在MVVM体系结构中使用Tab布局和数据绑定库

Question

我正在开发一个具有标签布局作为图像的应用程序.

我想将MVVM架构与数据绑定库一起使用,但我是这个框架的新手.

我可以通过使用ViewPager作为此示例的常规设置选项卡布局而不使用MVVM来执行此操作.

没有MVVM和数据绑定的常规选项卡布局:

activity_main.xml中:

<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"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        app:layout_scrollFlags="scroll|enterAlways"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />

    <android.support.design.widget.TabLayout
        android:id="@+id/tabs"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:tabMode="fixed"
        app:tabGravity="fill"/>
</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"  />

MainActivity.java:

public class MainActivity 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.toolbar);
    setSupportActionBar(toolbar);

    getSupportActionBar().setDisplayHomeAsUpEnabled(true);

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

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

private void setupViewPager(ViewPager viewPager) {
    ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
    adapter.addFragment(new OneFragment(), "ONE");
    adapter.addFragment(new TwoFragment(), "TWO");
    adapter.addFragment(new ThreeFragment(), "THREE");
    viewPager.setAdapter(adapter);
}

class ViewPagerAdapter extends FragmentPagerAdapter {
    private final List<Fragment> mFragmentList = new ArrayList<>();
    private final List<String> mFragmentTitleList = new ArrayList<>();

    public ViewPagerAdapter(FragmentManager manager) {
        super(manager);
    }

    @Override
    public Fragment getItem(int position) {
        return mFragmentList.get(position);
    }

    @Override
    public int getCount() {
        return mFragmentList.size();
    }

    public void addFragment(Fragment fragment, String title) {
        mFragmentList.add(fragment);
        mFragmentTitleList.add(title);
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mFragmentTitleList.get(position);
    }
}

}

MVVM中的标签布局:

将MVVM与数据绑定库一起使用时,我们必须使用选项卡布局视图的视图模型.

我不知道如何在XML和视图模型中设置标签布局.如何使用数据绑定库处理诸如"点击布局的一个选项卡"之类的事件

有没有使用数据绑定库在MVVM中使用Tab布局的示例？

谢谢你的帮助.

Answer 1

主要活动 -

public class MainActivity extends Activity 
{
    @Override
    protected void onCreate(@Nullable final Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        App.get(this).component().inject(this);
        ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);
        binding.setHandler(this);
        binding.setManager(getSupportFragmentManager());
    }

    @BindingAdapter({"bind:handler"})
    public static void bindViewPagerAdapter(final ViewPager view, final MainActivity activity)
    {
        final MainActionsAdapter adapter = new MainActionsAdapter(view.getContext(), activity.getSupportFragmentManager());
        view.setAdapter(adapter);
    }

    @BindingAdapter({"bind:pager"})
    public static void bindViewPagerTabs(final TabLayout view, final ViewPager pagerView)
    {
        view.setupWithViewPager(pagerView, true);
    }

}

xml -

<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:fresco="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <data>

        <import type="android.view.View" />

        <variable
            name="handler"
            type="com.ui.main.MainActivity" />

        <variable
            name="manager"
            type="android.support.v4.app.FragmentManager" />
    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:animateLayoutChanges="true"
            app:title="@string/app_name"
            app:titleMarginStart="8dp" />

        <android.support.design.widget.TabLayout
            android:id="@+id/tab_layout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:pager="@{(pager)}">
        </android.support.design.widget.TabLayout>

        <android.support.v4.view.ViewPager
            android:id="@+id/pager"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:handler="@{handler}" />

    </LinearLayout>

</layout>

适配器 -

public class MainSectionsAdapter extends FragmentPagerAdapter
{
    private static final int CONTACTS = 0;
    private static final int CALLS = 1;
    private static final int CHATS = 2;

    private static final int[] TABS = new int[]{CONTACTS, CALLS, CHATS};

    private Context mContext;

    public MainSectionsAdapter(final Context context, final FragmentManager fm)
    {
        super(fm);
        mContext = context.getApplicationContext();
    }

    @Override
    public Fragment getItem(int position)
    {
        switch (TABS[position])
        {
            case CONTACTS:
                return ContactsFragment.newInstance();
            case CALLS:
                return CallsFragment.newInstance();
            case CHATS:
                return ChatsFragment.newInstance();
        }
        return null;
    }

    @Override
    public int getCount()
    {
        return TABS.length;
    }

    @Override
    public CharSequence getPageTitle(int position)
    {
        switch (TABS[position])
        {
            case CONTACTS:
                return mContext.getResources().getString(R.string.contacts);
            case CALLS:
                return mContext.getResources().getString(R.string.calls);
            case CHATS:
                return mContext.getResources().getString(R.string.chats);
        }
        return null;
    }
}