利用WebRequest類上傳文件

說明：1.WebRequest類是一個抽象類，因此上傳類實際使用的是其子類

2.打開Fiddler軟件，監視正常網頁的文件上傳，能夠看到http協議的請求和響應信息，簡略說明

（第一行：請求說明

POST http://localhost/UpLoad.aspx HTTP/1.1 （請求類型：post，請求地址: http://localhost/UpLoad.aspx，http協議類型：HTTP/1.1）

第二行至多行：請求頭（一系列的 key:value）

User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:42.0) Gecko/20100101 Firefox/42.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Content-Type: multipart/form-data;charset=utf-8;boundary=8D30475B6E5BB4C
Host:localhost
Content-Length: 22194
Expect: 100-continue
Connection: Close

換行，第n行：請求體

響應相似，詳細見fiddler。

3.經過查看fiddler監測的http請求過程，能夠利用webrequest模擬http請求，代碼以下：

 private void UploadFile(string  path)
    {
        try
        {
            if (!string.IsNullOrEmpty(path))
            {
                string filename = Path.GetFileName(path); //獲取文件名稱
                LogWrite("上傳文件", "開始上傳文件，文件名稱" + filename, null);
                string boundary = DateTime.Now.Ticks.ToString("X"); // 隨機分隔線               
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://localhost/UpLoad.aspx");
                request.ServicePoint.ConnectionLimit = 50; //設置最大鏈接數
                request.ServicePoint.Expect100Continue = false;//解決webexception操做超時

                request.Method = "POST"; //請求方法
                #region ==請求頭===
                request.KeepAlive = false; //請求鏈接方式，設置爲請求完成後斷開鏈接
                request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:42.0) Gecko/20100101 Firefox/42.0";
                request.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8";
                request.ContentType = "multipart/form-data;charset=utf-8;boundary=" + boundary;
                #endregion             
                byte[] itemBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "\r\n");//分割線數據
                byte[] endBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");//結束分割線數據
                StringBuilder sbHeader = new StringBuilder(string.Format("Content-Disposition:form-data;name=\"file\";filename=\"{0}\"\r\nContent-Type:application/octet-stream\r\n\r\n", filename));
                byte[] postHeaderBytes = Encoding.UTF8.GetBytes(sbHeader.ToString()); //上傳文件頭數據
                string sbheader2 = string.Format("Content-Disposition:form-data;name=\"ws\"\r\n\r\nother");//其餘的form表單數據,這裏爲：form["ws"]="other"
                byte[] ddd = Encoding.UTF8.GetBytes(sbheader2);
                FileStream fs = new FileStream(path, FileMode.Open);//讀取文件
                byte[] bArr = new byte[fs.Length];
                long filesize = fs.Length;
                fs.Read(bArr, 0, (int)filesize);
                fs.Close();
                request.ContentLength = itemBoundaryBytes.Length * 2 + ddd.Length + postHeaderBytes.Length + filesize + endBoundaryBytes.Length;//設置請求長度，必定要設置，不然可能會引起請求超時的異常
                Stream sm = request.GetRequestStream(); //獲取請求流
                sm.Write(itemBoundaryBytes, 0, itemBoundaryBytes.Length);//寫入分割線數據
                sm.Write(ddd, 0, ddd.Length); //寫入表單數據
                sm.Write(itemBoundaryBytes, 0, itemBoundaryBytes.Length);//寫入分割線數據
                sm.Write(postHeaderBytes, 0, postHeaderBytes.Length);//寫入上傳文件頭數據

                long size = 0;
                float percent = 0; //上傳進度
                //分步上傳
                while (size < filesize)
                {
                    if (filesize - size > 1024)
                    {
                        sm.Write(bArr, (int)size, 1024); 
                        size += 1024;
                    }
                    else
                    {
                        sm.Write(bArr, (int)size, (int)(filesize - size));
                        size = filesize;
                    }
                    percent = size / (float)filesize;
                }
                //sm.Write(bArr, 0, bArr.Length);


                sm.Write(endBoundaryBytes, 0, endBoundaryBytes.Length); //寫入結束分割線
                sm.Close();
                HttpWebResponse response = (HttpWebResponse)request.GetResponse(); //獲取響應
                Stream sss = response.GetResponseStream();
                LogWrite("上傳文件", response.StatusCode.ToString() + filename, null);

                //Stream sss = request.GetResponse().GetResponseStream();
                StreamReader sr = new StreamReader(sss);
                string ret = sr.ReadToEnd();
                sr.Close();
                LogWrite("上傳文件", "結束上傳文件，返回結果" + ret, null);
                //資源釋放
                response.Close();
                request.Abort();
                System.GC.Collect();
            }
        }
        catch (Exception ex)
        {
            LogWrite("上傳文件發生異常", "", ex);          
        }

    }

4.注意：必定要設置request.ContentLength的大小，不然可能引起操做超時的異常信息。