java - CollapsingToolbarLayout 在滚动时不折叠

Question

我正在使用 CollapsingToolbarLayout 和一个 viewpager。 Viewpager 由 RecyclerView 组成。但是，当滚动回收器 View 时，工具栏不会折叠。

activity_home.xml

<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:theme="@style/AppTheme.AppBarOverlay">

    <android.support.design.widget.CollapsingToolbarLayout
        android:id="@+id/collapsing_toolbar"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fitsSystemWindows="true"

        app:contentScrim="?attr/colorPrimary"
        app:layout_scrollFlags="scroll|exitUntilCollapsed">
        <ImageView
            android:id="@+id/htab_header"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@drawable/header"
            android:fitsSystemWindows="true"
            android:scaleType="centerCrop"
            app:layout_collapseMode="parallax" />
        <android.support.v7.widget.Toolbar
            android:id="@+id/htab_toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:gravity="top"
            app:layout_collapseMode="pin"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
            app:titleMarginTop="13dp" />

        <android.support.design.widget.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:layout_gravity="bottom"
            app:tabMode="scrollable"/>
    </android.support.design.widget.CollapsingToolbarLayout>

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

<android.support.v4.view.ViewPager
    android:id="@+id/viewpager"
    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="@dimen/fab_margin"
    android:src="@android:drawable/ic_dialog_email" />

fragment_one.xml

<android.support.v7.widget.RecyclerView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/recyclerView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

</android.support.v7.widget.RecyclerView>

HomeActivity.java

import javax.swing.text.View;

public class HomeActivity extends AppCompatActivity {

    private Toolbar toolbar;
    private TabLayout tabLayout;
    private ViewPager viewPager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        toolbar = (Toolbar) findViewById(R.id.htab_toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG).setAction("Action", null)
                        .show();
            }
        });

        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        viewPager = (ViewPager) findViewById(R.id.viewpager);
        setupViewPager(viewPager);

        tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(viewPager);

        final CollapsingToolbarLayout collapsingToolbarLayout = (CollapsingToolbarLayout) findViewById(
                R.id.collapsing_toolbar);
        collapsingToolbarLayout.setTitle("News");
    }

    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        String[] categories = getResources().getStringArray(R.array.categories);
        for (String category : categories) {
            OneFragment fragment = new OneFragment();
            adapter.addFragment(fragment, category);
        }
        viewPager.setAdapter(adapter);
    }
}

Answer 1

只需在工具栏中使用 app:layout_scrollFlags="scroll|enterAlways" 以及如果您还使用协调器布局的良好做法。

  <android.support.v7.widget.Toolbar
       android:id="@+id/htab_toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:gravity="top"
        app:layout_collapseMode="pin"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
        app:titleMarginTop="13dp" 
        app:layout_scrollFlags="scroll|enterAlways">

    </android.support.v7.widget.Toolbar>