C#中.NET Framework4.5 封装https GET 带Header参数方法及调用

在C#的.NET Framework 4.5中，封装一个HTTP GET请求带Header参数通常会使用`HttpClient`类，这是一个线程安全的HTTP客户端API。以下是一个示例，展示了如何创建一个GET请求并添加自定义Header：

using System;
using System.Net.Http;
using System.Threading.Tasks;

public class HttpClientWrapper
{
    private readonly HttpClient _httpClient;

    public HttpClientWrapper()
    {
        _httpClient = new HttpClient();
        // 设置默认的超时时间和取消操作处理
        _httpClient.Timeout = TimeSpan.FromSeconds(10);
        _httpClient.DefaultRequestHeaders.Add("User-Agent", "YourApp/1.0");
    }

    public async Task<string> GetAsync(string url, Dictionary<string, string> headers)
    {
        if (headers != null)
        {
            foreach (var header in headers)
                _httpClient.DefaultRequestHeaders.TryAddWithoutValidation(header.Key, header.Value);
        }

        HttpResponseMessage response = await _httpClient.GetAsync(url);

        if (!response.IsSuccessStatusCode)
        {
            throw new Exception($"Failed to get data from {url}. Status code: {response.StatusCode}");
        }

        return await response.Content.ReadAsStringAsync();
    }
}

// 调用示例
public static async Task Main()
{
    HttpClientWrapper httpClient = new HttpClientWrapper();

    var headers = new Dictionary<string, string>
    {
        {"Authorization", "Bearer your_token"},
        {"Content-Type", "application/json"}
    };

    string result = await httpClient.GetAsync("https://api.example.com/resource", headers);
    Console.WriteLine(result);
}

在这个例子中，`GetAsync`方法接受URL和包含Header键值对的字典作为参数，然后使用`DefaultRequestHeaders`添加这些Header到请求中。注意替换`"YourApp/1.0"`和`"Bearer your_token"`等实际使用的Header值。