c# - Web 服务文件流到字节 [] 到 FileStream 到 pdf 失败 C#

Question

我正在尝试创建一个 web 服务，它以 byte[] 的形式返回一个 pdf 文件，然后使用它的应用程序会抓取byte[] 并将其保存为 pdf 文件，然后打开它。文件最后打不开。

这是返回 byte[]

的 Web 服务

[WebMethod]
public byte[] XXXX(int fileID)
{
    try
    {
        using (EntitiesModel dbContext = new EntitiesModel())
        {   
            string fileFullPath = .....
            .......     
            if (fileFullNamePath != null)
            {
                FileStream fileStream = new FileStream(fileFullNamePath, FileMode.Open, System.IO.FileAccess.Read);
                int len = fileStream.Length.ToInt();
                Byte[] documentContents = new byte[len];
                fileStream.Read(documentContents, 0, len);
                fileStream.Close();
                return documentContents;

然后使用以下代码从应用调用

string soap = "<?xml version=\"1.0\" encoding=\"utf - 8\"?>" +
              "<soap:Envelope xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\">" +
              "<soap:Body>" +
              "<XXXX xmlns=\"http://tempuri.org/\">" +
              "<fileID>XXXXX</fileID>" +
              "</XXXX>" +
              "</soap:Body>" +
              "</soap:Envelope>";
string localhostContext = @"http://localhost:3381/";
string webserviceAddress = @"XXXX/XXXX/XXXXX.asmx";
string url = localhostContext + webserviceAddress ;
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.ContentType = "text/xml";
request.ContentLength = soap.Length;
request.Timeout = 20000;
request.Method = "POST";
using (Stream stream = request.GetRequestStream())
{
    using (StreamWriter streamWriter = new StreamWriter(stream))
    {
        streamWriter.Write(soap);               }
    }
}
byte[] bytes;
try
{
    WebResponse response = request.GetResponse();
    bytes = ReadFully(response.GetResponseStream());
}
catch (Exception exception)
{
    throw;
}

private byte[] ReadFully(Stream input)
{
    byte[] buffer = new byte[16*1024];
    using (MemoryStream memoryStream = new MemoryStream())
    {
        int read;
        while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
        {
            memoryStream.Position = 0;
            memoryStream.Write(buffer, 0, read);
        }
        return memoryStream.ToArray();
    }
}

FileStream objfilestream =
                new FileStream(fileName, FileMode.Create,FileAccess.ReadWrite);
objfilestream.Write(bytes, 0, bytes.Length);
objfilestream.Close();
var process = Process.Start(fileName);

代码运行良好并创建一个 pdf，然后尝试打开该 pdf。但是文件无法打开。 Adobe Acrobat 给出错误

Adobe Acrobat Reader could not open XXX.pdf because it is either not a 
supported file type or because the file has been damaged (for example, it 
was sent as an email attachment and wasn't correctly decoded).

因为我没有在代码中收到错误，所以我不知道错误在哪里，即没有创建正确的文件。

名为input 的Stream 变量没有给出长度，所以我在这里使用了Jon Skeet 的 建议Stackoverflow:Creating a byte array from a stream

new byte[16*1024]; 

而不是

new byte[input.length]

Answer 1

错了三件事。

memoryStream.Position = 0;

在 while 循环中有问题，所以我删除了它。

其次在读取流时。它返回的是 SOAP XMl 消息，在 XXXXResult XML 标记中带有编码的 base64 字符串。所以我必须提取它。

最后我不得不使用

byte[] fileResultBytes  = Convert.FromBase64String(resultString);

从 SOAP 消息中提取的 resultString 中获取 byte[]。在可以在本地生成的测试 SOAP 消息中，它会告诉您此结果字符串的类型。最初我错过了。

感谢VC.One和CodeCaster的正确建议。