Question

我有一个返回流的WCF Web服务。在客户端，当我尝试使用下面的代码读取它然后我在行“Byte [] buffer = new Byte [outputMessage.FileByteStream.Length];”行获得异常说System.Notsupported。请告诉我这里我做错了什么。

        FileMetaData metaData = new FileMetaData();
        metaData.ProductIDsArray = new string[] { "1", "2" };
        metaData.AuthenticationKey = "test";
        FileDownloadMessage inputParam = new FileDownloadMessage(metaData);
        FileTransferServiceClient obj = new FileTransferServiceClient();
        FileDownloadReturnMessage outputMessage = obj.DownloadFile(inputParam);
        Byte[] buffer = new Byte[outputMessage.FileByteStream.Length];
        int byteRead = outputMessage.FileByteStream.Read(buffer, 0, buffer.Length);
        Response.Buffer = false;

        Response.Buffer = false;
        Response.ContentType = "application/x-zip";
        Response.AppendHeader("content-length", buffer.Length.ToString());
        Stream outStream = Response.OutputStream;


        while (byteRead > 0)
        {
            outStream.Write(buffer, 0, buffer.Length);
            byteRead = outputMessage.FileByteStream.Read(buffer, 0, buffer.Length);
        }
        outputMessage.FileByteStream.Close();
        outStream.Close();

Answer 1

您正在读取的流不支持获取流的长度（很可能是因为在下载整个文件之前将无法知道长度）。以块的形式读取流 - 类似于while循环的行为，但是有一个固定大小的缓冲区 - 一旦你为byteRead返回0，你就会知道你已经达到了流末尾。

获取流长度时WCF异常

1 个答案: