.Net Standard HttpClient封装Htt请求常用操作整理

一、常用Http操作

1.Get请求，有参数，无参数

2.Post 请求，有参数，无参数

3.文件简单下载

修改NetHelper中Post请求方法Bug：请求编码默认UTF8,字符串内存流读取后这是到开始位置。

        /// <summary>
        /// Post 请求，无参(注：默认使用UTF8编码)
        /// </summary>
        /// <param name="url"></param>
        /// <returns></returns>
        public static async Task<string> PostAsync(string url, string content = "")
        {
            HttpClient client = new HttpClient();
            using (MemoryStream ms = new MemoryStream())
            {
                byte[] bytes = Encoding.UTF8.GetBytes(content);
                ms.Write(bytes, , bytes.Length);
                ms.Seek(, SeekOrigin.Begin);//设置指针读取位置，否则发送无效
                HttpContent hc = new StreamContent(ms);
                HttpResponseMessage resp = await client.PostAsync(url, hc);
                return await resp.Content.ReadAsStringAsync();
            }
        }

以前代码：

    /// <summary>
    /// http协议请求方法封装
    /// </summary>
    public class NetHelper
    {
        #region Get请求
        /// <summary>
        /// get请求,无参
        /// </summary>
        /// <param name="url"></param>
        /// <returns></returns>
        public static async Task<string> GetAsync(string url)
        {
            HttpClient client = new HttpClient();
            HttpResponseMessage resp = await client.GetAsync(url);
            //获取响应状态
            //respMsg.StatusCode==200请求成功
            //获取请求内容
            HttpContent respContent = resp.Content;
            return await respContent.ReadAsStringAsync();
        }
        /// <summary>
        /// Get 请求，指定参数
        /// </summary>
        /// <param name="url"></param>
        /// <param name="dic"></param>
        /// <returns></returns>
        public static async Task<string> GetAsync(string url, Dictionary<string, string> dic)
        {
            //参数处理
            StringBuilder builder = new StringBuilder();
            builder.Append(url);
            if (dic.Count > )
            {
                builder.Append("?");
                int i = ;
                foreach (var item in dic)
                {
                    if (i > )
                        builder.Append("&");
                    builder.AppendFormat("{0}={1}", item.Key, item.Value);
                    i++;
                }
            }
            return await GetAsync(builder.ToString());
        }

        /// <summary>
        /// get 请求 -同步处理
        /// </summary>
        /// <param name="url"></param>
        /// <returns></returns>
        public static string Get(string url)
        {
            Task<string> result = GetAsync(url);
            result.Wait();
            return result.Result;
        }
        /// <summary>
        /// Get请求-同步处理
        /// </summary>
        /// <param name="url">请求地址</param>
        /// <param name="dic">请求参数</param>
        /// <returns></returns>
        public static string Get(string url, Dictionary<string, string> dic)
        {
            //参数处理
            StringBuilder builder = new StringBuilder();
            builder.Append(url);
            if (dic.Count > )
            {
                builder.Append("?");
                int i = ;
                foreach (var item in dic)
                {
                    if (i > )
                        builder.Append("&");
                    builder.AppendFormat("{0}={1}", item.Key, item.Value);
                    i++;
                }
            }
            return Get(builder.ToString());
        }
        #endregion

        #region Post 请求处理
        /// <summary>
        /// Post 请求，无参
        /// </summary>
        /// <param name="url"></param>
        /// <returns></returns>
        public static async Task<string> PostAsync(string url, string content = "")
        {
            HttpClient client = new HttpClient();
            using (MemoryStream ms = new MemoryStream())
            {
                byte[] bytes = Encoding.Unicode.GetBytes(content);
                ms.Write(bytes, , bytes.Length);
                HttpContent hc = new StreamContent(ms);
                HttpResponseMessage resp = await client.PostAsync(url, null);
                return await resp.Content.ReadAsStringAsync();
            }
        }
        /// <summary>
        /// Post 请求，处理参数
        /// </summary>
        /// <param name="url"></param>
        /// <param name="dic"></param>
        /// <returns></returns>
        public static async Task<string> PostAsync(string url, Dictionary<string, string> dic)
        {
            HttpClient client = new HttpClient();
            FormUrlEncodedContent data = new FormUrlEncodedContent(dic);
            var r = await client.PostAsync(url, data);
            return await r.Content.ReadAsStringAsync();
            //client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("text/html"));
            //client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/xhtml+xml"));
            //client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/xml", 0.9));
            //client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("image/webp"));
            //client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("*/*", 0.8));
            //hc.Headers.Add("UserAgent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.57 Safari/537.36");
            //hc.Headers.Add("Timeout", timeOut.ToString());
            //hc.Headers.Add("KeepAlive", "true");
        }

        /// <summary>
        /// Post请求，同步，无参
        /// </summary>
        /// <param name="url"></param>
        /// <param name="content"></param>
        /// <returns></returns>
        public static string Post(string url, string content = "")
        {
            Task<string> str = PostAsync(url, content);
            str.Wait();
            return str.Result;
        }
        /// <summary>
        /// Post 请求，同步，参数处理
        /// </summary>
        /// <param name="url"></param>
        /// <param name="dic"></param>
        /// <returns></returns>
        public static string Post(string url, Dictionary<string, string> dic)
        {
            Task<string> str = PostAsync(url, dic);
            str.Wait();
            return str.Result;
        }
        #endregion

        #region 下载文件处理
        /// <summary>
        /// 下载文件
        /// </summary>
        /// <param name="url">链接地址</param>
        /// <param name="target">存储地址</param>
        /// <returns></returns>
        public static bool DownLoad(string url, string target)
        {
            try
            {
                HttpClient client = new HttpClient();
                var t = client.GetByteArrayAsync(url);
                t.Wait();

                var bytes = t.Result;
                using (FileStream fs = new FileStream(target, FileMode.Create))
                {
                    fs.Write(bytes, , bytes.Length);
                    fs.Close();
                }
                return true;
            }
            catch (Exception ex)
            {
                throw new Exception("下载文件失败，", ex);
            }
        }
        #endregion
    }

更多：

.Net Standard 类库的创建和使用

.Net Standard Http请求实例

.Net Standard简介