使用C# 请求Web API及多版本控制（06）

一.C# 请求Web API的方式

（1）前端调用有Form表单提交，ajax提交，ajax一般是用Jquery的简化写法

（2）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。

//先编写几个服务器端的接口方法，便于调用。
        [HttpGet]
        public string CheckLogin(string userName, string pwd)
        {
            if (userName == "admin" && pwd == "123456")
            {
                return "ok";
            }
            else
            {
                return "error";
            }
        }
        [HttpPost]
        public string Register([FromBody]LoginModel model)
        {
            if (model.userName == "admin" && model.pwd == "123456")
            {
                return "ok";
            }
            else
            {
                return "error";
            }
        }
        [HttpPost]
        public string Register2([FromBody]dynamic model)
        {
            if (model.userName == "admin" && model.pwd == "123456")
            {
                return "ok";
            }
            else
            {
                return "error";
            }
        }

1.WebClient

1.Get 请求
WebClient wc = new WebClient();
string url = url1;
wc.Encoding = Encoding.UTF8;
string result = wc.DownloadString(url);
Console.WriteLine(result);
Console.ReadKey();

2. Post的表单提交方式
WebClient wc = new WebClient();
  string url = url3;
  wc.Encoding = Encoding.UTF8;
  //也可以向表头中添加一些其他东西
  wc.Headers.Add("Content-Type", "application/x-www-form-urlencoded");
  string result = wc.UploadString(url, "userName=admin&pwd=123456");
  Console.WriteLine(result);
  Console.ReadKey();

3. Post的JSON提交格式
var user = new
{
  userName = "admin",
  pwd = "123456"
 };
 WebClient wc = new WebClient();
 string url = url3;
 wc.Encoding = Encoding.UTF8;
 wc.Headers.Add("Content-Type", "application/json");
 string result = wc.UploadString(url, jss.Serialize(user));
 Console.WriteLine(result);
 Console.ReadKey();

2.WebRequest

1.Get请求
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url1);
 request.Timeout = 30 * 1000;
 request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.118 Safari/537.36";
 request.ContentType = "application/x-www-form-urlencoded; charset=UTF-8";
 string result = "";
 using (var res = request.GetResponse() as HttpWebResponse)
 {
    if (res.StatusCode == HttpStatusCode.OK)
    {
       StreamReader reader = new StreamReader(res.GetResponseStream(), Encoding.UTF8);
       result = reader.ReadToEnd();
    }
 }
 Console.WriteLine(result);
 Console.ReadKey();

2. Post的表单提交方式
var postData = "userName=admin&pwd=123456";
var request = HttpWebRequest.Create(url2) as HttpWebRequest;
request.Timeout = 30 * 1000;//设置30s的超时
request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.118 Safari/537.36";
request.ContentType = "application/x-www-form-urlencoded";
request.Method = "POST";
byte[] data = Encoding.UTF8.GetBytes(postData);
request.ContentLength = data.Length;
Stream postStream = request.GetRequestStream();
postStream.Write(data, 0, data.Length);
postStream.Close();
string result = "";
using (var res = request.GetResponse() as HttpWebResponse)
{
     if (res.StatusCode == HttpStatusCode.OK)
     {
         StreamReader reader = new StreamReader(res.GetResponseStream(), Encoding.UTF8);
         result = reader.ReadToEnd();
     }
}
Console.WriteLine(result);
Console.ReadKey();

3. Post的JSON提交格式
var user = new
{
     userName = "admin",
     pwd = "123456"
};
var postData = jss.Serialize(user);
var request = HttpWebRequest.Create(url2) as HttpWebRequest;
request.Timeout = 30 * 1000; //设置30s的超时
request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.118 Safari/537.36";
request.ContentType = "application/json";
request.Method = "POST";
byte[] data = Encoding.UTF8.GetBytes(postData);
request.ContentLength = data.Length;
Stream postStream = request.GetRequestStream();
postStream.Write(data, 0, data.Length);
postStream.Close();
string result = "";
using (var res = request.GetResponse() as HttpWebResponse)
{
     if (res.StatusCode == HttpStatusCode.OK)
     {
        StreamReader reader = new StreamReader(res.GetResponseStream(), Encoding.UTF8);
        result = reader.ReadToEnd();
     }
}
Console.WriteLine(result);
Console.ReadKey();

3.HttpClient

适多次操作

1.Get请求
var handler = new HttpClientHandler();
using (var http = new HttpClient(handler))
{
     var response = http.GetAsync(url1).Result;
     //获取Http的状态值
     //Console.WriteLine(response.StatusCode);
     string result = response.Content.ReadAsStringAsync().Result;
     Console.WriteLine(result);
     Console.ReadKey();
}

2. Post的表单提交方式
var handler = new HttpClientHandler();
using (var http = new HttpClient(handler))
{
     var content = new StringContent("userName=admin&pwd=123456", Encoding.UTF8, "application/x-www-form-urlencoded");
     var response = http.PostAsync(url2, content).Result;
     //获取Http的状态值
     //Console.WriteLine(response.StatusCode);
     string result = response.Content.ReadAsStringAsync().Result;
     Console.WriteLine(result);
     Console.ReadKey();
}

3. Post的JSON提交格式
var user = new
{
    userName = "admin",
    pwd = "123456"
};
var handler = new HttpClientHandler();
using (var http = new HttpClient(handler))
{
   var content = new StringContent(jss.Serialize(user), Encoding.UTF8, "application/json");
   var response = http.PostAsync(url3, content).Result;
   //获取Http的状态值
   //Console.WriteLine(response.StatusCode);
   string result = response.Content.ReadAsStringAsync().Result;
   Console.WriteLine(result);
   Console.ReadKey();
}

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。

HttpClient提供了异步支持，可以轻松配合async await 实现异步请求。

工厂类，单例。
/// <summary>
    /// 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
    /// </summary>
    public class HttpClientFactory
    {
        private static HttpClient _httpClient = null;
        /// <summary>
        /// 静态的构造函数：只能有一个，且是无参数的
        /// 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
        /// 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
        /// 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。
        /// </summary>
        static HttpClientFactory()
        {
            _httpClient = new HttpClient(new HttpClientHandler());
            _httpClient.Timeout = new TimeSpan(0, 0, 10);
            _httpClient.DefaultRequestHeaders.Connection.Add("keep-alive");
        }
        /// <summary>
        /// 对外开放接口
        /// </summary>
        /// <returns></returns>
        public static HttpClient GetHttpClient()
        {
            return _httpClient;
        }
    }

对HttpClient的封装
public class HttpClientHelper
    {
        /// <summary>
        /// HttpClient的Get请求
        /// </summary>
        ///<param name="url">请求地址,含拼接数据 </param>
        /// <returns></returns>
        public static string Get(string url)
        {
            var http = HttpClientFactory.GetHttpClient();
            var response1 = http.GetAsync(url).Result;
            return response1.Content.ReadAsStringAsync().Result;
        }
         /// <summary>
        /// HttpClient的Post请求
        /// 表单提交模式[application/x-www-form-urlencoded]
        /// </summary>
        /// <param name="url">请求地址,单纯的地址,没有数据拼接</param>
        /// <param name="data">请求数据,格式为:"userName=admin&pwd=123456"</param>
        /// <returns></returns>
        public static string PostForm(string url, string data)
        {
            var http = HttpClientFactory.GetHttpClient();
            var content = new StringContent(data, Encoding.UTF8, "application/x-www-form-urlencoded");
            var response = http.PostAsync(url, content).Result;
            return response.Content.ReadAsStringAsync().Result;
        }
        #endregion
        /// <summary>
        /// HttpClient的Post请求
        /// Json提交模式[application/json]
        /// </summary>
        /// <param name="url">请求地址,单纯的地址,没有数据拼接</param>
        /// <param name="data">请求数据,格式为(Json)对象、或者类对象 </param>
        /// <returns></returns>
        public static string PostJSON(string url, object data)
        {
            var http = HttpClientFactory.GetHttpClient();
            var content = new StringContent(Newtonsoft.Json.JsonConvert.SerializeObject(data), Encoding.UTF8, "application/json");
            var response = http.PostAsync(url, content).Result;
            return response.Content.ReadAsStringAsync().Result;
        }
        #endregion
    }

二.多版本控制

1.概念：保留旧接口的运行、新功能用新接口。

2.解决方案:

（1）不同的版本使用不同的域名：v1.api.ypf.com、v2.api.ypf.com、v3…… （最佳方案）
（2）在Url，报文头等中带不同的版本信息，用Nginx等做反向代理服务，然后将 http://api.ypf.com/api/v1/User/1和http://api.ypf.com/api/v2/User/1 转到不同的服务器处理。
（3）多个版本的 Controller共处在一个项目中，然后使用 [RoutePrefix] 特性来进行区分，这种方案Controller的名字不能一样，如下：