The process cannot access the file because it is being used by another process in FILE IO, using WCF service

I am using following code to write in file in, but problem occurred when I try to OPEN the file to do some operations in it.. IT give me error The process cannot access the file because it is being used by another process. I am using WCF to get parameter values and using .net 4.0

            string strTemp = Penn.Common.Shared.GlobalConstants.tempFolder;
            string str = System.Web.Hosting.HostingEnvironment.ApplicationPhysicalPath;
            string format= "MM dd yyyy HH mm ss开发者_如何学运维";
            string filename = "XMLFile" + DateTime.Now.ToString(format) + ".xml";
            StringBuilder strbuilder= new StringBuilder();
            strbuilder.Append(str);
            strbuilder.Append(@"\");
            strbuilder.Append(strTemp);
            strbuilder.Append(@"\");
            strbuilder.Append(filename);
            File.Create(strbuilder.ToString());
            File.Open(strbuilder.ToString(), FileMode.Open, FileAccess.Write, FileShare.Write);
            System.IO.StreamWriter objwriter = new StreamWriter(strbuilder.ToString()); 
            objwriter.Write(xml);
            objwriter.Close();

After File.Create the file is already open.

Try something like

using (StreamWriter sw = File.CreateText(strbuilder.ToString())) 
{
   sw.WriteLine(xml);
}

this also closes your streamwriter automatically.