Processing an InputStream to OutputStream on the fly through a HttpServlet - servlets

Question

I'm trying to process a large text file through a HttpServlet (tomcat).
As this file can be large and the process should be very fast, I don't want to upload the file on the server and I've used the method HttpRequest.getInputStream to process the input on the fly. For example, I want to transform the input to upper-case with the code below:
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
#SuppressWarnings("serial")
public class EchoServlet extends HttpServlet
{
#Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException
{
OutputStream out=null;
InputStream in=req.getInputStream();
if(in==null) throw new IOException("input is null");
try
{
resp.setContentType("text/plain");
out=resp.getOutputStream();
int c;
while((c=in.read())!=-1)
{
out.write((char)Character.toUpperCase(c));
}
}
catch(IOException err)
{
//ignore
}
finally
{
if(out!=null) out.flush();
if(out!=null) out.close();
in.close();
}
}
}
I invoked my servlet with CURL:
curl -s -d #big.file.txt "http://localhost:8080/test/toupper"
1) processing the input on the fly through a servlet, is it a good/common practice ?
2) my code seems to remove the carriage return ('\n') . Why ?
Thanks

Answer 1

1) processing the input on the fly through a servlet, is it a good/common practice ?
Depends on the functional requirement. I would personally have used a servlet which accepts HTTP multipart/form-data requests instead of raw request bodies. This way it's reuseable on normal HTML forms.
2) my code seems to remove the carriage return ('\n') . Why ?
The given code example doesn't do that. Maybe you've oversimplified it and you was originally using BufferedReader#readLine() while not using PrintWriter#println(). The readLine() indeed eats CRLFs.
There are more issues/inefficiencies in the given code snippet as well, but I can't give a decent answer on that as you seem not to actually be running the code as you posted in the question.