可折叠式标题栏

CollapsingToolbarLayout

一种华丽的效果布局，不能单独存在，只能作为AppBarLayout字布局来使用

示例代码

activity_collapsing_toolbar.xml

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    tools:context=".chapter12.CollapsingToolbarActivity"
    android:fitsSystemWindows="true">
    <android.support.design.widget.AppBarLayout
        android:id="@+id/ct_abl"
        android:layout_width="match_parent"
        android:layout_height="250dp"
        android:fitsSystemWindows="true">
        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/ct_ctl"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
            app:contentScrim="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|exitUntilCollapsed"
            android:fitsSystemWindows="true">
            <ImageView
                android:id="@+id/ct_iv"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:scaleType="centerCrop"
                app:layout_collapseMode="parallax"
                android:fitsSystemWindows="true"/>
            <android.support.v7.widget.Toolbar
                android:id="@+id/ct_tb"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                app:layout_collapseMode="pin">

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

    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical">
            <android.support.v7.widget.CardView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginBottom="15dp"
                android:layout_marginLeft="15dp"
                android:layout_marginRight="15dp"
                android:layout_marginTop="35dp"
                app:cardCornerRadius="4dp">
                <TextView
                    android:id="@+id/ct_tv"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_margin="10dp"/>
            </android.support.v7.widget.CardView>
        </LinearLayout>
    </android.support.v4.widget.NestedScrollView>

    <android.support.design.widget.FloatingActionButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:src="@drawable/ic_launcher_background"
        app:layout_anchor="@id/ct_abl"
        app:layout_anchorGravity="bottom|end"/>

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

CollapsingToolbarActivity.java

public class CollapsingToolbarActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_collapsing_toolbar);

        Intent intent = getIntent();
        String name = "Apple";
        int imgId = R.drawable.apple;
        Toolbar toolbar = findViewById(R.id.ct_tb);
        CollapsingToolbarLayout layout = findViewById(R.id.ct_ctl);
        ImageView iv = findViewById(R.id.ct_iv);
        TextView tv = findViewById(R.id.ct_tv);
        setSupportActionBar(toolbar);
        ActionBar actionBar = getSupportActionBar();
        if (actionBar != null) {
            actionBar.setDisplayHomeAsUpEnabled(true);
        }
        layout.setTitle(name);
        Glide.with(this).load(imgId).into(iv);
        String content = generateFruitContent(name);
        tv.setText(content);
    }

    private String generateFruitContent(String name) {
        StringBuilder sb = new StringBuilder();
        for (int i=0; i<50; i++) {
            sb.append(name);
        }
        return sb.toString();
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case android.R.id.home:
                finish();
                return true;
        }
        return super.onOptionsItemSelected(item);
    }
}