C# 使用RestSharp实现Postman中的各种形式的请求

一、导入命名空间

using RestSharp;
using Newtonsoft.Json;	// 用于JSON序列化/反序列化
using Newtonsoft.Json.Linq;	// 用于构建JSON对象

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二、构建客户端

◆ 创建客户端对象

RestClient client = new RestClient();

◆ 设置当前URL

client.BaseUrl = new Uri("https://www.baidu.com/s");

◆ 设置响应超时

client.Timeout = -1;    // 永不超时

◆ 添加默认Header

client.AddDefaultHeader("HeaderKey", "HeaderValue");

◆ 添加单项Cookie

client.AddDefaultParameter("itemKey", "itemValue", ParameterType.Cookie);

◆ 添加多项Cookie

public void addClientCookies(ref RestClient client, string cookie)
{
    string[] cookie_items = cookie.Split(';');
    foreach (string cookie_item in cookie_items)
    {
        if (cookie_item.Trim().Length == 0) continue;
        string cookie_key = cookie_item.Substring(0, cookie_item.IndexOf('=')).Trim();
        string cookie_value = cookie_item.Substring(cookie_item.IndexOf('=') + 1).Trim();
        if (cookie_value.Contains(",")) cookie_value = $"\"{cookie_value}\"";
        client.AddDefaultParameter(cookie_key, cookie_value, ParameterType.Cookie);
    }
}
// 调用示例
addClientCookies(ref client, "item1=value1;item2=value2")

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三、构建请求

◆ 创建请求对象

RestRequest request = new RestRequest(Method.GET); // Post请求：Method.POST

◆ 添加参数Header

request.AddHeader("HeaderKey", "HeaderValue");

◆ 添加单项Cookie

request.AddParameter("itemName", "itemValue", ParameterType.Cookie);

◆ 添加多项Cookie

public void addRequestCookies(ref RestRequest request, string cookie)
{
    string[] cookie_items = cookie.Split(';');
    foreach (string cookie_item in cookie_items)
    {
        if (cookie_item.Trim().Length == 0) continue;
        string cookie_key = cookie_item.Substring(0, cookie_item.IndexOf('=')).Trim();
        string cookie_value = cookie_item.Substring(cookie_item.IndexOf('=') + 1).Trim();
        if (cookie_value.Contains(",")) cookie_value = $"\"{cookie_value}\"";
        request.AddParameter(cookie_key, cookie_value, ParameterType.Cookie);
    }
}
// 调用示例
addRequestCookies(ref request, "item1=value1;item2=value2")

◆ 添加参数Params

request.AddQueryParameter("ParamKey", "ParamValue");

◆ 添加参数Body

> form-data和x-www-form-urlencoded

request.AddParameter("FormKey", "FormValue");

> JSON数据

// 构建需要提交的JSON数据：{"Name": "zhangsan", "Score": [81, 92, 86]}
JObject post_json = new JObject();
post_json.Add("Name", "zhangsan");
JArray score = new JArray() { 81, 92, 86 };
post_json.Add("Score", score);
// 序列化JSON数据
string post_data = JsonConvert.SerializeObject(post_json);
// 将JSON参数添加至请求中
request.AddParameter("application/json", post_data, ParameterType.RequestBody);

> File上传

request.AddFile("FileKey", @"F:\Demo.txt");	// 添加文件

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四、执行Request请求

◆ JSON结果

IRestResponse response = client.Execute(request); // 执行请求
string res_text = response.Content; // 文本结果
JObject res_json = (JObject)JsonConvert.DeserializeObject(res_text); // JSON结果

◆ File下载

byte[] response = client.DownloadData(request);	// 执行请求
System.IO.File.WriteAllBytes(@"F:\Demo.txt", response);  // 将返回结果保存到文件

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★ 小技巧 ★ ：

• 可以使用Fiddler来对比C# RestSharp发送的请求和Postman发送的请求，来测试添加的参数是否达到了同Postman一样的效果。
• 对于同个平台下的多个请求，可共用一个Client发送请求，减少不必要的重复设置参数。此方式也可用在存在Cookie返回的场景。
• 封装的AddCookies方法对于重复的Cookie键只能保留一个，例如淘宝的部分Cookie中含有两个_tb_token_参数，则需要添加代码去除掉没用的那个。

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淘宝平台Sign算法

using System.Security.Cryptography;
using System.Text.RegularExpressions;
using System.Text;

public string md5(string inStr)
 {
     MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
     byte[] InBytes = Encoding.GetEncoding("utf-8").GetBytes(inStr);
     byte[] OutBytes = md5.ComputeHash(InBytes);
     string OutString = "";
     for (int i = 0; i < OutBytes.Length; i++)
     {
         OutString += OutBytes[i].ToString("x2");
     }
     return OutString;
 }
 public string get_sign(string t, string data, string token)
 {
     string appKey = "12574478"; //淘宝的APPkey
     string pre_sign = string.Format("{0}&{1}&{2}&{3}", token, t, appKey, data);
     return md5(pre_sign);
 }

// 从Cookie中匹配Sign算法中所需的token
string token = Regex.Match(cookie, @"_m_h5_tk=\w+_").Value.Trim('_').Replace("m_h5_tk=", "");
// 获取当前时间戳（Sign算法中所需的t参数）
TimeSpan ts = DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, 0);
string t = (Convert.ToInt64(ts.TotalSeconds * 1000)).ToString();
// JSON data处理（Sign算法中所需的data参数）
JObject post_json = new JObject();
string data = JsonConvert.SerializeObject(post_json);
// 生成Sign
string sign = get_sign(t, data, token);