java code for A command-line interface to a Web server

/**
* Copyright (c) 2002 by Phil Hanna
* All rights reserved.
*
* You may study, use, modify, and distribute this
* software for any purpose provided that this
* copyright notice appears in all copies.
*
* This software is provided without warranty
* either expressed or implied.
*/
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
* Mainline for running the Web client
*/
public class MainWebClient
{
/**
* Reads command line parameters, creates a new
* WebClient object, then invokes it.
*/
public static void main(String[] args)
throws IOException
{
// Default values

String host = "localhost";
int port = 80;

// Use values from command line, if specified

for (int i = 0; i < args.length; i++) {
String arg = args[i];
if (arg.equals("-h") || arg.equals("-help")) {
showUsage();
return;
}
else
if (arg.equals("-host") && ++i < args.length)
host = args[i];
else
if (arg.equals("-port") && ++i < args.length)
port = Integer.parseInt(args[i]);
}

// Create and start the Web client

new WebClient(host, port).run();
}

/**
* Displays the calling syntax
*/
private static void showUsage()
{
String[] text = {
"usage: java com.jspcr.debug.webclient.Main"
+ " [-host ]"
+ " [-port ]",
};
for (int i = 0; i < text.length; i++)
System.out.println(text[i]);
}
}


/**
* Copyright (c) 2002 by Phil Hanna
* All rights reserved.
*
* You may study, use, modify, and distribute this
* software for any purpose provided that this
* copyright notice appears in all copies.
*
* This software is provided without warranty
* either expressed or implied.
*/

/**
* A command-line interface to a Web server
*/
class WebClient
{
// Instance variables

private String host;
private int port;

/**
* Creates a new Web client
* @param host the HTTP server
* @param port the server port number
*/
public WebClient(String host, int port)
{
this.host = host;
this.port = port;
}

/**
* Runs the Web client
* @throws IOException if a socket error occurs
*/
public void run() throws IOException
{
int contentLength = 0;

// Open a socket to the Web host

Socket socket = new Socket(host, port);

// Set up to read input from the user
// and echo it to Web host

BufferedReader in =
new BufferedReader(new InputStreamReader(System.in));

PrintWriter out =
new PrintWriter(socket.getOutputStream(), true);

// The first line is the HTTP request
// e.g., "GET /path HTTP/1.0"

String line = in.readLine();
out.println(line);

// Read and echo any other headers, stopping
// when a blank line is encountered.

while ((line = in.readLine()) != null) {

line = line.trim();
out.println(line);
if (line.equals(""))
break;

// Check for a Content-Length header

Pattern p = Pattern.compile
("^\\s*([^:]+):\\s+(.*\\S)\\s*$");
Matcher m = p.matcher(line);
if (m.matches()) {
String name = m.group(1);
String value = m.group(2);
if (name.equalsIgnoreCase("Content-Length"))
contentLength = Integer.parseInt(value);
}
}

// If a non-zero content length header was used,
// read and echo that many bytes to the Web host.

if (contentLength > 0) {
for (int i = 0; i < contentLength; i++)
out.print((char) in.read());
out.flush();
}

// The server is now working on the request.
// Read its output and dump to stdout

in = new BufferedReader(
new InputStreamReader(socket.getInputStream()));

out = new PrintWriter(System.out);

for (;;) {
line = in.readLine();
if (line == null)
break;
out.println(line);
}

// Close files

in.close();
out.close();
socket.close();
}
}