Android——天氣預報（酷歐天氣）（第二篇）

                         **接著上一篇**

功能：傳入請求地址，并注冊一個回呼來處理服務器回應

public class HttpUtil {
    public static void sendOkHttpRequest(String address, okhttp3.Callback callback)
    {
        //OkHttpClient client = new OkHttpClient();
        //傳入請求地址
        Request request = new Request.Builder().url(address).build();
        OkHttpClient client = new OkHttpClient().newBuilder().connectTimeout(60000, TimeUnit.MILLISECONDS)
                .readTimeout(60000, TimeUnit.MILLISECONDS)
                .build();
        //注冊一個回呼來處理服務器回應
        client.newCall(request).enqueue(callback);
    }
}

然后在包內繼續建立一個名為Utility的類
分別用于處理來自服務器的省市縣三級的資料

public class Utility {
    /**
     * 決議和處理服務器回傳的省級資料
     */
    public static boolean handleProvinceResponse(String response)
    {
        if(!TextUtils.isEmpty(response))
        {
            try
            {
                JSONArray allProvinces = new JSONArray(response);
                for (int i = 0; i < allProvinces.length(); i++)
                {
                    JSONObject provinceObject = allProvinces.getJSONObject(i);
                    Province province = new Province();
                    province.setProvinceName(provinceObject.getString("name"));
                    province.setProvinceCode(provinceObject.getInt("id"));
                    //呼叫save()方法將資料存盤到資料庫中
                    province.save();
                }
                return true;
            }catch (JSONException e)
            {
                e.printStackTrace();
            }
        }
        return false;
    }
    /**
     * 決議和處理服務器回傳的市級資料
     */
    public static boolean handleCityResponse(String response, int provinceId)
    {
        if(!TextUtils.isEmpty(response))
        {
            try {
                JSONArray allCities = new JSONArray(response);
                for (int i = 0; i < allCities.length(); i++)
                {
                    JSONObject cityObject = allCities.getJSONObject(i);
                    City city = new City();
                    city.setCityName(cityObject.getString("name"));
                    city.setCityCode(cityObject.getInt("id"));
                    city.setProvinceId(provinceId);
                    //呼叫save()方法將資料存盤到資料庫中
                    city.save();
                }
                return true;
            }catch (JSONException e)
            {
                e.printStackTrace();
            }

        }
        return false;
    }


    /**
     * 決議和處理服務器回傳的縣級資料
     */
    public static boolean handleCountyResponse(String response, int cityId)
    {
        if(!TextUtils.isEmpty(response))
        {
            try {
                JSONArray allCounties = new JSONArray(response);
                for (int i = 0; i < allCounties.length(); i++)
                {
                    JSONObject countyObject = allCounties.getJSONObject(i);
                    County county = new County();
                    county.setCountyName(countyObject.getString("name"));
                    county.setWeatherId(countyObject.getString("weather_id"));
                    county.setCityId(cityId);
                    //呼叫save()方法將資料存盤到資料庫中
                    county.save();
                }
                return true;
            }catch (JSONException e)
            {
                e.printStackTrace();
            }

        }
        return false;
    }

    /**
     * 將回傳的JSON資料決議成Weather物體類
     */
    public static Weather handleWeatherResponse(String response)
    {
        try {
            JSONObject jsonObject = new JSONObject(response);
            JSONArray jsonArray = jsonObject.getJSONArray("HeWeather");
            String weatherContent = jsonArray.getJSONObject(0).toString();
            return new Gson().fromJson(weatherContent,Weather.class);
        }catch (Exception e)
        {
            e.printStackTrace();
        }
        return null;
    }
}

接下來我們建立一個名為choose_area的布局檔案，用于存放標題，回傳鍵，還有省市縣串列
back圖片是我們事先準備好的
代碼如下：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#fff">
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary">
        <TextView
            android:id="@+id/title_text"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:textColor="#fff"
            android:textSize="20sp"/>
        <Button
            android:id="@+id/back_button"
            android:layout_width="25dp"
            android:layout_height="25dp"
            android:layout_marginLeft="10dp"
            android:layout_marginStart="10dp"
            android:layout_alignParentLeft="true"
            android:layout_centerVertical="true"
            android:layout_alignParentStart="true"
            android:background="@drawable/back"/>
    </RelativeLayout>
    <ListView
        android:id="@+id/list_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</LinearLayout>

效果如下：


然后寫一個遍歷省市縣三級的碎片類
名為：ChooseAreaFragment繼承于Fragment
代碼如下：

public class ChooseAreaFragment extends Fragment {
    public static final int LEVEL_PROVINCE = 0;
    public static final int LEVEL_CITY = 1;
    public static final int LEVEL_COUNTY = 2;
    private ProgressDialog progressDialog;
    private TextView titleText;
    private Button backButton;
    private ListView listView;
    private ArrayAdapter<String> adapter;
    private List<String> dataList = new ArrayList<>();

    /**
     * 省串列
     */
    private List<Province> provinceList;

    /**
     * 市串列
     */
    private List<City> cityList;
    /**
     * 縣串列
     */
    private List<County> countyList;
    /**
     * 選中的省份
     */
    private Province selectedProvince;
    /**
     * 選中的城市
     */
    private City selectedCity;
    /**
     * 當前選中的級別
     */
    private int currentLevel;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.choose_area, container, false);
        titleText = (TextView) view.findViewById(R.id.title_text);
        backButton = (Button)view.findViewById(R.id.back_button);
        listView = (ListView) view.findViewById(R.id.list_view);
        adapter = new ArrayAdapter<>(getContext(),android.R.layout.simple_list_item_1, dataList);
        listView.setAdapter(adapter);
        return view;
    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                if(currentLevel == LEVEL_PROVINCE)
                {
                    selectedProvince = provinceList.get(position);
                    queryCities();
                }
                else if (currentLevel == LEVEL_CITY)
                {
                    selectedCity = cityList.get(position);
                    queryCounties();
                }
                else if(currentLevel == LEVEL_COUNTY)
                {
                    String weatherId = countyList.get(position).getWeatherId();

                    if(getActivity() instanceof MainActivity)
                    {
                        Intent intent = new Intent(getActivity(), WeatherActivty.class);
                        intent.putExtra("weather_id",weatherId);
                        startActivity(intent);
                        getActivity().finish();
                    }
                    else if(getActivity() instanceof WeatherActivty)
                    {
                        WeatherActivty activity = (WeatherActivty)getActivity();
                        activity.drawerLayout.closeDrawers();
                        activity.swipeRefresh.setRefreshing(true);
                        activity.requestWeather(weatherId);
                    }


                }

            }
        });
        backButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if(currentLevel == LEVEL_COUNTY)
                {
                    queryCities();
                }
                else if (currentLevel == LEVEL_CITY)
                {
                    queryProvinces();
                }
            }
        });
        queryProvinces();
    }
    private void queryProvinces()
    {
        titleText.setText("中國");
        backButton.setVisibility(View.GONE);
        provinceList = LitePal.findAll(Province.class);
        if(provinceList.size() > 0)
        {
            dataList.clear();
            for (Province province:provinceList)
            {
                dataList.add(province.getProvinceName());
            }
            adapter.notifyDataSetChanged();
            listView.setSelection(0);
            currentLevel = LEVEL_PROVINCE;
        }
        else
        {
            String address = "http://guolin.tech/api/china";
            queryFromServer(address,"province");
        }
    }

    /**
     * 查詢選中省內所有的市，優先從資料庫查詢，如果沒有查詢到再去服務器上查詢
     */
    private void queryCities()
    {
        titleText.setText(selectedProvince.getProvinceName());
        backButton.setVisibility(View.VISIBLE);
        cityList = LitePal.where("provinceid = ?", String.valueOf(selectedProvince.getId())).find(City.class);
        if(cityList.size() > 0)
        {
            dataList.clear();
            for (City city: cityList)
            {
                dataList.add(city.getCityName());
            }
            adapter.notifyDataSetChanged();
            listView.setSelection(0);
            currentLevel = LEVEL_CITY;
        }
        else
        {
            int provinceCode = selectedProvince.getProvinceCode();
            String address = "http://guolin.tech/api/china/" + provinceCode;
            queryFromServer(address,"city");
        }
    }

    /**
     * 查詢選中市內所有的縣，優先從資料庫查詢，如果沒有查詢到再去服務器上查詢
     */
    private void queryCounties()
    {
        titleText.setText(selectedCity.getCityName());
        backButton.setVisibility(View.VISIBLE);
        countyList = LitePal.where("cityid = ?", String.valueOf(selectedCity.getId())).find(County.class);            if(countyList.size() > 0)
    {
        dataList.clear();
        for (County county: countyList)
        {
            dataList.add(county.getCountyName());
        }
        adapter.notifyDataSetChanged();
        listView.setSelection(0);
        currentLevel = LEVEL_COUNTY;
    }
    else
    {
        int provinceCode = selectedProvince.getProvinceCode();
        int cityCode = selectedCity.getCityCode();
        String address = "http://guolin.tech/api/china/" + provinceCode + "/" + cityCode;
        queryFromServer(address,"county");
    }
    }

    /**
     * 根據傳入的地址和型別從服務器上查詢省市縣資料
     */
    private void queryFromServer(String address, final String type)
    {
        showProgressDialog();
        HttpUtil.sendOkHttpRequest(address, new Callback() {
            @Override
            public void onFailure(@NotNull Call call, @NotNull IOException e) {
                //通過runOnUiThread()方法回到主執行緒邏輯
                getActivity().runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        closeProgressDialog();
                        Toast.makeText(getContext(),"加載失敗",Toast.LENGTH_SHORT).show();
                    }
                });
            }

            @Override
            public void onResponse(@NotNull Call call, @NotNull Response response) throws IOException {
                String responseText = response.body().string();
                boolean result = false;
                if("province".equals(type))
                {
                    result = Utility.handleProvinceResponse(responseText);
                }
                else if("city".equals(type))
                {
                    result = Utility.handleCityResponse(responseText,selectedProvince.getId());
                }
                else if("county".equals(type))
                {
                    result = Utility.handleCountyResponse(responseText,selectedCity.getId());
                }
                if (result)
                {
                    getActivity().runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            closeProgressDialog();
                            if("province".equals(type))
                            {
                                queryProvinces();
                            }
                            else if ("city".equals(type))
                            {
                                queryCities();
                            }
                            else if ("county".equals(type))
                            {
                                queryCounties();
                            }
                        }
                    });
                }

            }
        });
    }

    /**
     * 顯示進度對話框
     */
    private void showProgressDialog()
    {
        if(progressDialog == null)
        {
            progressDialog = new ProgressDialog(getActivity());
            progressDialog.setMessage("正在加載···");
            progressDialog.setCanceledOnTouchOutside(false);
        }
        progressDialog.show();
    }

    /**
     * 關閉進度對話框
     */
    private void closeProgressDialog()
    {
        if(progressDialog != null)
        {
            progressDialog.dismiss();
        }
    }
}

然后我們在activity_main.xml顯示碎片
代碼如下：

<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <fragment
        android:id="@+id/choose_area_fragment"
        android:name="com.example.weather2.ChooseAreaFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</FrameLayout>

最后我們在清單檔案中宣告網羅權限

 <uses-permission android:name="android.permission.INTERNET" />

到這里第二篇結束了，我們已經可以查看所有的省市縣三級串列了
效果圖如下：

![在這里插入圖片描述](https://img-blog.csdnimg.cn/20210209201858563.png