问题
I was passing a large file in the first arg to SendXMLFile() below but, since it was causing the handheld device to "hang"/"freeze" I temporarily hard-coded a much smaller file (3 KB as opposed to 1121 KB) for testing.
The file does indeed exist (in the same folder as the .exe/.dll), as can be seen by this code:
// test with smaller file:
fileName = "DSD_v6666_3_20140310140737916.xml";
MessageBox.Show("Made it before file.Open");
using (FileStream fileTest = File.Open(fileName, FileMode.CreateNew))
{
fileTest.Write(info, 0, info.Length);
fileTest.Flush();
}
if (!File.Exists(fileName))
{
MessageBox.Show(String.Format("{0} does not seem to exist", fileName));
}
else
{
MessageBox.Show(String.Format("{0} DOES seem to exist", fileName));
}
string justFileName = Path.GetFileNameWithoutExtension(fileName);
String uri = String.Format(@"http://SHANNON2:21609/api/inventory/sendXML/gus/woodrow/{0}", justFileName).Trim();
SendXMLFile(fileName, uri, 500);
Here is the code that is then called, attempting to send the file:
public static string SendXMLFile(string xmlFilepath, string uri, int timeout)
{
// TODO: Remove after testing
String s = String.Format("xmlFilepath == {0}, uri == {1}, timeout == {2}", xmlFilepath, uri, timeout);
MessageBox.Show(s);
// </ TODO: Remove after testing
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
//request.KeepAlive = false; // should this be true? <== commented out as a test, but no diff in behavior
request.ProtocolVersion = HttpVersion.Version10;
request.ContentType = "application/xml";
request.Method = "POST";
StringBuilder sb = new StringBuilder();
// TODO: Remove after testing
MessageBox.Show("Made it to just before the StreamReader using");
using (StreamReader sr = new StreamReader(xmlFilepath))
{
// TODO: Remove after testing
MessageBox.Show("Made it just inside the StreamReader using"); // <= This is the last point reached
String line;
while ((line = sr.ReadLine()) != null)
{
// TODO: Remove after testing
MessageBox.Show(string.Format("line == {0}", line));
sb.Append("\r\n");
}
. . .
When I run this, I see:
"Made it before file.Open"
"DSD_v6666_3_20140310140737916.xml DOES seem to exist"
[The xmlFilepath, uri, and timout vals expected]
"Made it to just before the StreamReader using"
"Made it just inside the StreamReader using"
-- but not the "line == ..." message - it hangs, and I have to warm boot the device to bring it back from electronic limbo.
Is there a potential problem with the StreamReader code, or...???
UPDATE
I don't know whether this is a problem is in the data, or a differences I had to make in the code to get it to work in the Compact Framework. I have very similar code that works from a Winforms app:
public static string SendXMLFile(string xmlFilepath, string uri, int timeout)
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
request.KeepAlive = false;
request.ProtocolVersion = HttpVersion.Version10;
request.ContentType = "application/xml";
request.Method = "POST";
StringBuilder sb = new StringBuilder();
using (StreamReader sr = new StreamReader(xmlFilepath))
{
String line;
while ((line = sr.ReadLine()) != null)
{
sb.AppendLine(line);
}
byte[] postBytes = Encoding.UTF8.GetBytes(sb.ToString());
if (timeout < 0)
{
request.ReadWriteTimeout = timeout;
request.Timeout = timeout;
}
request.ContentLength = postBytes.Length;
try
{
Stream requestStream = request.GetRequestStream();
requestStream.Write(postBytes, 0, postBytes.Length);
requestStream.Close();
//using (var response = (HttpWebResponse)request.GetResponse())
//{
// return response.ToString();
//}
// alternate way, safe for older versions of .NET
HttpWebResponse response = null;
try
{
response = (HttpWebResponse)request.GetResponse();
}
finally
{
IDisposable disposableResponse = response as IDisposable;
if (disposableResponse != null) disposableResponse.Dispose();
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
request.Abort();
return string.Empty;
}
}
}
---called like so, passing the same file as a test case:
private void button20_Click(object sender, EventArgs e)
{
// Change the file name before each test
String fullFilePath = @"C:\HoldingTank\DSD_v6666_3_20140310140737916.xml";
string justFileName = Path.GetFileNameWithoutExtension(fullFilePath);
String uri = String.Format(@"http://localhost:21608/api/inventory/sendXML/su/su/{0}", justFileName);
SendXMLFile(fullFilePath, uri, 500);
}
UPDATE 2
I changed the code to use an XMLTextReader, and now I'm back to the err I was previously having, namely "(400) Bad Request" which is documented in most of its gory detail here.
Here is the new code, and what I now see:
public static bool WriteIt2( string fileName, string data, long fsize ) { bool retVal = false; int bytRd = 0; // if use this, change its name string the_Msg = "";
if (File.Exists(fileName))
{
File.Delete(fileName);
}
Byte[] info = Encoding.UTF8.GetBytes(data);
// Testing with this relatively small file for now
fileName = "DSD_v6666_3_20140310140737916.xml";
MessageBox.Show("Made it before file.Open");
using (FileStream fileTest = File.Open(fileName, FileMode.CreateNew))
{
fileTest.Write(info, 0, info.Length);
fileTest.Flush();
}
if (!File.Exists(fileName))
{
MessageBox.Show(String.Format("{0} does not seem to exist", fileName));
} // I have never seen the msg above, but always saw the one below, so commented it out
else //<= always exists, so unnecessary
{
MessageBox.Show(String.Format("{0} DOES seem to exist", fileName));
}
string justFileName = Path.GetFileNameWithoutExtension(fileName);
String uri = String.Format(@"http://SHANNON2:21609/api/inventory/sendXML/su/su/{0}", justFileName).Trim();
SendXMLFile(fileName, uri, 500);
Now here's the code that actually does the reading, writing, and sending (or tries to):
public static string SendXMLFile(string xmlFilepath, string uri, int timeout)
{
String s = String.Format("xmlFilepath == {0}, uri == {1}, timeout == {2}", xmlFilepath, uri, timeout);
MessageBox.Show(s);
// </ TODO: Remove after testing
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
request.ProtocolVersion = HttpVersion.Version10;
request.ContentType = "application/xml";
request.Method = "POST";
StringBuilder sb = new StringBuilder();
MessageBox.Show("Made it to just before the StreamReader using");
StreamReader sr = new StreamReader(xmlFilepath);
MessageBox.Show("Made it past the StreamReader being constructed");
XmlTextReader reader = null;
reader = new XmlTextReader(sr);
while (reader.Read())
{
switch (reader.NodeType)
{
case XmlNodeType.Element: // The node is an Element.
sb.Append("<" + reader.Name);
while (reader.MoveToNextAttribute()) // Read attributes.
sb.Append(" " + reader.Name + "='" + reader.Value + "'");
sb.Append(">");
sb.Append(">");
break;
case XmlNodeType.Text: //Display the text in each element.
sb.Append (reader.Value);
break;
case XmlNodeType. EndElement: //Display end of element.
sb.Append("</" + reader.Name);
sb.Append(">");
break;
}
}
// TODO: Remove after testing
MessageBox.Show("Made it past the while loop");
MessageBox.Show(String.Format("sb first line is {0}", sb[0].ToString()));
MessageBox.Show(String.Format("sb tenth line is {0}", sb[9].ToString()));
byte[] postBytes = Encoding.UTF8.GetBytes(sb.ToString());
if (timeout < 0)
{
request.Timeout = timeout;
}
request.ContentLength = postBytes.Length;
try
{
Stream requestStream = request.GetRequestStream();
requestStream.Write(postBytes, 0, postBytes.Length);
requestStream.Close();
// This code for older versions of .NET from ctacke:
HttpWebResponse response = null;
try
{
response = (HttpWebResponse)request.GetResponse();
return response.ToString();
}
finally
{
IDisposable disposableResponse = response as IDisposable;
if (disposableResponse != null) disposableResponse.Dispose();
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
request.Abort();
return string.Empty;
}
}
What I see now when this runs:
0) "Made it before file.Open"
1) "DSD_v6666_3_20140310140737916.xml DOES seem to exist"
2) [ the xmlFilePath and other args - they are what is expected ]
3) "Made it to just before the StreamReader using"
4) "Made it past the StreamReader being constructed
5) "Made it past the while loop
6) "sb first line is "<"
7) "sb tenth line is ">"
8) "The remote server returned an error (400) Bad Request"
So at least it's no longer hanging, but I'm back to wondering why the server considers this a bad request.
回答1:
I think you should return to basics:
public static string SendXMLFile(string xmlFilepath, string uri, int timeout)
{
using (var client = new WebClient())
{
client.Headers.Add("Content-Type", "application/xml");
byte[] response = client.UploadFile(uri, "POST", xmlFilepath);
return Encoding.ASCII.GetString(response);
}
}
and see what works and what the server thinks of your file.
When you really need a TimeOut then see this answer
来源：https://stackoverflow.com/questions/25557930/why-does-this-code-hang-on-reaching-the-first-readline-from-a-streamreader