Java example source code file (CGIHandler.java)

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Java - Java tags/keywords

body, cgiclientexception, cgicommandhandler, cgiserverexception, content\-length, datainputstream, eof, head, ioexception, net, network, post, querystring, rmi, string, title, util

The CGIHandler.java Java example source code

/*
 * Copyright (c) 1996, 2013, 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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.
 */
package sun.rmi.transport.proxy;

import java.io.*;
import java.net.*;
import java.util.Hashtable;

/**
 * CGIClientException is thrown when an error is detected
 * in a client's request.
 */
class CGIClientException extends Exception {
    private static final long serialVersionUID = 8147981687059865216L;

    public CGIClientException(String s) {
        super(s);
    }

    public CGIClientException(String s, Throwable cause) {
        super(s, cause);
    }
}

/**
 * CGIServerException is thrown when an error occurs here on the server.
 */
class CGIServerException extends Exception {

    private static final long serialVersionUID = 6928425456704527017L;

    public CGIServerException(String s) {
        super(s);
    }

    public CGIServerException(String s, Throwable cause) {
        super(s, cause);
    }
}

/**
 * CGICommandHandler is the interface to an object that handles a
 * particular supported command.
 */
interface CGICommandHandler {

    /**
     * Return the string form of the command
     * to be recognized in the query string.
     */
    public String getName();

    /**
     * Execute the command with the given string as parameter.
     */
    public void execute(String param) throws CGIClientException, CGIServerException;
}

/**
 * The CGIHandler class contains methods for executing as a CGI program.
 * The main function interprets the query string as a command of the form
 * "<command>=".
 *
 * This class depends on the CGI 1.0 environment variables being set as
 * properties of the same name in this Java VM.
 *
 * All data and methods of this class are static because they are specific
 * to this particular CGI process.
 */
public final class CGIHandler {

    /* get CGI parameters that we need */
    static int ContentLength;
    static String QueryString;
    static String RequestMethod;
    static String ServerName;
    static int ServerPort;

    static {
        java.security.AccessController.doPrivileged(
            new java.security.PrivilegedAction<Void>() {
            public Void run() {
                ContentLength =
                    Integer.getInteger("CONTENT_LENGTH", 0).intValue();
                QueryString = System.getProperty("QUERY_STRING", "");
                RequestMethod = System.getProperty("REQUEST_METHOD", "");
                ServerName = System.getProperty("SERVER_NAME", "");
                ServerPort = Integer.getInteger("SERVER_PORT", 0).intValue();
                return null;
            }
        });
    }

    /* list of handlers for supported commands */
    private static CGICommandHandler commands[] = {
        new CGIForwardCommand(),
        new CGIGethostnameCommand(),
        new CGIPingCommand(),
        new CGITryHostnameCommand()
    };

    /* construct table mapping command strings to handlers */
    private static Hashtable<String, CGICommandHandler> commandLookup;
    static {
        commandLookup = new Hashtable<>();
        for (int i = 0; i < commands.length; ++ i)
            commandLookup.put(commands[i].getName(), commands[i]);
    }

    /* prevent instantiation of this class */
    private CGIHandler() {}

    /**
     * Execute command given in query string on URL.  The string before
     * the first '=' is interpreted as the command name, and the string
     * after the first '=' is the parameters to the command.
     */
    public static void main(String args[])
    {
        try {
            String command, param;
            int delim = QueryString.indexOf("=");
            if (delim == -1) {
                command = QueryString;
                param = "";
            }
            else {
                command = QueryString.substring(0, delim);
                param = QueryString.substring(delim + 1);
            }
            CGICommandHandler handler =
                commandLookup.get(command);
            if (handler != null)
                try {
                    handler.execute(param);
                } catch (CGIClientException e) {
                    e.printStackTrace();
                    returnClientError(e.getMessage());
                } catch (CGIServerException e) {
                    e.printStackTrace();
                    returnServerError(e.getMessage());
                }
            else
                returnClientError("invalid command.");
        } catch (Exception e) {
            e.printStackTrace();
            returnServerError("internal error: " + e.getMessage());
        }
        System.exit(0);
    }

    /**
     * Return an HTML error message indicating there was error in
     * the client's request.
     */
    private static void returnClientError(String message)
    {
        System.out.println("Status: 400 Bad Request: " + message);
        System.out.println("Content-type: text/html");
        System.out.println("");
        System.out.println("<HTML>" +
                           "<HEAD>