C#请求Post接口

1. 应用场景

防止前端直接调用某些隐私接口造成数据泄露，可以采用后端调用接口的方式，这样避免前端传参导致的数据泄露问题。

2. 解决方案

使用类HttpWebRequest，核心代码如下：

/// 

/// 接口请求
/// 
/// 请求地址
/// 
public static string GetToken(string url)
        {
            string result = "";//返回结果
            HttpWebRequest request = null;
            HttpWebResponse response = null;
            Stream reqStream = null;
            try
            {
                request = (HttpWebRequest)WebRequest.Create(url);
                request.Method = "POST";
                request.ReadWriteTimeout = 5000;
                //System.Net.WebProxy wp = new System.Net.WebProxy("127.0.0.1:5555", true);// 调试模式下，用于postman拦截测试参数问题
                //request.Proxy = wp;
                request.ProtocolVersion = HttpVersion.Version10;
                request.KeepAlive = false;
                request.ContentType = "application/x-www-form-urlencoded;charset=utf-8";
                request.ServicePoint.Expect100Continue = false;
                //添加Authorization到HTTP头
                request.Headers.Add("Authorization", "Basic ****************");
                Dictionary parameters = new Dictionary();    //参数列表
				parameters.Add("paraName", "paraValue");
				byte[] data = Encoding.UTF8.GetBytes(BuildQuery(parameters, "utf8"));   //使用utf-8格式组装post参数
                request.ContentLength = data.Length;
                reqStream = request.GetRequestStream();
                reqStream.Write(data, 0, data.Length);
                reqStream.Close();
                //获取服务端返回
                response = (HttpWebResponse)request.GetResponse();
                StreamReader sr = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
                result = sr.ReadToEnd().Trim();
                sr.Close();
            }
            catch (Exception e)
            {
                LogManager.DefaultLogger.Error(e);
            }
            finally
            {
                //关闭连接和流
                if (response != null)
                {
                    response.Close();
                }
                if (request != null)
                {
                    request.Abort();
                }
            }
            return result;
        }


//组装请求参数
private string BuildQuery(IDictionary parameters, string encode)
{
    StringBuilder postData = new StringBuilder();
    bool hasParam = false;
    IEnumerator> dem = parameters.GetEnumerator();
    while (dem.MoveNext())
    {
        string name = dem.Current.Key;
        string value = dem.Current.Value;
        // 忽略参数名或参数值为空的参数
        if (!string.IsNullOrEmpty(name))
        {
            if (hasParam)
            {
                postData.Append("&");
            }
            postData.Append(name);
            postData.Append("=");
            if (encode == "gb2312")
            {
                postData.Append(HttpUtility.UrlEncode(value, Encoding.GetEncoding("gb2312")));
            }
            else if (encode == "utf8")
            {
                postData.Append(HttpUtility.UrlEncode(value, Encoding.UTF8));
            }
            else
            {
                postData.Append(value);
            }
            hasParam = true;
        }
    }
    return postData.ToString();
}

3. 问题汇总

3.1 传参问题

接口请求时总是无法返回正确结果，使用同样的参数在Postman中返回结果正常，通过[设置代理](#3.2 设置代理)进行请求拦截，发现应该时参数传递时出现问题，应该进行encode。参数处理参考如下代码：

Dictionary parameters = new Dictionary();    //参数列表
parameters.Add("paraName", "paraValue");
byte[] data = Encoding.UTF8.GetBytes(BuildQuery(parameters, "utf8"));   //使用utf-8格式组装
request.ContentLength = data.Length;
reqStream = request.GetRequestStream();
reqStream.Write(data, 0, data.Length);
reqStream.Close();
//获取服务端返回
response = (HttpWebResponse)request.GetResponse();


//组装请求参数
private string BuildQuery(IDictionary parameters, string encode)
{
    StringBuilder postData = new StringBuilder();
    bool hasParam = false;
    IEnumerator> dem = parameters.GetEnumerator();
    while (dem.MoveNext())
    {
        string name = dem.Current.Key;
        string value = dem.Current.Value;
        // 忽略参数名或参数值为空的参数
        if (!string.IsNullOrEmpty(name))
        {
            if (hasParam)
            {
                postData.Append("&");
            }
            postData.Append(name);
            postData.Append("=");
            if (encode == "gb2312")
            {
                postData.Append(HttpUtility.UrlEncode(value, Encoding.GetEncoding("gb2312")));
            }
            else if (encode == "utf8")
            {
                postData.Append(HttpUtility.UrlEncode(value, Encoding.UTF8));
            }
            else
            {
                postData.Append(value);
            }
            hasParam = true;
        }
    }
    return postData.ToString();
}

3.2 设置代理

当我们想要查看接口请求的详细内容时，包括请求头与参数等，可以配合Postman设置代理，进行接口请求拦截。共两个步骤：

1. 在代码中添加如下：

   System.Net.WebProxy wp = new System.Net.WebProxy("127.0.0.1:5555", true);// 调试模式下，用于postman拦截测试参数问题
   request.Proxy = wp;
   

   Postman代理端口默认是5555

2. Postman开启代理

   

   注意：调试模式下Postman才可以拦截到请求

   4. 参考链接

   • C# WebRequest设置代理访问
   • C# HttpWebRequest post 请求传参数