.Net(C#)后台发送Get和Post请求的几种方法总结

1、通过HttpClient发送Get和Post请求

适用平台：.NET Framework 4.5+, .NET Standard 1.1+, .NET Core 1.0+

其它平台的移植版本可以通过Nuget来安装。(Nuget使用方法：http://www.cjavapy.com/article/21/)

命名空间：using System.Net.Http;

HttpClient推荐使用单一实例共享使用，发关请求的方法推荐使用异步的方式，代码如下，

private static readonly HttpClient client = new HttpClient();
//发送Get请求
var responseString = await client.GetStringAsync("http://www.example.com/recepticle.aspx");
//发送Post请求
var values = new Dictionary
{
   { "thing1", "hello" },
   { "thing2", "world" }
};
var content = new FormUrlEncodedContent(values);
var response = await client.PostAsync("http://www.example.com/recepticle.aspx", content);
var responseString = await response.Content.ReadAsStringAsync();

2、通过第三方类库发送Get和Post请求

1）Flurl.Http(可以通过Nuget来安装)

命名空间：using Flurl.Http;

//发送Get请求
var responseString = await "http://www.example.com/recepticle.aspx"
    .GetStringAsync();
//发送Post请求
var responseString = await "http://www.example.com/recepticle.aspx"
    .PostUrlEncodedAsync(new { thing1 = "hello", thing2 = "world" })
    .ReceiveString();

2）RestSharp(可以通过Nuget来安装)

//发送Get和Post请求
 RestClient client = new RestClient("http://example.com");//指定请求的url
 RestRequest req = new RestRequest("resource/{id}", Method.GET);//指定请求的方式，如果Post则改成Method.POST
request.AddParameter("name", "value"); // 添加参数到 URL querystring
request.AddUrlSegment("id", "123"); // 替换上面指定请求方式中的{id}参数
//req.AddBody(body); /*如发送post请求，则用req.AddBody()指定body内容*/
//发送请求得到请求的内容
//如果有header可以使用下面方法添加
//request.AddHeader("header", "value");
IRestResponse response = client.Execute(request);
//上传一个文件
//request.AddFile("file", path);
var content = response.Content; // 未处理的content是string
//还可以下面几种方式发送请求
//发送请求,反序列化请求结果
IRestResponse response2 = client.Execute(request);
var name = response2.Data.Name;
//发送请求下载一个文件，并保存到path路径
client.DownloadData(request).SaveAs(path);
// 简单发送异步请求
await client.ExecuteAsync(request);
// 发送异常请求并且反序列化结果
var asyncHandle = client.ExecuteAsync(request, response => {
    Console.WriteLine(response.Data.Name);
});
//终止异步的请求
asyncHandle.Abort();

3、比较老一点的方法通过WebRequest发送请求

适用平台：.NET Framework 1.1+, .NET Standard 2.0+, .NET Core 1.0+

命名空间：
using System.Net;
using System.Text; // for class Encoding
using System.IO; // for StreamReader

//发送Get请求
var request = (HttpWebRequest)WebRequest.Create("http://www.example.com/recepticle.aspx");
var response = (HttpWebResponse)request.GetResponse();
var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();
//发送Post请求
var request = (HttpWebRequest)WebRequest.Create("http://www.example.com/recepticle.aspx");
var postData = "thing1=hello";
    postData += "&thing2=world";
var data = Encoding.ASCII.GetBytes(postData);
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
request.ContentLength = data.Length;
using (var stream = request.GetRequestStream())
{
    stream.Write(data, 0, data.Length);
}
var response = (HttpWebResponse)request.GetResponse();
var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();

4、通过WebClient的方式发送请求

适用平台：.NET Framework 1.1+, .NET Standard 2.0+, .NET Core 2.0+

命名空间：
using System.Net;
using System.Collections.Specialized;

using System.Net;
using System.Collections.Specialized;
//发送Get请求
 string url = string.Format("http://localhost:28450/api/values?p1=a&p2=b");
 using (var wc = new WebClient())
{
 Encoding enc = Encoding.GetEncoding("UTF-8");
 Byte[] pageData = wc.DownloadData(url);
 string re = enc.GetString(pageData);
}
//发送Post请求
using (var client = new WebClient())
{
    var values = new NameValueCollection();
    values["thing1"] = "hello";
    values["thing2"] = "world";
    var response = client.UploadValues("http://www.example.com/recepticle.aspx", values);
    var responseString = Encoding.Default.GetString(response);
}