高德天气应用开发之四：android ViewPager实现左右页面滑动切换

【版权说明】

1. 请支持原创，转载请注明出处：https://blog.csdn.net/cbk861110/article/details/86665564

2. 项目源码请移步：https://github.com/caobaokang419/WeatherApp（欢迎Github Fork&Star，框架和技术实现不妥之处，请帮忙指正），谢谢！

-------------------------------------------

基于MVVM框架的高德天气APP：

功能点实现说明：

左右滑动实现：ViewPager实现左右页面滑动切换；

一、实现方式选型：

ViewPager+PagerAdapter

备注：弃用方案：ViewPager+FragmentPagerAdapter,不适合此场景（View一致，data不同，count动态）

二、代码实现：

1. WtMainActivity.java 相关实现：

private ViewPager mViewPager;
private CityPagerAdapter mCityPagerAdapter;
private PageIndicatorView mPageIndicatorView;

mViewPager = (ViewPager) findViewById(R.id.viewpager);
mCityPagerAdapter = new CityPagerAdapter(this, mViewModel);
mViewPager.setAdapter(mCityPagerAdapter);
mViewModel.registerPageChangeListener(mViewPager);

mPageIndicatorView = findViewById(R.id.page_indicatior);
mPageIndicatorView.registerPageChangeListener(mViewPager);

2. CityPagerAdapter.java Pager页面实现：

public class CityPagerAdapter extends PagerAdapter {
    private Context mContext;
    private List<CityBean> mCityBeans;
    private Map<CityBean, View> mViewDatas = new HashMap<>();
    private LayoutInflater mLayoutInflater;
    private MainActivityViewModel mViewModel;

    public CityPagerAdapter(Context context, MainActivityViewModel viewmodel) {
        this.mContext = context;
        this.mViewModel = viewmodel;
        this.mCityBeans = viewmodel.getCityInfoList();
        mLayoutInflater = LayoutInflater.from(context);
    }

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

    @Override
    public boolean isViewFromObject(@NonNull View view, @NonNull Object object) {
        //return false;
        return view == object;
    }

    @Override
    public View instantiateItem(ViewGroup container, int position) {
        //demo code
        /*TextView textView = new TextView(mContext);
        textView.setText(mCityBeans.get(position).adrName);
        container.addView(textView);
        return textView;*/
        View createdView = getViewItemByCity(mCityBeans.get(position));
        if (createdView == null) {
            View newView = mLayoutInflater.inflate(R.layout.item_city_pager_view, container,false);//无false参数报错
            RecyclerView recyclerView = newView.findViewById(R.id.recycler_view);
            recyclerView.setAdapter(mViewModel.getCityWeatherRecyclerAdapter(mCityBeans.get(position)));
            recyclerView.setLayoutManager(new LinearLayoutManager(mContext));//必须添加此项，否则无法显示
            createdView = newView;
        }

        container.addView(createdView);
        return createdView;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        View view = (View) object;
        container.removeView(view);
    }

    public View getViewItemByCity(CityBean cityinfo) {
        if (mViewDatas == null) {
            return null;
        }
        return mViewDatas.get(cityinfo);
    }
}

3. activity_weather_main.xml 布局文件：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ui.activity.WtMainActivity">

    <com.example.commonui.ActionBar xmlns:actionbar="http://schemas.android.com/apk/res-auto"
        android:id="@+id/action_bar"
        android:layout_width="match_parent"
        android:layout_height="@dimen/actionbar_height"
        android:background="@color/actionbar_background"
        android:gravity="center_vertical"
        actionbar:iv_left_icon="@drawable/ic_action_bar_left"
        actionbar:iv_right_icon="@drawable/ic_action_bar_right"
        actionbar:tv_title_str="深圳" />

    <com.example.commonui.PageIndicatorView
        android:id="@+id/page_indicatior"
        android:layout_width="match_parent"
        android:layout_height="20dp"
        android:layout_below="@+id/action_bar"
        android:layout_centerHorizontal="true">

    </com.example.commonui.PageIndicatorView>

    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_below="@+id/page_indicatior"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    </android.support.v4.view.ViewPager>
</RelativeLayout>

4. item_city_pager_view.xml 单个页面的具体实现：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@+id/action_bar" />
</LinearLayout>

-------------------------------------------

文章目录（未完，待续）：

一：android 应用子功能及移动框架总述 https://blog.csdn.net/cbk861110/article/details/86665564

二：android 高德天气API说明及城市天气查询实现 https://blog.csdn.net/cbk861110/article/details/86665655

三：android 自定义控件实现(ActionBar + PageIndicatorView) https://blog.csdn.net/cbk861110/article/details/86665790

四：android ViewPager实现左右页面滑动切换 https://blog.csdn.net/cbk861110/article/details/86665964

五：android应用权限动态申请 https://blog.csdn.net/cbk861110/article/details/86666321

六：android RecyclerView 封装及使用 https://blog.csdn.net/cbk861110/article/details/86666392

七：android Xutils3文件下载实现（高德天气城市配置） https://blog.csdn.net/cbk861110/article/details/86666573

八：android DiskLruCache 磁盘缓存封装和使用 https://blog.csdn.net/cbk861110/article/details/86666664

九：android ThreadPoolExecutor线程池封装及使用 https://blog.csdn.net/cbk861110/article/details/86667101

十：android 天气网络请求框架(retrofit2&okhttp3&Gson) 封装及使用 https://blog.csdn.net/cbk861110/article/details/86667375

十一：android RxAndroid(响应式编程) 异步网络请求实现 https://blog.csdn.net/cbk861110/article/details/86669178

十二：android DataBinding 数据和UI双向绑定实现 https://blog.csdn.net/cbk861110/article/details/86669708

十三：android room数据库天气数据读写实现 https://blog.csdn.net/cbk861110/article/details/86670354

十四：android LiveData 使用方法（实现城市天气自动刷新） https://blog.csdn.net/cbk861110/article/details/86670531

十五：android ViewModel 使用方法 https://blog.csdn.net/cbk861110/article/details/86670703

十六：android 集成友盟消息推送机制（U-Push） https://blog.csdn.net/cbk861110/article/details/86683849

-------------------------------------------

【版权说明】

1. 请支持原创，转载请注明出处：https://blog.csdn.net/cbk861110/article/details/86665564

2. 项目源码请移步：https://github.com/caobaokang419/WeatherApp（欢迎Github Fork&Star，框架和技术实现不妥之处，请帮忙指正），谢谢！