嵌套滑动机制 -- CoordinatorLayout

2020-08-22 本文已影响0人 TomyZhang

一、概念

CoordinatorLayout 的类继承关系：

CoordinatorLayout extends ViewGroup implements NestedScrollingParent2,
        NestedScrollingParent3

主要作用：

作为顶层布局；
作为协调子 View 之间交互的容器。

二、使用

1.CoordinatorLayout 与 FloatingActionButton

activity_main.xml：
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/contentView"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <LinearLayout
        android:id="@+id/anchorView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"/>
    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_anchor="@id/anchorView"
        app:layout_anchorGravity="bottom|right"
        android:layout_marginRight="10dp"
        android:layout_marginBottom="10dp"
        android:onClick="onClick"/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

MainActivity：
public class MainActivity extends AppCompatActivity {
    private static final String TAG = MainActivity.class.getSimpleName();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d(TAG, "zwm, onCreate, Target30");
        setContentView(R.layout.activity_main);
    }

    public void onClick(View v) {
        Log.d(TAG, "zwm, onClick");
        switch (v.getId()) {
            case R.id.fab:
                Snackbar.make(findViewById(R.id.contentView), "Hello, Android!", Snackbar.LENGTH_SHORT).show();
                break;
        }
    }
}

日志打印：
2020-09-17 21:15:00.882 9490-9490/com.tomorrow.target30 D/MainActivity: zwm, onCreate, Target30
2020-09-17 21:15:02.823 9490-9490/com.tomorrow.target30 D/MainActivity: zwm, onClick

CoordinatorLayout 提供了两个属性用来设置 FloatingActionButton 的位置：

layout_anchor：设置 FloatingActionButton 的锚点。
layout_anchorGravity：设置 FloatingActionButton 相对锚点的位置。

当 Snackbar 显示和隐藏的时候，CoordinatorLayout 会动态调整 FloatingActionButton 的位置。

2.CoordinatorLayout 与 AppBarLayout

activity_main.xml：
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <com.google.android.material.appbar.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:paddingTop="10dp"
            android:paddingBottom="10dp"
            android:gravity="center"
            android:textSize="30sp"
            android:textColor="@android:color/white"
            android:text="Header"
            android:background="#0000FF"
            app:layout_scrollFlags="scroll"/>
    </com.google.android.material.appbar.AppBarLayout>
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

RecyclerViewAdapter：
public class RecyclerViewAdapter extends RecyclerView.Adapter {
    private List<RecyclerViewBean> mData;
    private LayoutInflater mInflater;

    public RecyclerViewAdapter(Context context, List<RecyclerViewBean> data) {
        this.mData = data;
        this.mInflater = LayoutInflater.from(context);
    }

    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType) {
        switch (viewType) {
            case RecyclerViewBean.TYPE_ITEM:
                return new ContentHolder(mInflater.inflate(R.layout.recyclerview_content_layout, viewGroup, false));
            case RecyclerViewBean.TYPE_TITLE:
                return new TitleHolder(mInflater.inflate(R.layout.recyclerview_title_layout, viewGroup, false));
            default:
                return null;
        }
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder viewHolder, int i) {
        RecyclerViewBean infoBean = mData.get(i);
        int viewType = getItemViewType(i);
        switch (viewType) {
            case RecyclerViewBean.TYPE_ITEM:
                ContentHolder contentHolder = (ContentHolder) viewHolder;
                contentHolder.tvTitle.setText(infoBean.title);
                contentHolder.tvContent.setText(infoBean.content);
                break;
            case RecyclerViewBean.TYPE_TITLE:
                TitleHolder titleHolder = (TitleHolder) viewHolder;
                titleHolder.tvTitle.setText(infoBean.title);
                break;
            default:
                break;
        }
    }

    @Override
    public int getItemCount() {
        return mData == null ? 0 : mData.size();
    }

    @Override
    public int getItemViewType(int position) {
        return mData.get(position).type;
    }

    public static class TitleHolder extends RecyclerView.ViewHolder {
        TextView tvTitle;

        TitleHolder(@NonNull View itemView) {
            super(itemView);
            tvTitle = itemView.findViewById(R.id.tv_title);
        }
    }

    public static class ContentHolder extends RecyclerView.ViewHolder {
        TextView tvTitle;
        TextView tvContent;

        ContentHolder(@NonNull View itemView) {
            super(itemView);
            tvTitle = itemView.findViewById(R.id.tv_title);
            tvContent = itemView.findViewById(R.id.tv_content);
        }
    }
}

RecyclerViewBean：
public class RecyclerViewBean {
    public static final int TYPE_TITLE = 1;
    public static final int TYPE_ITEM = 2;

    public int type;
    public String title;
    public String content;
}

recyclerview_title_layout.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:background="#63BB0B"
    android:layout_height="40dp">
    <TextView
        android:id="@+id/tv_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="15dp"
        android:textSize="20dp"
        android:textStyle="bold"
        android:textColor="#000000"
        android:text="评论"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

recyclerview_content_layout.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
    <TextView
        android:id="@+id/tv_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="15dp"
        android:textColor="#000000"
        android:textSize="16dp"
        android:text="评论"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
    <TextView
        android:id="@+id/tv_content"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="15dp"
        android:layout_marginTop="5dp"
        android:layout_marginBottom="5dp"
        android:textColor="#000000"
        android:textSize="16dp"
        android:text="内容"
        app:layout_constraintTop_toBottomOf="@+id/tv_title"
        app:layout_constraintLeft_toLeftOf="parent" />
    <View
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/tv_content"
        android:layout_marginTop="5dp"
        android:layout_width="0dp"
        android:layout_height="5dp"
        android:background="#686868"/>
</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity：
public class MainActivity extends AppCompatActivity {
    private static final String TAG = MainActivity.class.getSimpleName();
    private RecyclerView mRecyclerView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d(TAG, "zwm, onCreate, Target30");
        setContentView(R.layout.activity_main);
        initRecyclerView();
    }

    private void initRecyclerView() {
        mRecyclerView = findViewById(R.id.recyclerview);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        List<RecyclerViewBean> data = getCommentData();
        RecyclerViewAdapter rvAdapter = new RecyclerViewAdapter(this, data);
        mRecyclerView.setAdapter(rvAdapter);
    }

    private List<RecyclerViewBean> getCommentData() {
        List<RecyclerViewBean> commentList = new ArrayList<>();
        RecyclerViewBean titleBean = new RecyclerViewBean();
        titleBean.type = RecyclerViewBean.TYPE_TITLE;
        titleBean.title = "评论列表";
        commentList.add(titleBean);
        for (int i = 0; i < 40; i++) {
            RecyclerViewBean contentBean = new RecyclerViewBean();
            contentBean.type = RecyclerViewBean.TYPE_ITEM;
            contentBean.title = "评论标题" + i;
            contentBean.content = "评论内容" + i;
            commentList.add(contentBean);
        }
        return commentList;
    }
}

CoordinatorLayout 中可滚动的 View（如上例中 RecyclerView），需要设置以下属性：
```
app:layout_behavior="@string/appbar_scrolling_view_behavior"
```
AppBarLayout 中的 View（如上例中 TextView），如要想要滚动到屏幕外，必须设置以下属性：
```
app:layout_scrollFlags="scroll"
```
scroll 的效果为：隐藏的时候，先整体向上滚动，直到 AppBarLayout 完全隐藏，再开始滚动 Scrolling View；显示的时候，直到 Scrolling View 顶部完全出现后，再开始滚动 AppBarLayout 到完全显示。

除了 scroll，还有下面几个取值，这些属性都必须与 scroll 一起使用 "|" 运算符：

enterAlways：与 scroll 类似（scroll|enterAlways），只不过向下滚动先让 AppBarLayout 完全显示，再滚动 Scrolling View：

activity_main.xml：
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <com.google.android.material.appbar.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:paddingTop="10dp"
            android:paddingBottom="10dp"
            android:gravity="center"
            android:textSize="30sp"
            android:textColor="@android:color/white"
            android:text="Header"
            android:background="#0000FF"
            app:layout_scrollFlags="scroll|enterAlways"/>
    </com.google.android.material.appbar.AppBarLayout>
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

enterAlwaysCollapsed：需要和 enterAlways 一起使用（scroll|enterAlways|enterAlwaysCollapsed），和 enterAlways 不一样的是，不会在 AppBarLayout 完全显示后才滚动 Scrolling View，而是先滚动 AppBarLayout 到最小高度，然后滚动 Scrolling View 直到顶部完全出现，最后再滚动 AppBarLayout 到完全显示。注意：需要定义 View 的最小高度（minHeight）才有效果：

activity_main.xml：
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <com.google.android.material.appbar.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:paddingTop="10dp"
            android:paddingBottom="10dp"
            android:gravity="center"
            android:textSize="30sp"
            android:textColor="@android:color/white"
            android:text="Header"
            android:background="#0000FF"
            android:minHeight="20dp"
            app:layout_scrollFlags="scroll|enterAlways|enterAlwaysCollapsed"/>
    </com.google.android.material.appbar.AppBarLayout>
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

exitUntilCollapsed：定义了 AppBarLayout 消失的规则。发生向上滚动事件时，AppBarLayout 向上滚动退出直至最小高度（minHeight），然后 Scrolling View 开始滚动。也就是 AppBarLayout 不会完全退出屏幕：

activity_main.xml：
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <com.google.android.material.appbar.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:paddingTop="10dp"
            android:paddingBottom="10dp"
            android:gravity="center"
            android:textSize="30sp"
            android:textColor="@android:color/white"
            android:text="Header"
            android:background="#0000FF"
            android:minHeight="20dp"
            app:layout_scrollFlags="scroll|exitUntilCollapsed"/>
    </com.google.android.material.appbar.AppBarLayout>
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

enterAlwaysCollapsed 与 exitUntilCollapsed 在实际的使用中，更多的是与 CollapsingToolbarLayout 一起使用。

3.CoordinatorLayout 与 CollapsingToolbarLayout

CollapsingToolbarLayout 继承自 FrameLayout，它是用来实现 Toolbar 的折叠效果，一般它的直接子 View 是 Toolbar，当然也可以是其它类型的 View：

activity_main.xml：
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <com.google.android.material.appbar.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="150dp">
        <com.google.android.material.appbar.CollapsingToolbarLayout
            android:id="@+id/collapsingToolbarLayout"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:contentScrim="#0000FF"
            app:layout_scrollFlags="scroll|enterAlways">
            <androidx.appcompat.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="50dp"
                app:layout_collapseMode="pin"
                app:navigationIcon="@mipmap/ic_launcher_round"
                app:title="Hello, Android!"/>
        </com.google.android.material.appbar.CollapsingToolbarLayout>
    </com.google.android.material.appbar.AppBarLayout>
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

app:contentScrim：表示 CollapsingToolbarLayout 折叠之后的“前景色”，我们看到 Toolbar 的变色，其实是因为前景色遮挡了而已。
app:layout_scrollFlags="scroll|enterAlways" 效果为：向下滚动先让 AppBarLayout 完全显示，再滚动 Scrolling View。
app:layout_collapseMode="pin" 确保 CollapsingToolbarLayout 折叠完成之前，Toolbar 一直固定在顶部不动。

使用 app:layout_scrollFlags="scroll|enterAlways|exitUntilCollapsed" 及 app:layout_collapseMode="pin"，让 Toolbar 一直固定在顶部不动：

activity_main.xml：
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <com.google.android.material.appbar.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="150dp">
        <com.google.android.material.appbar.CollapsingToolbarLayout
            android:id="@+id/collapsingToolbarLayout"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:contentScrim="#0000FF"
            app:layout_scrollFlags="scroll|enterAlways|exitUntilCollapsed">
            <androidx.appcompat.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="50dp"
                app:layout_collapseMode="pin"
                app:title="Hello, Android!"
                app:navigationIcon="@mipmap/ic_launcher"/>
        </com.google.android.material.appbar.CollapsingToolbarLayout>
    </com.google.android.material.appbar.AppBarLayout>
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

使用 app:layout_collapseMode="parallax"、app:layout_scrollFlags="scroll|enterAlways|exitUntilCollapsed" 及 app:layout_collapseMode="pin"，产生视差效果：

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <com.google.android.material.appbar.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="150dp">
        <com.google.android.material.appbar.CollapsingToolbarLayout
            android:id="@+id/collapsingToolbarLayout"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:contentScrim="#0000FF"
            app:layout_scrollFlags="scroll|enterAlways|exitUntilCollapsed">
            <ImageView
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:src="@drawable/image"
                android:scaleType="centerCrop"
                app:layout_collapseParallaxMultiplier="0.9"
                app:layout_collapseMode="parallax"/>
            <androidx.appcompat.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="50dp"
                app:layout_collapseMode="pin"
                app:title="Hello, Android!"
                app:navigationIcon="@mipmap/ic_launcher"/>
        </com.google.android.material.appbar.CollapsingToolbarLayout>
    </com.google.android.material.appbar.AppBarLayout>
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

三、原理

CoordinatorLayout 的核心是 Behavior，Behavior 提供了二十多个空方法给使用者来重写，主要分为四类：

与 Touch 事件相关的方法
与 NestedScroll 相关的方法
与控件依赖相关的方法
其他方法，如测量和布局等

重要概念：

child，是一个 View，是该 Behavior 所要操作的对象
dependency，也是一个 View，是 child 的依赖对象，也是该 Behavior 对 child 进行操作的根据

重要方法：

layoutDependsOn

public boolean layoutDependsOn(@NonNull CoordinatorLayout parent, @NonNull V child,
                @NonNull View dependency)

它会被 Behavior 的 LayoutParams 的 dependsOn 方法调用：

boolean dependsOn(CoordinatorLayout parent, View child, View dependency) {
  return dependency == mAnchorDirectChild
          || shouldDodge(dependency, ViewCompat.getLayoutDirection(parent))
          || (mBehavior != null && mBehavior.layoutDependsOn(parent, child, dependency));
}

dependsOn 方法就是用来确定依赖关系的。最简单的确定依赖关系的方法是重写 layoutDependsOn 方法，并在一定条件下返回 true 即可。

onDependentViewChanged

public boolean onDependentViewChanged(@NonNull CoordinatorLayout parent, @NonNull V child, @NonNull View dependency)

当 dependency 发生改变的时候，这个方法会调用。

自定义简单的 Behavior：

activity_main.xml：
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <Button
        android:id="@+id/btn"
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:background="#0000FF"
        android:textAllCaps="false"
        android:textColor="#FFFFFF"
        android:text="child"
        app:layout_behavior="com.tomorrow.target30.MyBehavior" />
    <com.tomorrow.target30.TempView
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:background="#CC88CC"
        android:gravity="center"
        android:textColor="#FFFFFF"
        android:text="dependency"
        android:clickable="true"/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

MyBehavior：
public class MyBehavior extends CoordinatorLayout.Behavior<Button> {
    private static final String TAG = MyBehavior.class.getSimpleName();
    private int mWidth;

    public MyBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);
        DisplayMetrics display = context.getResources().getDisplayMetrics();
        mWidth = display.widthPixels;
    }

    @Override
    public boolean layoutDependsOn(CoordinatorLayout parent, Button child, View dependency) {
        Log.d(TAG, "zwm, layoutDependsOn, parent: " + parent + ", child: " + child + ", dependency: " + dependency);
        //如果dependency是TempView的实例，说明它就是我们所需要的Dependency
        return dependency instanceof TempView;
    }

    //每次dependency位置发生变化，都会执行onDependentViewChanged方法
    @Override
    public boolean onDependentViewChanged(CoordinatorLayout parent, Button btn, View dependency) {
        Log.d(TAG, "zwm, onDependentViewChanged, parent: " + parent + ", btn: " + btn + ", dependency: " + dependency);
        //根据dependency的位置，设置Button的位置
        int top = dependency.getTop();
        int left = dependency.getLeft();
        int x = mWidth - left - btn.getWidth();
        int y = top;
        setPosition(btn, x, y);
        return true;
    }

    private void setPosition(View v, int x, int y) {
        CoordinatorLayout.MarginLayoutParams layoutParams = (CoordinatorLayout.MarginLayoutParams) v.getLayoutParams();
        layoutParams.leftMargin = x;
        layoutParams.topMargin = y;
        v.setLayoutParams(layoutParams);
    }
}

TempView：
public class TempView extends TextView {
    private static final String TAG = TempView.class.getSimpleName();
    private int mTouchStartX;
    private int mTouchStartY;

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

    public TempView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        Log.d(TAG, "zwm, onTouchEvent action: " + event.getAction());
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                mTouchStartX = (int) event.getX();
                mTouchStartY = (int) event.getY();
                Log.d(TAG, "zwm, mTouchStartX: " + mTouchStartX + ", mTouchStartY: " + mTouchStartY);
                break;
            case MotionEvent.ACTION_MOVE:
                int dx = (int) event.getX() - mTouchStartX;
                int dy = (int) event.getY() - mTouchStartY;
                Log.d(TAG, "zwm, dx: " + dx + ", dy: " + dy);
                setPosition(dx, dy);
                break;
            case MotionEvent.ACTION_UP:
                break;
        }
        return super.onTouchEvent(event);
    }

    private void setPosition(int dx, int dy) {
        CoordinatorLayout.MarginLayoutParams layoutParams = (CoordinatorLayout.MarginLayoutParams) getLayoutParams();
        layoutParams.leftMargin += dx;
        layoutParams.topMargin += dy;
        setLayoutParams(layoutParams);
    }
}

MainActivity：
public class MainActivity extends AppCompatActivity {
    private static final String TAG = MainActivity.class.getSimpleName();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d(TAG, "zwm, onCreate, Target30");
        setContentView(R.layout.activity_main);
    }
}

日志打印：
2020-09-21 12:14:29.337 32265-32265/com.tomorrow.target30 D/MainActivity: zwm, onCreate, Target30
2020-09-21 12:14:29.379 32265-32265/com.tomorrow.target30 D/MyBehavior: zwm, layoutDependsOn, parent: androidx.coordinatorlayout.widget.CoordinatorLayout{88636b V.E...... ......I. 0,0-0,0}, child: androidx.appcompat.widget.AppCompatButton{7dd18ba VFED..C.. ......ID 0,0-0,0 #7f080057 app:id/btn}, dependency: com.tomorrow.target30.TempView{81f1ec8 VFED..C.. ......ID 0,0-0,0}
2020-09-21 12:14:29.397 32265-32265/com.tomorrow.target30 D/MyBehavior: zwm, layoutDependsOn, parent: androidx.coordinatorlayout.widget.CoordinatorLayout{88636b V.E...... ......I. 0,0-0,0}, child: androidx.appcompat.widget.AppCompatButton{7dd18ba VFED..C.. ......ID 0,0-0,0 #7f080057 app:id/btn}, dependency: com.tomorrow.target30.TempView{81f1ec8 VFED..C.. ......ID 0,0-0,0}
2020-09-21 12:14:29.398 32265-32265/com.tomorrow.target30 D/MyBehavior: zwm, layoutDependsOn, parent: androidx.coordinatorlayout.widget.CoordinatorLayout{88636b V.E...... ......ID 0,0-1080,2232}, child: androidx.appcompat.widget.AppCompatButton{7dd18ba VFED..C.. ......ID 0,0-264,150 #7f080057 app:id/btn}, dependency: com.tomorrow.target30.TempView{81f1ec8 VFED..C.. ......ID 0,0-226,150}
2020-09-21 12:14:29.398 32265-32265/com.tomorrow.target30 D/MyBehavior: zwm, onDependentViewChanged, parent: androidx.coordinatorlayout.widget.CoordinatorLayout{88636b V.E...... ......ID 0,0-1080,2232}, btn: androidx.appcompat.widget.AppCompatButton{7dd18ba VFED..C.. ......ID 0,0-264,150 #7f080057 app:id/btn}, dependency: com.tomorrow.target30.TempView{81f1ec8 VFED..C.. ......ID 0,0-226,150}
2020-09-21 12:14:29.408 32265-32265/com.tomorrow.target30 D/MyBehavior: zwm, layoutDependsOn, parent: androidx.coordinatorlayout.widget.CoordinatorLayout{88636b V.E...... ........ 0,0-1080,2232}, child: androidx.appcompat.widget.AppCompatButton{7dd18ba VFED..C.. ........ 0,0-264,150 #7f080057 app:id/btn}, dependency: com.tomorrow.target30.TempView{81f1ec8 VFED..C.. ........ 0,0-226,150}
2020-09-21 12:14:33.048 32265-32265/com.tomorrow.target30 D/TempView: zwm, onTouchEvent action: 0
2020-09-21 12:14:33.048 32265-32265/com.tomorrow.target30 D/TempView: zwm, mTouchStartX: 160, mTouchStartY: 126
2020-09-21 12:14:33.093 32265-32265/com.tomorrow.target30 D/TempView: zwm, onTouchEvent action: 2
2020-09-21 12:14:33.093 32265-32265/com.tomorrow.target30 D/TempView: zwm, dx: 1, dy: 0
2020-09-21 12:14:33.095 32265-32265/com.tomorrow.target30 D/MyBehavior: zwm, layoutDependsOn, parent: androidx.coordinatorlayout.widget.CoordinatorLayout{88636b V.E...... ......I. 0,0-1080,2232}, child: androidx.appcompat.widget.AppCompatButton{7dd18ba VFED..C.. ........ 816,0-1080,150 #7f080057 app:id/btn}, dependency: com.tomorrow.target30.TempView{81f1ec8 VFED..C.. ...p..I. 0,0-226,150}
2020-09-21 12:14:33.097 32265-32265/com.tomorrow.target30 D/MyBehavior: zwm, layoutDependsOn, parent: androidx.coordinatorlayout.widget.CoordinatorLayout{88636b V.E...... ......ID 0,0-1080,2232}, child: androidx.appcompat.widget.AppCompatButton{7dd18ba VFED..C.. ........ 816,0-1080,150 #7f080057 app:id/btn}, dependency: com.tomorrow.target30.TempView{81f1ec8 VFED..C.. ...p..ID 1,0-227,150}
2020-09-21 12:14:33.097 32265-32265/com.tomorrow.target30 D/MyBehavior: zwm, onDependentViewChanged, parent: androidx.coordinatorlayout.widget.CoordinatorLayout{88636b V.E...... ......ID 0,0-1080,2232}, btn: androidx.appcompat.widget.AppCompatButton{7dd18ba VFED..C.. ........ 816,0-1080,150 #7f080057 app:id/btn}, dependency: com.tomorrow.target30.TempView{81f1ec8 VFED..C.. ...p..ID 1,0-227,150}