Java HTTP proxy server [closed]

Answer 1

You can't implement it as a servlet, and there is no reason to use any form of HTTP client.

A featureless proxy server is a really simple thing:

1. Accept a connection and start a thread for it.
2. Read the request from the client up to the blank line.
3. Extract the GET or CONNECT command or whatever it is and connect to the named host.
4. If that fails, send back an appropriate HTTP error response, close the socket, and forget about it.

5. Otherwise start two threads to copy bytes, one in each direction. Nothing fancy, just

   while ((count = in.read(buffer)) > 0)
   {
       out.write(buffer, 0, count);
   }
   

6. When one of those sockets reads an EOS, shutdown the other socket for output and exit the thread that got the EOS.
7. If the socket that was the source of the EOS is already shutdown for output, close them both.

Or use Apache SQUID.