RestApiVisitHelper.cs

using Newtonsoft.Json.Linq;
using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
using System.Web;

public class RestApiVisitHelper
{
    // 鉴权 token 的请求头属性名称
    public String TokenHeaderName { get; set; }
    // 默认的鉴权 token 信息
    public String DefaultToken { get; set; }


    public RestApiVisitHelper()
    {

    }

    // 构造时设置鉴权 token 的请求头属性名称
    public RestApiVisitHelper(String tokenHeaderName)
    {
        TokenHeaderName = tokenHeaderName;
    }

    // 构造时设置鉴权 token 的请求头属性名称，以及默认的 token 值
    public RestApiVisitHelper(String tokenHeaderName, String defaultToken){
        TokenHeaderName = tokenHeaderName;
        DefaultToken = defaultToken;
    }  

    public String Get(string apiUrl, Hashtable queryParams)
    {
        return Get(apiUrl, queryParams, DefaultToken);
    }

    private String Get(string apiUrl, Hashtable queryParams, String token)
    {
        System.Net.WebClient webClientObj = CreateWebClient(token);

        apiUrl = FormatUrl(apiUrl, queryParams);
        try
        {
            String result = webClientObj.DownloadString(apiUrl);
            return result;
        } 
        catch (Exception ce)
        {
            return WhenError(ce);
        }
    }

    /// <summary>
    /// Post Api 返回结果文本，使用默认的鉴权 token
    /// </summary>
    /// <param name="apiUrl"></param>
    /// <param name="queryParams"></param>
    /// <param name="body"></param>
    /// <returns></returns>
    public String Post(string apiUrl, Hashtable queryParams, JObject body)
    {
        return Post(apiUrl, queryParams, body, DefaultToken);
    }

    /// <summary>
    /// Post Api 返回结果文本
    /// </summary>
    /// <param name="apiUrl"></param>
    /// <param name="queryParams"></param>
    /// <param name="body"></param>
    /// <param name="token"></param>
    /// <returns></returns>
    public String Post(string apiUrl, Hashtable queryParams, JObject body, String token)
    {
        System.Net.WebClient webClientObj = CreateWebClient(token);

        apiUrl = FormatUrl(apiUrl, queryParams);
        try
        {
            String result = webClientObj.UploadString(apiUrl, "POST", body.ToString(Newtonsoft.Json.Formatting.None));
            return result;
        }
        catch (Exception ce)
        {
            return WhenError(ce);
        }
    }

    public String Put(string apiUrl, Hashtable queryParams, JObject body)
    {
        return Put(apiUrl, queryParams, body, DefaultToken);
    }

    public String Put(string apiUrl, Hashtable queryParams, JObject body, String token)
    {
        System.Net.WebClient webClientObj = CreateWebClient(token);

        apiUrl = FormatUrl(apiUrl, queryParams);
        try
        {
            String result = webClientObj.UploadString(apiUrl, "PUT", body.ToString(Newtonsoft.Json.Formatting.None));
            return result;
        }
        catch (Exception ce)
        {
            return WhenError(ce);
        }
    }

    private String _Delete(string apiUrl, Hashtable queryParams, String token)
    {
        System.Net.WebClient webClientObj = CreateWebClient(token);

        apiUrl = FormatUrl(apiUrl, queryParams);

        try
        {
            String result = webClientObj.UploadString(apiUrl, "DELETE", "");
            return result;
        }
        catch (Exception ce)
        {
            return WhenError(ce);
        }
    }

    #region 私有方法

    // 创建 WebClient 并设置好 token 信息
    private WebClient CreateWebClient(String token)
    {
        System.Net.ServicePointManager.ServerCertificateValidationCallback = ((sender, certificate, chain, sslPolicyErrors) => true);
        System.Net.WebClient webClientObj = new System.Net.WebClient();
        webClientObj.Headers.Add("Accept", "application/json");
        if (!String.IsNullOrEmpty(TokenHeaderName) && !String.IsNullOrEmpty(token))
        {
            webClientObj.Headers.Add(TokenHeaderName, token);
        }
        webClientObj.Encoding = Encoding.UTF8;
        return webClientObj;
    }

    // 将查询参数格式化拼接到 url 上形成最终的访问地址
    private String FormatUrl(String apiUrl, Hashtable queryParams)
    {
        if (queryParams == null) return apiUrl;
        String queryString = "";
        foreach (var k in queryParams.Keys)
        {
            if (!String.IsNullOrEmpty(queryString))
            {
                queryString += "&";
            }
            queryString += String.Format("{0}={1}", k, queryParams[k]);
        }
        if (!String.IsNullOrEmpty(queryString))
        {
            apiUrl += "?" + queryString;
        }
        return apiUrl;
    }

    // 异常时返回的信息：应该根据实际需要进行返回
    private String WhenError(Exception e)
    {
        JObject result = new JObject();
        result["err_code"] = -1;  
        if (e is WebException)
        {
            var we = (WebException)e;
            if (we.Response != null)  // 如果有输出则仍然返回实际输出
            {
                return new StreamReader(we.Response.GetResponseStream()).ReadToEnd();
            }
            else
            {                    
                result["err_msg"] = we.Message;
            }
        }
        else
        { 
            result["err_msg"] = e.Message; 
        }
        return result.ToString(Newtonsoft.Json.Formatting.None);
    }

    #endregion
}