Java example source code file (UserAgent.java)

This example Java source code file (UserAgent.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

content\-length, content\-type, exception, got, java, messageheader, net, network, ok\\r\\n, outputstream, server, serversocket, string, thread, url, user-agent, util, www

The UserAgent.java Java example source code

/*
 * Copyright (c) 2001, 2002, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/**
 * @test
 * @bug 4512200
 * @run main/othervm -Dhttp.agent=foo UserAgent
 * @summary  HTTP header "User-Agent" format incorrect
 */

import java.io.*;
import java.util.*;
import java.net.*;
import sun.net.www.MessageHeader;

class Server extends Thread {
    Server (ServerSocket server) {
        this.server = server;
    }
    public void run () {
        try {
            String version = System.getProperty ("java.version");
            String expected = "foo Java/"+version;
            Socket s = server.accept ();
            MessageHeader header = new MessageHeader (s.getInputStream());
            String v = header.findValue ("User-Agent");
            if (!expected.equals (v)) {
                error ("Got unexpected User-Agent: " + v);
            } else {
                success ();
            }
            OutputStream w = s.getOutputStream();
            w.write("HTTP/1.1 200 OK\r\n".getBytes());
            w.write("Content-Type: text/plain\r\n".getBytes());
            w.write("Content-Length: 5\r\n".getBytes());
            w.write("\r\n".getBytes());
            w.write("12345\r\n".getBytes());
        } catch (Exception e) {
            error (e.toString());
        }
    }

    String msg;
    ServerSocket server;
    boolean success;

    synchronized String getMessage () {
        return msg;
    }

    synchronized boolean succeeded () {
        return success;
    }

    synchronized void success () {
        success = true;
    }
    synchronized void error (String s) {
        success = false;
        msg = s;
    }
}

public class UserAgent {

    public static void main(String[] args) throws Exception {
        ServerSocket server = new ServerSocket (0);
        Server s = new Server (server);
        s.start ();
        int port = server.getLocalPort ();
        URL url = new URL ("http://127.0.0.1:"+port);
        URLConnection urlc = url.openConnection ();
        urlc.getInputStream ();
        s.join ();
        if (!s.succeeded()) {
            throw new RuntimeException (s.getMessage());
        }
    }
}