如何将逐块字节数组转换为base64字符串？

Question

我们正在读取文件的字节数组并将其转换为 base64 字符串，如下所示

    public static string ZipToBase64()
            {
                FileUpload fileCONTENT = FindControl("FileUploadControl") as FileUpload;

                byte[] byteArr = fileCONTENT.FileBytes;

                return Convert.ToBase64String(byteArr);

            }

    string attachmentBytes = ZipToBase64();
    string json1 = "{ \"fileName\": \"Ch01.pdf\", \"data\": " + "\"" + attachmentBytes + "\"}";

当我们尝试将最大 1 GB 的大文件转换为 base64 字符串时，它会抛出内存不足异常。我们正在将此 json 发送到 restful wcf 服务。以下是我在 RESTful WCF 服务中的方法。

 [OperationContract]
        [WebInvoke(Method = "POST", BodyStyle = WebMessageBodyStyle.WrappedRequest, RequestFormat = WebMessageFormat.Json, ResponseFormat = WebMessageFormat.Json)]
        public void UploadFile1(Stream input)
        {

            string UserName = HttpContext.Current.Request.Headers["UserName"];
            string Password = Sql.ToString(HttpContext.Current.Request.Headers["Password"]);
            string sDevideID = Sql.ToString(HttpContext.Current.Request.Headers["DeviceID"]);
            string Version = string.Empty;
            if (validateUser(UserName, Password, Version, sDevideID) == Guid.Empty)
            {
                SplendidError.SystemWarning(new StackTrace(true).GetFrame(0), "Invalid username or password for " + UserName);
                throw (new Exception("Invalid username or password for " + UserName));
            }


            string sRequest = String.Empty;
            using (StreamReader stmRequest = new StreamReader(input, System.Text.Encoding.UTF8))
            {
                sRequest = stmRequest.ReadToEnd();
            }
            // http://weblogs.asp.net/hajan/archive/2010/07/23/javascriptserializer-dictionary-to-json-serialization-and-deserialization.aspx

            JavaScriptSerializer json = new JavaScriptSerializer();
            // 12/12/2014 Paul.  No reason to limit the Json result. 
            json.MaxJsonLength = int.MaxValue;

            Dictionary<string, string> dict = json.Deserialize<Dictionary<string, string>>(sRequest);
            string base64String = dict["data"];
            string fileName = dict["fileName"];


            byte[] fileBytes = Convert.FromBase64String(base64String);
            Stream stream = new MemoryStream(fileBytes);

            //FileStream fs1 = stream as FileStream;

            string networkPath = WebConfigurationManager.AppSettings["NetWorkPath"];
            File.WriteAllBytes(networkPath + "/" + fileName, fileBytes); // Requires System.IO
        }

请提供将大字节数组转换为base64字符串的解决方案

Answer 1

您在 wcf 服务中使用流输入并不真正意味着您以流方式传递任何内容。事实上在你的情况下你没有，因为：

您在内存中缓冲客户端上的整个文件以构建 json 字符串。
您通过 stmRequest.ReadToEnd().

所以没有流式传输发生。首先你应该意识到这里不需要 json - 你只需要在你的 http 请求正文中传递文件。你首先应该做的是在你的 UploadFile1 方法中丢弃所有低于安全检查的代码，而是这样做：

public void UploadFile1(string fileName, Stream input) {
    // check your security headers here
    string networkPath = WebConfigurationManager.AppSettings["NetWorkPath"];
    using (var fs = File.Create(networkPath + "/" + fileName)) {
        input.CopyTo(fs);
    }
}

这里我们只是将输入流复制到输出流（文件），没有任何缓冲（当然CopyTo会缓冲块，但它们会非常小）。用以下标记您的服务方法：

[WebInvoke(Method = "POST", UriTemplate = "/UploadFile1/{fileName}")]

允许您在查询字符串中传递文件名。

现在给客户。不确定您使用哪种方法与服务器通信，我将展示原始 HttpWebRequest 的示例。

var filePath = "path to your zip file here";
var file = new FileInfo(filePath);
// pass file name in query string
var request = (HttpWebRequest)WebRequest.Create("http://YourServiceUrl/UploadFile1/" + file.Name);            
request.Method = "POST";
// set content length
request.ContentLength = file.Length;
// stream file to server
using (var fs = File.OpenRead(file.FullName)) {
    using (var body = request.GetRequestStream()) {
         fs.CopyTo(body);
    }
}
// ensure no errors
request.GetResponse().Dispose();

如何将逐块字节数组转换为base64字符串？

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