修改 Alipay.AopSdk 的HttpWebRequest 为 HttpClient

修改 Alipay.AopSdk 的HttpWebRequest 为 HttpClient，主要是适配Core环境，原因是 HttpWebRequest 在 Core 环境下的连接池管理是没有的，高并发下IIS会崩溃。这里没有用HttpClientFactory 主要因为要加入这个改动量应该是不小的，只能用静态 HttpClient 先代替。

下面代码有待在生产环境验证，做个笔记吧，之前这块高并发中跌了个大跟头

using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Net.Http;
using System.Text;
using System.Web;

namespace Alipay.AopSdk.Core.Util
{
    /// <summary>
    ///     网络工具类。
    /// </summary>
    public sealed class WebUtils
    {
        /// <summary>
        ///     请求与响应的超时时间
        /// </summary>
        public int Timeout { get; set; } = 100000;

        public static HttpClient client = new HttpClient();

        /// <summary>
        ///     执行HTTP POST请求。
        /// </summary>
        /// <param name="url">请求地址</param>
        /// <param name="parameters">请求参数</param>
        /// <param name="charset">编码字符集</param>
        /// <returns>HTTP响应</returns>
        public string DoPost(string url, IDictionary<string, string> parameters, string charset)
        {
            //var req = GetWebRequest(url, "POST");
            //req.ContentType = "application/x-www-form-urlencoded;charset=" + charset;

            var postData = Encoding.GetEncoding(charset).GetBytes(BuildQuery(parameters, charset));
            //var reqStream = req.GetRequestStream();
            //reqStream.Write(postData, 0, postData.Length);
            //reqStream.Close();

            //var rsp = (HttpWebResponse) req.GetResponse();
            //var encoding = Encoding.GetEncoding(rsp.CharacterSet);
            //return GetResponseAsString(rsp, encoding);

            var request = new HttpRequestMessage
            {
                RequestUri = new Uri(url),
                Method = HttpMethod.Post,
                Content = new ByteArrayContent(postData),
            };
            var response = client.SendAsync(request);
            return response.ToString();

        }

        /// <summary>
        ///     执行HTTP GET请求。
        /// </summary>
        /// <param name="url">请求地址</param>
        /// <param name="parameters">请求参数</param>
        /// <param name="charset">编码字符集</param>
        /// <returns>HTTP响应</returns>
        public string DoGet(string url, IDictionary<string, string> parameters, string charset)
        {
            if (parameters != null && parameters.Count > 0)
                if (url.Contains("?"))
                    url = url + "&" + BuildQuery(parameters, charset);
                else
                    url = url + "?" + BuildQuery(parameters, charset);

            //var req = GetWebRequest(url, "GET");
            //req.ContentType = "application/x-www-form-urlencoded;charset=" + charset;

            //var rsp = (HttpWebResponse) req.GetResponse();
            //var encoding = Encoding.GetEncoding(rsp.CharacterSet);
            //return GetResponseAsString(rsp, encoding);

            var request = new HttpRequestMessage
            {
                RequestUri = new Uri(url),
                Method = HttpMethod.Get
            };
            var response = client.SendAsync(request);
            return response.ToString();
        }

        /// <summary>
        ///     执行带文件上传的HTTP POST请求。
        /// </summary>
        /// <param name="url">请求地址</param>
        /// <param name="textParams">请求文本参数</param>
        /// <param name="fileParams">请求文件参数</param>
        /// <param name="charset">编码字符集</param>
        /// <returns>HTTP响应</returns>
        public string DoPost(string url, IDictionary<string, string> textParams, IDictionary<string, FileItem> fileParams,
            string charset)
        {
            // 如果没有文件参数，则走普通POST请求
            if (fileParams == null || fileParams.Count == 0)
                return DoPost(url, textParams, charset);

            var boundary = DateTime.Now.Ticks.ToString("X"); // 随机分隔线

            var req = GetWebRequest(url, "POST");
            req.ContentType = "multipart/form-data;charset=" + charset + ";boundary=" + boundary;

            var reqStream = req.GetRequestStream();
            var itemBoundaryBytes = Encoding.GetEncoding(charset).GetBytes("/r/n--" + boundary + "/r/n");
            var endBoundaryBytes = Encoding.GetEncoding(charset).GetBytes("/r/n--" + boundary + "--/r/n");

            // 组装文本请求参数
            var textTemplate = "Content-Disposition:form-data;name=/"{0}/"/r/nContent-Type:text/plain/r/n/r/n{1}";
            var textEnum = textParams.GetEnumerator();
            while (textEnum.MoveNext())
            {
                var textEntry = string.Format(textTemplate, textEnum.Current.Key, textEnum.Current.Value);
                var itemBytes = Encoding.GetEncoding(charset).GetBytes(textEntry);
                reqStream.Write(itemBoundaryBytes, 0, itemBoundaryBytes.Length);
                reqStream.Write(itemBytes, 0, itemBytes.Length);
            }

            // 组装文件请求参数
            var fileTemplate = "Content-Disposition:form-data;name=/"{0}/";filename=/"{1}/"/r/nContent-Type:{2}/r/n/r/n";
            var fileEnum = fileParams.GetEnumerator();
            while (fileEnum.MoveNext())
            {
                var key = fileEnum.Current.Key;
                var fileItem = fileEnum.Current.Value;
                var fileEntry = string.Format(fileTemplate, key, fileItem.GetFileName(), fileItem.GetMimeType());
                var itemBytes = Encoding.GetEncoding(charset).GetBytes(fileEntry);
                reqStream.Write(itemBoundaryBytes, 0, itemBoundaryBytes.Length);
                reqStream.Write(itemBytes, 0, itemBytes.Length);

                var fileBytes = fileItem.GetContent();
                reqStream.Write(fileBytes, 0, fileBytes.Length);
            }

            reqStream.Write(endBoundaryBytes, 0, endBoundaryBytes.Length);
            reqStream.Close();

            var rsp = (HttpWebResponse)req.GetResponse();
            var encoding = Encoding.GetEncoding(rsp.CharacterSet);
            return GetResponseAsString(rsp, encoding);
        }

        public HttpWebRequest GetWebRequest(string url, string method)
        {
            var req = (HttpWebRequest)WebRequest.Create(url);
            //			req.ServicePoint.Expect100Continue = false;
            req.Method = method;
            req.KeepAlive = true;
            req.UserAgent = "Aop4Net";
            req.Timeout = Timeout;
            return req;
        }

        /// <summary>
        ///     把响应流转换为文本。
        /// </summary>
        /// <param name="rsp">响应流对象</param>
        /// <param name="encoding">编码方式</param>
        /// <returns>响应文本</returns>
        public string GetResponseAsString(HttpWebResponse rsp, Encoding encoding)
        {
            var result = new StringBuilder();
            Stream stream = null;
            StreamReader reader = null;

            try
            {
                // 以字符流的方式读取HTTP响应
                stream = rsp.GetResponseStream();
                reader = new StreamReader(stream, encoding);

                // 按字符读取并写入字符串缓冲
                var ch = -1;
                while ((ch = reader.Read()) > -1)
                {
                    // 过滤结束符
                    var c = (char)ch;
                    if (c != '/0')
                        result.Append(c);
                }
            }
            finally
            {
                // 释放资源
                if (reader != null) reader.Close();
                if (stream != null) stream.Close();
                if (rsp != null) rsp.Close();
            }

            return result.ToString();
        }

        /// <summary>
        ///     组装普通文本请求参数。
        /// </summary>
        /// <param name="parameters">Key-Value形式请求参数字典</param>
        /// <returns>URL编码后的请求数据</returns>
        public static string BuildQuery(IDictionary<string, string> parameters, string charset)
        {
            var postData = new StringBuilder();
            var hasParam = false;

            var dem = parameters.GetEnumerator();
            while (dem.MoveNext())
            {
                var name = dem.Current.Key;
                var value = dem.Current.Value;
                // 忽略参数名或参数值为空的参数
                if (!string.IsNullOrEmpty(name) && !string.IsNullOrEmpty(value))
                {
                    if (hasParam)
                        postData.Append("&");

                    postData.Append(name);
                    postData.Append("=");

                    var encodedValue = HttpUtility.UrlEncode(value, Encoding.GetEncoding(charset));

                    postData.Append(encodedValue);
                    hasParam = true;
                }
            }

            return postData.ToString();
        }
    }
}