Android使用Material Design自带CoordinatorLayout+AppBarLayout+CollapsingToolbarLayout+Toolbar组件实现标题栏滑动渐变色

效果图如下：

1.首先要在app.gradle文件中添加

implementation 'com.android.support:design:26.1.0'

2.布局文件如下：

<?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:id="@+id/appBar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

        <android.support.design.widget.CollapsingToolbarLayout
            android:layout_width="match_parent"
            android:layout_height="150dp"
            app:layout_scrollFlags="scroll|exitUntilCollapsed">
            <com.youth.banner.Banner
                android:id="@+id/banner"
                android:layout_width="match_parent"
                android:layout_height="150dp" />
            <android.support.v7.widget.Toolbar
                android:layout_width="match_parent"
                android:layout_height="50dp"
                app:contentInsetStart="0dp"
                app:layout_collapseMode="pin">
                <LinearLayout
                    android:id="@+id/ll_top"
                    android:layout_width="match_parent"
                    android:layout_height="50dp"
                    android:gravity="center_vertical"
                    android:orientation="horizontal"
                    >

                    <LinearLayout
                        android:id="@+id/ll_search"
                        android:layout_width="0dp"
                        android:layout_height="wrap_content"
                        android:layout_weight="3"
                        android:layout_marginLeft="@dimen/text_layout_10_dp"
                        android:background="@drawable/sousuo_yuanjiao"
                        android:gravity="center_vertical"
                        android:paddingBottom="3dp"
                        android:paddingLeft="@dimen/text_layout_15_dp"
                        android:paddingRight="@dimen/text_layout_10_dp"
                        android:layout_centerVertical="true"
                        android:paddingTop="3dp">

                        <TextView
                            android:layout_width="wrap_content"
                            android:layout_height="24dp"
                            android:layout_alignBottom="@+id/imageView1"
                            android:layout_toEndOf="@+id/imageView1"
                            android:layout_toRightOf="@+id/imageView1"
                            android:layout_weight="2"
                            android:drawableLeft="@drawable/ic_search_black"
                            android:drawablePadding="@dimen/text_layout_10_dp"
                            android:gravity="center_vertical"
                            android:text="请输入食品、药品、食谱名称"
                            android:textColor="@color/tv333"
                            android:textSize="@dimen/text_size_13_sp" />
                    </LinearLayout>

                    <RelativeLayout
                        android:layout_width="0dp"
                        android:layout_height="match_parent"
                        android:layout_weight="1"
                        >
                        <ImageView
                            android:id="@+id/iv_message"
                            android:layout_width="wrap_content"
                            android:layout_height="match_parent"
                            android:scaleType="centerInside"
                            android:layout_centerVertical="true"
                            android:layout_alignParentRight="true"
                            android:paddingRight="@dimen/text_layout_10_dp"
                            android:src="@drawable/ic_message" />
                    </RelativeLayout>


                </LinearLayout>
            </android.support.v7.widget.Toolbar>
        </android.support.design.widget.CollapsingToolbarLayout>
    </android.support.design.widget.AppBarLayout>

    <android.support.v4.widget.NestedScrollView
        android:id="@+id/scrollView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        android:scrollbars="none">


        <!-自己的内容-->
    </android.support.v4.widget.NestedScrollView>

</android.support.design.widget.CoordinatorLayout>

3.具体实现代码：

appBarLayout.addOnOffsetChangedListener(new AppBarLayout.OnOffsetChangedListener() {
            @Override
            public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
                int toolbarHeight = appBarLayout.getTotalScrollRange();
                int dy = Math.abs(verticalOffset);
                if (dy <= toolbarHeight) {
                    float scale = (float) dy / toolbarHeight;
                    float alpha = scale * 255;
                    ll_top.setBackgroundColor(Color.argb((int) alpha, 54, 161, 70));
                }
            }
        });