public class SimplePRoxyServer { public static void main(String[] args) throws IOException { try { String host = "your Proxy Server"; int remoteport = 100; int localport = 111; // Print a start-up message System.out.println("Starting proxy for " + host + ":" + remoteport + " on port " + localport); // And start running the server runServer(host, remoteport, localport); // never returns } catch (Exception e) { System.err.println(e); } }
/** * runs a single-threaded proxy server on * the specified local port. It never returns. */ public static void runServer(String host, int remoteport, int localport) throws IOException { // Create a ServerSocket to listen for connections with ServerSocket ss = new ServerSocket(localport);
final byte[] request = new byte[1024]; byte[] reply = new byte[4096];
while (true) { Socket client = null, server = null; try { // Wait for a connection on the local port client = ss.accept();
final InputStream streamFromClient = client.getInputStream(); final OutputStream streamToClient = client.getOutputStream();
// Make a connection to the real server. // If we cannot connect to the server, send an error to the // client, disconnect, and continue waiting for connections. try { server = new Socket(host, remoteport); } catch (IOException e) { PrintWriter out = new PrintWriter(streamToClient); out.print("Proxy server cannot connect to " + host + ":" + remoteport + ":/n" + e + "/n"); out.flush(); client.close(); continue; }
// Get server streams. final InputStream streamFromServer = server.getInputStream(); final OutputStream streamToServer = server.getOutputStream();
// a thread to read the client's requests and pass them // to the server. A separate thread for asynchronous. Thread t = new Thread() { public void run() { int bytesRead; try { while ((bytesRead = streamFromClient.read(request)) != -1) { streamToServer.write(request, 0, bytesRead); streamToServer.flush(); } } catch (IOException e) { }
// the client closed the connection to us, so close our // connection to the server. try { streamToServer.close(); } catch (IOException e) { } } };
// Start the client-to-server request thread running t.start();
// Read the server's responses // and pass them back to the client. int bytesRead; try { while ((bytesRead = streamFromServer.read(reply)) != -1) { streamToClient.write(reply, 0, bytesRead); streamToClient.flush(); } } catch (IOException e) { }
// The server closed its connection to us, so we close our // connection to our client. streamToClient.close(); } catch (IOException e) { System.err.println(e); } finally { try { if (server != null) server.close(); if (client != null) client.close(); } catch (IOException e) { } } } } }
