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  • (转)总结.Net下后端的几种请求方式(WebClient、WebRequest、HttpClient)

    一. 前言

    　　前端调用有Form表单提交，ajax提交，ajax一般是用Jquery的简化写法，在这里不再过多介绍； 后端调用大约有这些：WebCient、WebRequest、Httpclient、WebapiClient，重点探讨Get和Post请求，Put和Delete请求用较少。

    下面排着介绍Get和Post的基本写法，最后再封装一下，便于调用。

    PS：其中Post请求有两种，分别是： "application/x-www-form-urlencoded"表单提交的方式 和 "application/json" Json格式提交的方式。

    (1). Post的表单提交的格式为："userName=admin&pwd=123456"。

    (2). Post的Json的提交格式为：将实体(类)转换成json字符串。

    下面先编写几个服务器端的接口方法，便于调用。

    复制代码
     1         //Get http://localhost:2131/api/Forth/CheckLogin?userName=admin&pwd=123456
 2         [HttpGet]
 3         public string CheckLogin(string userName, string pwd)
 4         {
 5             if (userName == "admin" && pwd == "123456")
 6             {
 7                 return "ok";
 8             }
 9             else
10             {
11                 return "error";
12             }
13         }
14 
15 
16         //Post http://localhost:2131/api/Forth/Register 
17         [HttpPost]
18         public string Register([FromBody]LoginModel model)
19         {
20             if (model.userName == "admin" && model.pwd == "123456")
21             {
22                 return "ok";
23             }
24             else
25             {
26                 return "error";
27             }
28         }
29 
30         //Post http://localhost:2131/api/Forth/Register2 
31         [HttpPost]
32         public string Register2([FromBody]dynamic model)
33         {
34             if (model.userName == "admin" && model.pwd == "123456")
35             {
36                 return "ok";
37             }
38             else
39             {
40                 return "error";
41             }
42         }
    复制代码

    为了方便下面的测试，给上述三个地址进行命名描述和序列化方法的初始化

    二. WebClient

     1. Get请求

    1 WebClient wc = new WebClient();
2 string url = url1;
3 wc.Encoding = Encoding.UTF8;
4 string result = wc.DownloadString(url);
5 Console.WriteLine(result);
6 Console.ReadKey();

    2. Post的表单提交方式（url2能访问，url3报500错误）

    复制代码
    1   WebClient wc = new WebClient();
2   string url = url3;
3   wc.Encoding = Encoding.UTF8;
4   //也可以向表头中添加一些其他东西
5   wc.Headers.Add("Content-Type", "application/x-www-form-urlencoded");
6   string result = wc.UploadString(url, "userName=admin&pwd=123456");
7   Console.WriteLine(result);
8   Console.ReadKey();
    复制代码

    3. Post的JSON提交格式(url2和url3都能正常访问)

    复制代码
     1  var user = new
 2             {
 3                userName = "admin",
 4                pwd = "123456"
 5             };
 6  WebClient wc = new WebClient();
 7  string url = url3;
 8  wc.Encoding = Encoding.UTF8;
 9  wc.Headers.Add("Content-Type", "application/json");
10  string result = wc.UploadString(url, jss.Serialize(user));
11  Console.WriteLine(result);
12  Console.ReadKey();
    复制代码

    三. WebRequest

    1. Get请求

    复制代码
     1  HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url1);
 2  request.Timeout = 30 * 1000;
 3  request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.118 Safari/537.36";
 4  request.ContentType = "application/x-www-form-urlencoded; charset=UTF-8";
 5  string result = "";
 6  using (var res = request.GetResponse() as HttpWebResponse)
 7  {
 8     if (res.StatusCode == HttpStatusCode.OK)
 9     {
10        StreamReader reader = new StreamReader(res.GetResponseStream(), Encoding.UTF8);
11        result = reader.ReadToEnd();
12     }
13  }
14  Console.WriteLine(result);
15  Console.ReadKey();
    复制代码

    2. Post的表单提交方式（url2能访问，url3报500错误）

    复制代码
     1                 var postData = "userName=admin&pwd=123456";
 2                 var request = HttpWebRequest.Create(url2) as HttpWebRequest;
 3                 request.Timeout = 30 * 1000;//设置30s的超时
 4                 request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.118 Safari/537.36";
 5                 request.ContentType = "application/x-www-form-urlencoded";
 6                 request.Method = "POST";
 7                 byte[] data = Encoding.UTF8.GetBytes(postData);
 8                 request.ContentLength = data.Length;
 9                 Stream postStream = request.GetRequestStream();
10                 postStream.Write(data, 0, data.Length);
11                 postStream.Close();
12                 string result = "";
13                 using (var res = request.GetResponse() as HttpWebResponse)
14                 {
15                     if (res.StatusCode == HttpStatusCode.OK)
16                     {
17                         StreamReader reader = new StreamReader(res.GetResponseStream(), Encoding.UTF8);
18                         result = reader.ReadToEnd();
19                     }
20                 }
21                 Console.WriteLine(result);
22                 Console.ReadKey();
    复制代码

    3. Post的JSON提交格式(url2和url3都能正常访问)

    复制代码
     1                 var user = new
 2                 {
 3                     userName = "admin",
 4                     pwd = "123456"
 5                 };
 6                 var postData = jss.Serialize(user);
 7                 var request = HttpWebRequest.Create(url2) as HttpWebRequest;
 8                 request.Timeout = 30 * 1000; //设置30s的超时
 9                 request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.118 Safari/537.36";
10                 request.ContentType = "application/json";
11                 request.Method = "POST";
12                 byte[] data = Encoding.UTF8.GetBytes(postData);
13                 request.ContentLength = data.Length;
14                 Stream postStream = request.GetRequestStream();
15                 postStream.Write(data, 0, data.Length);
16                 postStream.Close();
17                 string result = "";
18                 using (var res = request.GetResponse() as HttpWebResponse)
19                 {
20                     if (res.StatusCode == HttpStatusCode.OK)
21                     {
22                         StreamReader reader = new StreamReader(res.GetResponseStream(), Encoding.UTF8);
23                         result = reader.ReadToEnd();
24                     }
25                 }
26                 Console.WriteLine(result);
27                 Console.ReadKey();
    复制代码

    四. HttpClient

    1. Get请求

    复制代码
     1  　　　　　　　　var handler = new HttpClientHandler();
 2                 using (var http = new HttpClient(handler))
 3                 {
 4                     var response = http.GetAsync(url1).Result;
 5                     //获取Http的状态值
 6                     //Console.WriteLine(response.StatusCode);
 7                     string result = response.Content.ReadAsStringAsync().Result;
 8                     Console.WriteLine(result);
 9                     Console.ReadKey();
10                 }
    复制代码

    2. Post的表单提交方式（url2能访问，url3报500错误）

    复制代码
     1                 var handler = new HttpClientHandler();
 2                 using (var http = new HttpClient(handler))
 3                 {
 4                     var content = new StringContent("userName=admin&pwd=123456", Encoding.UTF8, "application/x-www-form-urlencoded");
 5                     var response = http.PostAsync(url2, content).Result;
 6                     //获取Http的状态值
 7                     //Console.WriteLine(response.StatusCode);
 8                     string result = response.Content.ReadAsStringAsync().Result;
 9                     Console.WriteLine(result);
10                     Console.ReadKey();
11                 }
    复制代码

    3. Post的JSON提交格式(url2和url3都能正常访问)

    复制代码
     1  　　　　　　　　var user = new
 2                 {
 3                     userName = "admin",
 4                     pwd = "123456"
 5                 };
 6                 var handler = new HttpClientHandler();
 7                 using (var http = new HttpClient(handler))
 8                 {
 9                     var content = new StringContent(jss.Serialize(user), Encoding.UTF8, "application/json");
10                     var response = http.PostAsync(url3, content).Result;
11                     //获取Http的状态值
12                     //Console.WriteLine(response.StatusCode);
13                     string result = response.Content.ReadAsStringAsync().Result;
14                     Console.WriteLine(result);
15                     Console.ReadKey();
16                 }
    复制代码

    注：以上代码均是官方的给出的标准写法，但存在很严重的问题，当请求量大的时候，会存在不能释放的问题，解决方案见下面。

    解决方案：

    　　将HttpClient做成单例的，不用Using，全局只有一个，来解决tcp连接不能释放的问题。

    复制代码
     1     /// <summary>
 2     /// 将HttpClient做成单例的，不用Using，全局只有一个
 3     /// 来解决tcp连接不能释放的问题
 4     /// </summary>
 5     public class HttpClientFactory
 6     {
 7         private static HttpClient _httpClient = null;
 8 
 9         /// <summary>
10         /// 静态的构造函数：只能有一个，且是无参数的
11         /// 由CLR保证，只有在程序第一次使用该类之前被调用，而且只能调用一次
12         /// 说明： keep-alive关键字可以理解为一个长链接，超时时间也可以在上面进行设置，例如10秒的超时时间，当然并发量太大，这个10秒应该会抛弃很多请求
13         /// 发送请求的代码没有了using，即这个httpclient不会被手动dispose，而是由系统控制它，当然你的程序重启时，这也就被回收了。
14         /// </summary>
15         static HttpClientFactory()
16         {
17             _httpClient = new HttpClient(new HttpClientHandler());
18             _httpClient.Timeout = new TimeSpan(0, 0, 10);
19             _httpClient.DefaultRequestHeaders.Connection.Add("keep-alive");
20         }
21 
22         /// <summary>
23         /// 对外开放接口
24         /// </summary>
25         /// <returns></returns>
26         public static HttpClient GetHttpClient()
27         {
28             return _httpClient;
29         }
30     }
    复制代码

    优化后调用进行Get和Post请求，代码如下

    复制代码
     1   　　　　　　　　var http = HttpClientFactory.GetHttpClient();
 2                 //1.Get请求
 3                 var response1 = http.GetAsync(url1).Result;
 4                 var result1 = response1.Content.ReadAsStringAsync().Result;
 5                 Console.WriteLine($"Get请求的返回值为：{result1}");
 6                 //2. Post请求【application/x-www-form-urlencoded】
 7                 var content2 = new StringContent("userName=admin&pwd=123456", Encoding.UTF8, "application/x-www-form-urlencoded");
 8                 var response2 = http.PostAsync(url2, content2).Result;
 9                 string result2 = response2.Content.ReadAsStringAsync().Result;
10                 Console.WriteLine($"Post请求【application/x-www-form-urlencoded】的返回值为：{result2}");
11                 //3. Post请求 【application/json】
12                 var user = new
13                 {
14                     userName = "admin",
15                     pwd = "123456"
16                 };
17                 var content3 = new StringContent(jss.Serialize(user), Encoding.UTF8, "application/json");
18                 var response3 = http.PostAsync(url3, content3).Result;
19                 string result3 = response3.Content.ReadAsStringAsync().Result;
20                 Console.WriteLine($"Post请求【application/json】的返回值为：{result3}");
21                 Console.ReadKey();
    复制代码

    五. 扩展

     　　将WebClient、WebRequest、HttpClient三个类进行封装，其中HttpClient做成单例的，便于我们调用。

     RequestWaysHelp

    封装后的调用：

    复制代码
     1 　　　　　　　　  var user = new
 2                 {
 3                     userName = "admin",
 4                     pwd = "123456"
 5                 };
 6                 // WebClient的相关测试
 7                 {
 8                     Console.WriteLine("1.WebClient的相关测试");
 9                     var result1 = RequestWaysHelp.WcGet(url1);
10                     Console.WriteLine(result1);
11                     var result2 = RequestWaysHelp.WcPost1(url2, "userName=admin&pwd=123456");
12                     Console.WriteLine(result2);
13                     var result3 = RequestWaysHelp.WcPost2(url3, user);
14                     Console.WriteLine(result3);
15                 }
16                 // HttpWebRequest的相关测试
17                 {
18                     Console.WriteLine("2.HttpWebRequest的相关测试");
19                     var result1 = RequestWaysHelp.HwGet(url1);
20                     Console.WriteLine(result1);
21                     var result2 = RequestWaysHelp.HwPost1(url2, "userName=admin&pwd=123456");
22                     Console.WriteLine(result2);
23                     var result3 = RequestWaysHelp.HwPost2(url3, user);
24                     Console.WriteLine(result3);
25                 }
26                 // HttpClient的相关测试
27                 {
28                     Console.WriteLine("3.HttpClient的相关测试");
29                     var result1 = RequestWaysHelp.HcGet(url1);
30                     Console.WriteLine(result1);
31                     var result2 = RequestWaysHelp.HcPost1(url2, "userName=admin&pwd=123456");
32                     Console.WriteLine(result2);
33                     var result3 = RequestWaysHelp.HcPost2(url3, user);
34                     Console.WriteLine(result3);
35                 }
    复制代码
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  • 原文地址：https://www.cnblogs.com/bile/p/15151358.html
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