使用 HttpClient 调用 Wea​​therAPI

Question

我创建了 Web API 来从 OpenWeatherAPI 接收每日温度。 我把API调用放在MVC项目中； （计划稍后创建新项目以获得更好的微服务架构。）

有人在代码中提到：

在您的 HomeController 中，您试图简单地调用操作，就像在 WeatherController 实例上的方法一样。您还需要在那里使用 HttpClient 。另外，不要直接新建 HttpClient。它应该被视为单例

我将如何执行此操作？这是原始代码，一个月前开始编程。

MVC 页面：

namespace WeatherPage.Controllers
{
    public class HomeController : Controller
    {

        public WeatherController weathercontroller = new WeatherController();

        public IActionResult Index()
        {
            return View();
        }

        public Async Task<IActionResult> About()
        {
            ViewData["Message"] = "Your application description page.";
            ViewData["test"] =  weathercontroller.City("Seattle");
            return View();
        }
    }
}

API 控制器：

[Route("api/[controller]")] 
public class WeatherController : ControllerBase
{
    [HttpGet("[action]/{city}")]
    public async Task<IActionResult> City(string city)
    {
        Rootobject rawWeather = new Rootobject();
        using (var client = new HttpClient())
        {
            try
            {
                client.BaseAddress = new Uri("http://api.openweathermap.org");
                var response = await client.GetAsync($"/data/2.5/weather?q={city}&appid=APIkey&units=metric");
                response.EnsureSuccessStatusCode();

                var stringResult = await response.Content.ReadAsStringAsync();
                rawWeather = JsonConvert.DeserializeObject<Rootobject>(stringResult);
                return Ok(rawWeather);
            }
            catch (HttpRequestException httpRequestException)
            {
                return BadRequest($"Error getting weather from OpenWeather: {httpRequestException.Message}");
            }
        }
    }
}   

public class Rootobject
{
    public Coord coord { get; set; }
    public Weather[] weather { get; set; }
    public string _base { get; set; }
    public Main main { get; set; }
    public int visibility { get; set; }
    public Wind wind { get; set; }
    public Clouds clouds { get; set; }
    public int dt { get; set; }
    public Sys sys { get; set; }
    public int id { get; set; }
    public string name { get; set; }
    public int cod { get; set; }
}

这适用于我的项目： https://localhost:55555/api/weather/city/washington

Retrieve Data From Third party Openweather Api

Should We Call Web Api from Mvc Application in Same Solution

Answer 1

这大致意味着你应该使用依赖注入。

1. 不要在每次需要的时候都创建HttpClient的实例，而是请求HttpClient的实例。
2. 将天气控制器中获取天气的代码提取到服务中，并在天气控制器 api 和家庭控制器中请求该服务

WeatherService：

public interface IWeatherService
{
    Task<Rootobject> CityAsync(string city);
}

public class WeatherService : IWeatherService{
    private HttpClient _httpClient ;
    public WeatherService(IHttpClientFactory clientFactory){
        this._httpClient = clientFactory.CreateClient();
    }


    public async Task<Rootobject> CityAsync(string city){
        Rootobject rawWeather = new Rootobject();
        this._httpClient.BaseAddress = new Uri("http://api.openweathermap.org");
        var response = await this._httpClient.GetAsync($"/data/2.5/weather?q={city}&appid=APIkey&units=metric");
        response.EnsureSuccessStatusCode();

        var stringResult = await response.Content.ReadAsStringAsync();
        return JsonConvert.DeserializeObject<Rootobject>(stringResult);
    }

}

新的 WeatherController ：

[Route("api/[controller]")] 
public class WeatherController : ControllerBase
{
    private IWeatherService _weatherService;

    public WeatherController(IWeatherService wetherService ){
        this._weatherService= wetherService;
    }

    [HttpGet("[action]/{city}")]
    public async Task<IActionResult> City(string city)
    {
        try
        {
            var rawWeather=await this._weatherService.CityAsync(city);
            return Ok(rawWeather);
        }
        catch (HttpRequestException httpRequestException)
        {
            return BadRequest($"Error getting weather from OpenWeather: {httpRequestException.Message}");
        }
    }
}

新的 HomeController：

public class HomeController : Controller
{
    private IWeatherService _weatherService;
    public HomeController(IWeatherService wetherService ){
        this._weatherService= wetherService;
    }

    public IActionResult Index()
    {
        return View();
    }

    public async Task<IActionResult> About()
    {
        ViewData["Message"] = "Your application description page.";
        ViewData["test"] =  await this._weatherService.CityAsync("Seattle");

        return View();
    }

}

配置服务：

services.AddHttpClient();
services.AddSingleton<IWeatherService ,WeatherService>();