.Net PDF文件转为Base64字符串

public CommonResult<string> PdfToBase64(string fileUrl)
{
CommonResult<string> result = new CommonResult<string>();
try
{
if (!string.IsNullOrWhiteSpace(fileUrl.Trim()))
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(fileUrl);
request.Method = "GET";
byte[] fileBytes;
using (WebResponse webRes = request.GetResponse())
{
int length = (int)webRes.ContentLength;
HttpWebResponse response = webRes as HttpWebResponse;
Stream stream = response.GetResponseStream();

//读取到内存
MemoryStream stmMemory = new MemoryStream();
byte[] buffer = new byte[length];
int i;
//将字节逐个放入到Byte中
while ((i = stream.Read(buffer, 0, buffer.Length)) > 0)
{
stmMemory.Write(buffer, 0, i);
}
fileBytes = stmMemory.ToArray();//文件流Byte
stmMemory.Close();

string base64 = Convert.ToBase64String(fileBytes);
result.resultData = base64;
result.code = 200;
}
}
else
{
result.code = -1;
result.message = "参数不能为空！";
}
}
catch (Exception ex)
{
Log4NetHelper.Error("远程调用pdf转成base64字符串失败",ex);
result.code = -1;
result.message = ex.Message;
}
return result;
}