第九十六回网络综合示例：获取天气信息-Toy模板网

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我们在上一章回中介绍了dio库中转换器相关的内容，本章回中将介绍网络综合示例：获取天气信息.闲话休提，让我们一起Talk Flutter吧。

概念介绍

我们在前面章回中介绍了网络操作相关的内容，本章回中将综合利用这些内容实现一个获取天气信息的例子。主要包含dio库的使用、网络操作的封装和JSON数据解析这些内容。在实际项目中这些内容是网络内容中必备的内容，而且它们之间需要相互配合才能完成网络操作。

使用方法

导入dio包，并且对它进行封装，主要是网络请求参数和网络操作的封装；
在天气信息网站注册账号并且获取授权使用API的私钥,我注册的是心知天气；
依据API的操作说明配置与请求相关的参数，比如API的path和请求相关的参数；
依据API返回的内容，创建天气信息model类，为转换JSON数据做准备，可以借助插件完成；
使用Button类Widget,在它的onpress属性中发起获取天气信息的操作，然后通过日志打印出天气信息；

示例代码

///封装DIO网络库
///封装常用的网络参数
class HttpConfig {
  static const String BASE_URL = "https://api.seniverse.com";
  static const int TIME_OUT = 15;

  ///对应天气实况
  // var TIAN_QI_SHI_KUANG = "https://api.seniverse.com/v3/weather/now.json?key=your_api_key&location=beijing&language=zh-Hans&unit=c";
  static const PATH_TIAN_QI_SHI_KUANG = "/v3/weather/now.json";

  ///对应24小时逐小时天气预报
  // var HOUR24 = "https://api.seniverse.com/v3/weather/hourly.json?key=your_api_key&location=beijing&language=zh-Hans&unit=c&start=0&hours=24";
  static const PATH_HOUR24 = "/v3/weather/hourly.json";
  ///对应未来15天逐日天气预报和和昨日天气，不过免费的key只能获取3天的天气预报
  // var FORECAST_DAYS = "https://api.seniverse.com/v3/weather/daily.json?key=your_api_key&location=beijing&language=zh-Hans&unit=c&start=0&days=3";
  static const PATH_FORECAST_DAYS = "/v3/weather/daily.json";
}

class HttpRequest {
  static final baseOptions = BaseOptions(
    baseUrl: HttpConfig.BASE_URL,
    connectTimeout: Duration(seconds: HttpConfig.TIME_OUT),
    sendTimeout: Duration(seconds: HttpConfig.TIME_OUT),
    receiveTimeout: Duration(seconds: HttpConfig.TIME_OUT),
  );

  static final mdio = Dio(baseOptions);
///把网络操作相关的功能封装成独立的方法，网络操作相关的数据通过url和params参数传递
  static Future<T> request<T>(String url,{
        String method='get',
        required Map<String,dynamic> params,
        Interceptor? interceptor,
      }) async {

    final option = Options(method: method);

    ///添加拦截器
    Interceptor _interceptor = InterceptorsWrapper(
      onRequest: (options,handler) {
        return handler.next(options);
        },
      onResponse: (response,handler){
        print('response: ' + response.toString());
        return handler.next(response);
        },
      onError: (error,handler) {
        print('response: ' + error.toString());
        return handler.next(error);
        },
    );
    mdio.interceptors.add(_interceptor);

    ///默认也会抛出异常，这里只用来捕获特定的异常
    try {
      Response response = await mdio.request(
          url, queryParameters: params, options: option);
      return response.data;
    }on DioException catch (e) {
      print(e.toString());
      return Future.error(e);
    }
  }
}

///获取天气信息，网络框架使用httpRequest,请求参数使用map添加
_getWeatherInfo() async {
  var url = HttpConfig.BASE_URL+HttpConfig.PATH_TIAN_QI_SHI_KUANG;
  Map<String,String> queryParams = {};
  queryParams['key'] = PrivateKey.key;
  queryParams['location'] = 'beijing';
  queryParams['language'] = 'zh-Hans';
  queryParams['unit'] = 'c';

  TestRequest _testRequest = TestRequest();
  _testRequest.addRequestParams('key',PrivateKey.key)
      .addRequestParams('location', 'beijing')
      .addRequestParams('language', 'zh-Hans')
      .addRequestParams('unit', 'c');
  HttpRequest.request(url, params: queryParams)
  .then((value){
    debugPrint(XZWeatherBeanEntity.fromJson(value).toString());
    XZWeatherBeanEntity.fromJson(value).results?.forEach((element) {
      print("now: ${element.now}");
    });
  });
}

///获取天气信息，网络框架使用httpRequest,请求参数使用map添加
_getWeatherInfo() async {
  var url = HttpConfig.BASE_URL+HttpConfig.PATH_TIAN_QI_SHI_KUANG;
  Map<String,String> queryParams = {};
  queryParams['key'] = PrivateKey.key;
  queryParams['location'] = 'beijing';
  queryParams['language'] = 'zh-Hans';
  queryParams['unit'] = 'c';

  TestRequest _testRequest = TestRequest();
  _testRequest.addRequestParams('key',PrivateKey.key)
      .addRequestParams('location', 'beijing')
      .addRequestParams('language', 'zh-Hans')
      .addRequestParams('unit', 'c');
  HttpRequest.request(url, params: queryParams)
  .then((value){
    debugPrint(XZWeatherBeanEntity.fromJson(value).toString());
    XZWeatherBeanEntity.fromJson(value).results?.forEach((element) {
      print("now: ${element.now}");
    });
  });
}

ElevatedButton(
  onPressed: () {
    debugPrint('get weather button clicked');
    _getWeatherInfo();
  },
  child: Text('get weather by HttpRequest'),
),