这次带来的是结合CoordinatorLayout、AppBarLayout、CollapsingToolbarLayout和FloatingActionButton打造炫酷的视觉差效果。

实现步骤

一：需要在主题文件中将Activity的标题栏去掉

二：编写Activity的布局文件

<?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"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <android.support.design.widget.CollapsingToolbarLayout
            android:layout_width="match_parent"
            app:contentScrim="@color/colorPrimary"
            app:expandedTitleMarginStart="15dp"
            app:collapsedTitleTextAppearance="@style/ToolbarTextStyle" //设置收缩时的标题样式
            app:expandedTitleTextAppearance="@style/CollapseexpandedTextStyle" //设置展开时的标题样式
            app:layout_scrollFlags="scroll|exitUntilCollapsed" //这个属性使得CollapsingToolbarLayout在滑动的时候显示隐藏
            android:layout_height="wrap_content">
            <ImageView
                android:layout_width="match_parent"
                android:src="@mipmap/bg"
                android:scaleType="fitXY"
                app:layout_collapseMode="parallax" //这个属性使得ImageView在CollapsingToolbarLayout展开的时候显示
                android:layout_height="200dp" />
            <android.support.v7.widget.Toolbar
                android:layout_width="match_parent"
                android:id="@+id/toolbar"
                app:layout_collapseMode="pin" //这个属性使得Toolbar在CollapsingToolbarLayout收缩的时候显示
                android:layout_height="50dp">
            </android.support.v7.widget.Toolbar>
        </android.support.design.widget.CollapsingToolbarLayout>
    </android.support.design.widget.AppBarLayout>
    <android.support.v7.widget.RecyclerView
        android:layout_width="match_parent"
        android:id="@+id/recycle"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" //这个属性是让控件在AppBarLayout下边
        android:layout_height="match_parent">

    </android.support.v7.widget.RecyclerView>
    <android.support.design.widget.FloatingActionButton
        android:layout_width="wrap_content"
        android:src="@drawable/ic_logo"
        app:layout_anchor="@id/appbar" //这个属性是让FloatingActionButton以AppBarLayout为锚点，同时这也是使FloatingActionButton实现显示隐藏的关键
        app:layout_anchorGravity="bottom|end" //在AppBarLayout的右下方
        app:borderWidth="0dp"
        app:rippleColor="#E23B74"
        app:elevation="6dp"
        app:pressedTranslationZ="12dp"
        android:clickable="true"
        android:layout_marginRight="10dp"
        android:layout_height="wrap_content" />
</android.support.design.widget.CoordinatorLayout>

style/ToolbarTextStyle和style/CollapseexpandedTextStyle

 <style name="CollapseexpandedTextStyle" parent="TextAppearance.AppCompat">
        <item name="android:textColor">#fff</item>
        <item name="android:textSize">23sp</item>
    </style>
    <style name="ToolbarTextStyle" parent="TextAppearance.AppCompat">
        <item name="android:textColor">#fff</item>
        <item name="android:textSize">18sp</item>
</style>

三：编写Activity代码

public class MainActivity extends AppCompatActivity {
    Toolbar toolbar;
    RecyclerView recyclerView;
    AppBarLayout appBarLayout;
    private BaseQuickAdapter<String, BaseViewHolder> baseQuickAdapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        toolbar=findViewById(R.id.toolbar);
        appBarLayout=findViewById(R.id.appbar);
        toolbar.setTitle("我是标题");
        setSupportActionBar(toolbar);
//        设置条目（可以省略）========================
        recyclerView=findViewById(R.id.recycle);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        final ArrayList<String> strings = new ArrayList<>();
        for(int x=0;x<10;x++){
            strings.add("我是条目"+x);
        }
        baseQuickAdapter = new BaseQuickAdapter<String, BaseViewHolder>(R.layout.item, strings) {
            @Override
            protected void convert(BaseViewHolder helper, String item) {
                helper.setText(R.id.tv_title, item);
            }
        };
        baseQuickAdapter.openLoadAnimation(BaseQuickAdapter.SLIDEIN_LEFT);
        baseQuickAdapter.setOnItemChildClickListener(new BaseQuickAdapter.OnItemChildClickListener() {
            @Override
            public void onItemChildClick(BaseQuickAdapter adapter, View view, int position) {
                    
            }
        });
        recyclerView.setAdapter(baseQuickAdapter);
//        ==================================================
        appBarLayout.addOnOffsetChangedListener(new AppBarStateChangeListener() {
            @Override
            public void onStateChanged(AppBarLayout appBarLayout, State state) {
                if( state == State.EXPANDED ) {
                    //展开状态
                    toolbar.setNavigationIcon(R.drawable.ic_backfour);
                }else if(state == State.COLLAPSED){
                    //折叠状态
                    toolbar.setNavigationIcon(R.drawable.ic_back);
                }else {
                    //中间状态
                    toolbar.setNavigationIcon(R.drawable.ic_back);
                }
            }
        });

    }
    private abstract static class AppBarStateChangeListener implements AppBarLayout.OnOffsetChangedListener {
        public enum State {
            EXPANDED,
            COLLAPSED,
            IDLE
        }

        private State mCurrentState = State.IDLE;
        @Override
        public final void onOffsetChanged(AppBarLayout appBarLayout, int i) {
            if (i == 0) {
                if (mCurrentState != State.EXPANDED) {
                    onStateChanged(appBarLayout, State.EXPANDED);
                }
                mCurrentState = State.EXPANDED;
            } else if (Math.abs(i) >= appBarLayout.getTotalScrollRange()) {
                if (mCurrentState != State.COLLAPSED) {
                    onStateChanged(appBarLayout, State.COLLAPSED);
                }
                mCurrentState = State.COLLAPSED;
            } else {
                if (mCurrentState != State.IDLE) {
                    onStateChanged(appBarLayout, State.IDLE);
                }
                mCurrentState = State.IDLE;
            }
        }
        public abstract void onStateChanged(AppBarLayout appBarLayout, State state);
    }
  }