开源项目|易天气

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一款查询中国天气的软件
数据来源：http://apis.baidu.com/apistore/weatherservice

实战中学习Retrofit、RxJava、RxAndroid的实际应用，若未接触过可先移步Retrofit、RxJava&RxAndroid进行学习。

先看效果图：

主界面

开启我们的项目，首先启动Android Studio建立一个工程，在build.gradle添加如下信息：

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compile 'io.reactivex:rxjava:1.1.0'
compile 'io.reactivex:rxandroid:1.1.0'
compile 'com.google.code.gson:gson:2.6.2'
compile 'com.squareup.picasso:picasso:2.5.2'
compile 'com.squareup.retrofit2:retrofit:2.0.0-beta4'
compile 'com.squareup.retrofit2:converter-gson:2.0.0-beta4'
compile 'com.squareup.retrofit2:adapter-rxjava:2.0.0-beta4'
compile 'com.squareup.okhttp3:okhttp:3.4.1'
compile 'com.yalantis:phoenix:1.2.3'

ps:Picasso原本是用不上的，不过还是手贱添加了依赖，后面比较牵强地用上了，实际在此项目中并无明显作用

然后我们来定义一个接口NetService

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public interface NetService {
    @Headers("apikey:a77bae703557e5884b6873af93b603d1")
    @GET("/apistore/weatherservice/recentweathers")
    Observable<Result<Data>> getWeather(@Query("cityname") String cityName, @Query("cityid") String cityId);
    @Headers("apikey:a77bae703557e5884b6873af93b603d1")
    @GET("/apistore/weatherservice/citylist")
    Observable<Result<List<City>>> getCity(@Query("cityname") String cityName);
}

ps:代码中的Observable类是属于RxJava中的，返回的结果集是实体类，具体声明依实际项目需要，此处解析的实体类可参考文末源码中的定义。

接着配置一下Application

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public class BaseApplication extends Application {
    private static Context context;
    private static OkHttpClient client;
    private static Retrofit retrofit;
    private static NetService service;
    private final static long READ_TIME_OUT = 8000;
    private final static String BASEURL = "http://apis.baidu.com";
    @Override
    public void onCreate() {
        super.onCreate();
        context = getApplicationContext();
        initHttpClient();
        initRetrofit();
        initNetService();
    }
    private void initHttpClient() {
        client = new OkHttpClient.Builder()
                .readTimeout(READ_TIME_OUT, TimeUnit.MILLISECONDS)
                .build();
    }
    private void initRetrofit() {
        if (retrofit == null) {
            retrofit = new Retrofit.Builder()
                    .baseUrl(BASEURL)
                    .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
                    .addConverterFactory(GsonConverterFactory.create())
                    .client(client)
                    .build();
        }
    }
    private void initNetService() {
        service = retrofit.create(NetService.class);
    }
    public static Context getContext() {
        return context;
    }
    public static OkHttpClient getHttpClient() {
        return client;
    }
    public static Retrofit getRetrofit() {
        return retrofit;
    }
    public static NetService getService() {
        return service;
    }
}

ps:记得在AndroidManifest.xml文件中配置Application标签，增加android:name属性

开始首页的界面布局就一个ViewPager，每添加一个城市，就往ViewPager里添加一个Fragment。此处使用的PagerAdapter是FragmentStatePagerAdapter，为什么不用FragmentPagerAdapter呢？因为要动态管理城市的天气信息，若使用FragmentPagerAdapter,在删除城市时，页面依然保留在内存中，并没有完全从ViewPager中移除，会造成不好的用户体验，但使用FragmentStatePagerAdapter会造成性能上的损失，在更新城市列表时会有一定的延时，目前还没有好的解决方式，有兴趣的读者可去搜索一下两者的区别。具体代码如下：

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<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/id_weather_page"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
</android.support.v4.view.ViewPager>

ViewPager的Adapter如下：

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public class SimplePagerAdapter extends FragmentStatePagerAdapter {
    private List<Fragment> fragments;
    public SimplePagerAdapter(FragmentManager fm, List<Fragment> fragments) {
        super(fm);
        this.fragments = fragments;
    }
    @Override
    public Fragment getItem(int position) {
        return fragments.get(position);
    }
    @Override
    public int getCount() {
        return fragments.size();
    }
    @Override
    public int getItemPosition(Object object) {
        return PagerAdapter.POSITION_NONE;
    }
}

MainActivity代码如下：

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public class MainActivity extends BaseActivity {
    private ViewPager mWeatherPager;
    private SimplePagerAdapter mAdapter;
    private List<Fragment> mFragments;
    private ArrayList<City> cityList;
    public static MainActivity instance;
    @Override
    protected void initView(Bundle savedInstanceState) {
        setContentView(R.layout.activity_main);
        instance = this;
        mWeatherPager = (ViewPager) findViewById(R.id.id_weather_page);
    }
    @Override
    protected void fetchData() {
        try {
            cityList = (ArrayList<City>) SerializeUtil.getObject(this, "cities");
        } catch (IOException e) {
        } catch (ClassNotFoundException e) {
        } finally {
            if (cityList == null || cityList.size() <= 0) {
                cityList = new ArrayList<>();
                City city = new City();
                city.setProvince_cn(getString(R.string.default_province_cn));
                city.setDistrict_cn(getString(R.string.default_district_cn));
                city.setName_cn(getString(R.string.default_name_cn));
                city.setName_en(getString(R.string.default_name_en));
                city.setArea_id(getString(R.string.default_area_id));
                cityList.add(city);
            }
        }
        mFragments = new ArrayList<>();
        for (City city : cityList) {
            mFragments.add(WeatherFragment.newInstance(city.getName_cn(), city.getArea_id()));
        }
        mAdapter = new SimplePagerAdapter(getSupportFragmentManager(), mFragments);
        mWeatherPager.setAdapter(mAdapter);
        mWeatherPager.setOffscreenPageLimit(mFragments.size() - 1);
    }
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == RESULT_OK) {
            ArrayList<City> cities = (ArrayList<City>) data.getExtras().getSerializable("cities");
            if (cities.size() == 0){  
                City city = new City();
                city.setProvince_cn(getString(R.string.default_province_cn));
                city.setDistrict_cn(getString(R.string.default_district_cn));
                city.setName_cn(getString(R.string.default_name_cn));
                city.setName_en(getString(R.string.default_name_en));
                city.setArea_id(getString(R.string.default_area_id));
                cities.add(city);
	    }
	    cityList.clear();
	    cityList.addAll(cities);
            mFragments.clear();
            for (City city : cityList) {
                mFragments.add(WeatherFragment.newInstance(city.getName_cn(), city.getArea_id()));
            }
            mAdapter.notifyDataSetChanged();
            mWeatherPager.setOffscreenPageLimit(mFragments.size() - 1);
        }
    }
    @Override
    protected void onDestroy() {
        super.onDestroy();
        try {
            SerializeUtil.saveObject(this, cityList, "cities");
        } catch (IOException e) {
        }
    }
    public ArrayList<City> getCityList() {
        return cityList;
    }
}

此处用到序列化操作，把每次获取的数据在退出应用时进行保存，由于城市的ID是唯一的，故保存的文件名为城市名，序列化的具体代码可参考源码。此处启动Activity的方式采用startActivityForResult的方式，具体启动在Fragment里实现，应注意使用的是getActivity().startActivityForResult(requestCode,intent),这样返回的结果将会在Fragment依附的Activity即MainActivity里进行处理。

说了怎么多，重点来了，就是我们的WeatherFragment，对于Fragment,编译器是不推荐我们直接new一个Fragment，而是让我们自己实现newInstance的方法，并在方法里实现setArguments()方法，具体如下：

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public static WeatherFragment newInstance(String cityName, String cityId) {
    WeatherFragment fragment = new WeatherFragment();
    Bundle args = new Bundle();
    args.putString("city_name", cityName);
    args.putString("city_id", cityId);
    fragment.setArguments(args);
    return fragment;
}

然后在onCreate()里获取参数

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@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    cityName = getArguments().getString("city_name");
    cityId = getArguments().getString("city_id");
}

省略View的初始化过程，具体查看源码，看重点的方法fetchData()

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public void fetchData() {
    try {
        Data data = (Data) SerializeUtil.getObject(getActivity(), cityId);
        if (data != null) {
            setData(data);
        }
    } catch (ClassNotFoundException e) {
    } catch (IOException e) {
    }
    if (!ConnUtil.isNetConnected(getActivity())) {
        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                refreshView.setRefreshing(false);
                Snackbar.make(indexLayout, getString(R.string.net_error), Snackbar.LENGTH_LONG)
                        .setAction(getString(R.string.setting), new View.OnClickListener() {
                            @Override
                            public void onClick(View v) {
                                startActivity(new Intent(Settings.ACTION_WIRELESS_SETTINGS));
                            }
                        }).show();
            }
        }, 1000);
        return;
    }
    BaseApplication.getService().getWeather(cityName, cityId)
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .map(new Func1<Result<Data>, Data>() {
                @Override
                public Data call(Result<Data> dataResult) {
                    if (dataResult == null || dataResult.getErrNum() != 0) {
                        return null;
                    }
                    return dataResult.getRetData();
                }
            })
            .subscribe(new Action1<Data>() {
                @Override
                public void call(Data data) {
		    refreshView.setRefreshing(false);
                    if (data == null) {
                        SnackbarUtil.show(indexLayout, getString(R.string.data_error));
                        return;
                    }
                    setData(data);
                    SnackbarUtil.show(indexLayout, getString(R.string.data_success));
                    try {
                        SerializeUtil.saveObject(getActivity(), data, cityId);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            });
}

逻辑比较简单，先是从文件中获取数据展示到界面上，setData()方法是将数据与View绑定，接着判断是否连接网络，若无网络弹出提示并结束，否则从网络获取数据。subscribeOn()和observeOn()分别用于切换线程。

源码地址