定義behavior

 import android.content.Context;
 import android.os.Build;
 import android.support.design.widget.CoordinatorLayout;
 import android.support.design.widget.FloatingActionButton;
 import android.support.v4.view.ViewCompat;
 import android.support.v4.view.ViewPropertyAnimatorListener;
 import android.support.v4.view.animation.FastOutSlowInInterpolator;
 import android.util.AttributeSet;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.animation.Interpolator;
 
 /**
  * Created by 070 on 2017/6/29.
  */
 
 public class ScrollAwareFABBehavior extends FloatingActionButton.Behavior {
 
     private static final Interpolator INTERPOLATOR = new FastOutSlowInInterpolator();
     private boolean mIsAnimatingOut = false;
 
     public ScrollAwareFABBehavior(Context context, AttributeSet attrs) {
         super();
     }
 
     @Override
     public boolean onStartNestedScroll(final CoordinatorLayout coordinatorLayout, final FloatingActionButton child,
                                        final View directTargetChild, final View target, final int nestedScrollAxes) {
 
         return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL
                 || super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target, nestedScrollAxes);
     }
 
     @Override
     public void onNestedScroll(final CoordinatorLayout coordinatorLayout, final FloatingActionButton child,
                                final View target, final int dxConsumed, final int dyConsumed,
                                final int dxUnconsumed, final int dyUnconsumed) {
         super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed);
         if (dyConsumed > 0 && !this.mIsAnimatingOut && child.getVisibility() == View.VISIBLE) {
             animateOut(child);
         } else if (dyConsumed < 0 && child.getVisibility() != View.VISIBLE) {
             animateIn(child);
         }
     }
 
     private void animateOut(final FloatingActionButton button) {
         if (Build.VERSION.SDK_INT >= 14) {
             ViewCompat.animate(button).translationY(button.getHeight() + getMarginBottom(button)).setInterpolator(INTERPOLATOR).withLayer()
                     .setListener(new ViewPropertyAnimatorListener() {
                         public void onAnimationStart(View view) {
                             ScrollAwareFABBehavior.this.mIsAnimatingOut = true;
                         }
 
                         public void onAnimationCancel(View view) {
                             ScrollAwareFABBehavior.this.mIsAnimatingOut = false;
                         }
 
                         public void onAnimationEnd(View view) {
                             ScrollAwareFABBehavior.this.mIsAnimatingOut = false;
                             view.setVisibility(View.INVISIBLE);
                         }
                     }).start();
         } else {
 
         }
     }
 
     private void animateIn(FloatingActionButton button) {
         button.setVisibility(View.VISIBLE);
         if (Build.VERSION.SDK_INT >= 14) {
             ViewCompat.animate(button).translationY(0)
                     .setInterpolator(INTERPOLATOR).withLayer().setListener(null)
                     .start();
         } else {
 
         }
     }
 
     private int getMarginBottom(View v) {
         int marginBottom = 0;
         final ViewGroup.LayoutParams layoutParams = v.getLayoutParams();
         if (layoutParams instanceof ViewGroup.MarginLayoutParams) {
             marginBottom = ((ViewGroup.MarginLayoutParams) layoutParams).bottomMargin;
         }
         return marginBottom;
     }
 }

在布局文件中應(yīng)用

 <?xml version="1.0" encoding="utf-8"?>
 <android.support.design.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">
 
     <android.support.design.widget.AppBarLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         app:theme="@style/AppTheme.AppBarOverlay">
 
         <android.support.v7.widget.Toolbar
             android:id="@+id/toolbar"
             android:layout_width="match_parent"
             android:layout_height="?attr/actionBarSize"
             app:popupTheme="@style/AppTheme.PopupOverlay" />
     </android.support.design.widget.AppBarLayout>
 
     <android.support.v7.widget.RecyclerView
         android:id="@+id/recycle"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         app:layout_behavior="@string/appbar_scrolling_view_behavior" />
 
     <android.support.design.widget.FloatingActionButton
         android:id="@+id/fab"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_gravity="bottom|end"
         android:layout_margin="16dp"
         android:src="@mipmap/abc_ic_ab_back_top"
         app:layout_behavior="com.example.a070.demo.behavior.ScrollAwareFABBehavior"
         app:layout_scrollFlags="scroll|enterAlways|snap" />
 
 </android.support.design.widget.CoordinatorLayout>