout.rv_item,parent,false),0);
            }
        }
    
        @Override
        public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
            //不是header才绑定数据
            if (position != 0){
                ((Holder)holder).bindHolder(list.get(position - 1));
            }
        }
    
        @Override
        public int getItemViewType(int position) {
            if (position == 0){
                return hearder;
            }else {
                return item;
            }
        }
    
        @Override
        public int getItemCount() {
            //count + 1
            return list.size() + 1;
        }
    }

2.修改的RecyclerView.ViewHolder

package com.example.kirito.testapp.testtoolbarscroll;
    
    import android.support.v7.widget.RecyclerView;
    import android.view.View;
    import android.widget.TextView;
    
    import com.example.kirito.testapp.R;
    
    /** * Created by kirito on 2017.02.13. */
    
    public class Holder extends RecyclerView.ViewHolder { 
        private TextView tv;
    
        //使用不同的构造器区分
        public Holder(View itemView) {
            super(itemView);
        }
    
        public Holder(View itemView, int flag) {
            super(itemView);
            tv = (TextView) itemView.findViewById(R.id.rv_item_tv);
        }
    
        public void bindHolder(String i){
            tv.setText(i);
        }
    }

3.header的布局文件

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

4.实现效果  
![这里写图片描述][SouthEast 3]

--------------------

### 六：这里还是有一个问题在ToolBar隐藏之后，显示header时会有空白 ###

这时，只需修改onScrolled方法就可以了

@Override
                public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                    super.onScrolled(recyclerView, dx, dy);
    
                    int firstViewPosition = ((LinearLayoutManager)recyclerView.getLayoutManager()).findFirstVisibleItemPosition();
                    if (firstViewPosition == 0){
       //当header是FirstVisibleItem并且隐藏了ToolBar时，显示ToolBar
                        if (!controlVisible){
                            animationShow();
                            controlVisible = true;
                        }
                    }else {
    
                        if (controlVisible && scrollDistance > THRESHOLD_OFFSET){
       //手指上滑即Scroll向下滚动的时候，dy为正
                            animationHide();
    
                            //重置使下面的if语句起作用
                            controlVisible = false;
                            scrollDistance = 0;
                        }else if (!controlVisible && scrollDistance < -THRESHOLD_OFFSET){
       //手指下滑即Scroll向上滚动的时候，dy为负
                            animationShow();
                            controlVisible = true;
                            scrollDistance = 0;
                        }
    
                        //当scrollDistance累计到隐藏（显示)ToolBar之后，如果Scroll向下（向上）滚动，则停止对scrollDistance的累加
                        //直到Scroll开始往反方向滚动，再次启动scrollDistance的累加
                        if ((controlVisible && dy > 0) || (!controlVisible && dy < 0)){
                            scrollDistance += dy;
                        }
                    }
                }
            });

最后的效果图：  
![这里写图片描述][SouthEast 4]

[参考][Link 1]

[SouthEast]: /images/20220711/dc108d0e32644b26b70fa226f27c85a8.png
[SouthEast 1]: /images/20220711/79262a869ec14fb196ff46cf5dae82c6.png
[SouthEast 2]: /images/20220711/1dead20ea75c4cf3af68622175033d30.png
[SouthEast 3]: /images/20220711/b17e46ae7e5e463789d8984edc246cd8.png
[SouthEast 4]: /images/20220711/9272adc10812473fabb0a01d42573cbe.png
[Link 1]: https://mzgreen.github.io/2015/02/15/How-to-hideshow-Toolbar-when-list-is-scroling%28part1%29/