browserlauncher.java

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package org.jivesoftware.spark.util;

import java.io.File;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
 * BrowserLauncher is a class that provides one static method, openURL, which opens the default
 * web browser for the current user of the system to the given URL.  It may support other
 * protocols depending on the system -- mailto, ftp, etc. -- but that has not been rigorously
 * tested and is not guaranteed to work.
 * <p/>
 * Yes, this is platform-specific code, and yes, it may rely on classes on certain platforms
 * that are not part of the standard JDK.  What we're trying to do, though, is to take something
 * that's frequently desirable but inherently platform-specific -- opening a default browser --
 * and allow programmers (you, for example) to do so without worrying about dropping into native
 * code or doing anything else similarly evil.
 * <p/>
 * Anyway, this code is completely in Java and will run on all JDK 1.1-compliant systems without
 * modification or a need for additional libraries.  All classes that are required on certain
 * platforms to allow this to run are dynamically loaded at runtime via reflection and, if not
 * found, will not cause this to do anything other than returning an error when opening the
 * browser.
 * <p/>
 * There are certain system requirements for this class, as it's running through Runtime.exec(),
 * which is Java's way of making a native system call.  Currently, this requires that a Macintosh
 * have a Finder which supports the GURL event, which is true for Mac OS 8.0 and 8.1 systems that
 * have the Internet Scripting AppleScript dictionary installed in the Scripting Additions folder
 * in the Extensions folder (which is installed by default as far as I know under Mac OS 8.0 and
 * 8.1), and for all Mac OS 8.5 and later systems.  On Windows, it only runs under Win32 systems
 * (Windows 95, 98, and NT 4.0, as well as later versions of all) that include the
 * FileProtocolHandler method in url.dll, which has been the case for all systems that I have
 * tested.  On other systems, this drops back from the inherently platform-sensitive concept of
 * a default browser and simply attempts to launch Netscape via a shell command.
 * <p/>
 * This code is Copyright 1999 by Eric Albert ([e-mail]) and may be redistributed
 * or modified in any form without restrictions as long as the portion of this comment from this
 * paragraph through the end of the comment is not removed.  The author requests that he be
 * notified of any application, applet, or other binary that makes use of this code, but that's
 * more out of curiosity than anything and is not required.  This software includes no warranty.
 * <p/>
 * Credits:
 * <br>Steven Spencer, JavaWorld magazine (<a href="http://www.javaworld.com/javaworld/javatips/jw-javatip66.html">Java Tip 66</a>)
 * <br>Ron B. Yeh, ZeroG
 * <br>Ben Engber, The New York Times
 *
 * @author Eric Albert (<a href="mailto:[e-mail]">[e-mail]</a>)
 * @author loki der quaeler (modified for osX before adding to weltschmerz frameworks)
 * @version 1.1 (Released July 3, 1999)
 */
public class BrowserLauncher {

    static protected final String OS_X_URL_FILE_NAME = "/tmp/bla_wdml.url";

    /**
     * The Java virtual machine that we are running on.  Actually, in most cases we only care
     * about the operating system, but some operating systems require us to switch on the VM.
     */
    private static int jvm;

    /**
     * The browser for the system
     */
    private static Object browser;

    /**
     * Caches whether any classes, methods, and fields that are not part of the JDK and need to
     * be dynamically loaded at runtime loaded successfully.
     * <p/>
     * Note that if this is <code>false</code>, <code>openURL()</code> will always return an
     * IOException.
     */
    private static boolean loadedWithoutErrors;

    /**
     * The com.apple.mrj.MRJFileUtils class
     */
    private static Class mrjFileUtilsClass;

    /**
     * The com.apple.mrj.MRJOSType class
     */
    private static Class mrjOSTypeClass;

    /**
     * The com.apple.MacOS.MacOSError class
     */
    private static Class macOSErrorClass;

    /**
     * The com.apple.MacOS.AEDesc class
     */
    private static Class aeDescClass;

    /**
     * The <init>(int) method of com.apple.MacOS.AETarget
     */
    private static Constructor aeTargetConstructor;

    /**
     * The <init>(int, int, int) method of com.apple.MacOS.AppleEvent
     */
    private static Constructor appleEventConstructor;

    /**
     * The <init>(String) method of com.apple.MacOS.AEDesc
     */
    private static Constructor aeDescConstructor;

    /**
     * The findFolder method of com.apple.mrj.MRJFileUtils
     */
    private static Method findFolder;

    /**
     * The getFileType method of com.apple.mrj.MRJOSType
     */
    private static Method getFileType;

    /**
     * The makeOSType method of com.apple.MacOS.OSUtils
     */
    private static Method makeOSType;

    /**
     * The putParameter method of com.apple.MacOS.AppleEvent
     */
    private static Method putParameter;

    /**
     * The sendNoReply method of com.apple.MacOS.AppleEvent
     */
    private static Method sendNoReply;

    /**
     * Actually an MRJOSType pointing to the System Folder on a Macintosh
     */
    private static Object kSystemFolderType;

    /**
     * The keyDirectObject AppleEvent parameter type
     */
    private static Integer keyDirectObject;

    /**
     * The kAutoGenerateReturnID AppleEvent code
     */
    private static Integer kAutoGenerateReturnID;

    /**
     * The kAnyTransactionID AppleEvent code
     */
    private static Integer kAnyTransactionID;

    /**
     * JVM constant for MRJ 2.0
     */
    private static final int MRJ_2_0 = 0;

    /**
     * JVM constant for MRJ 2.1 or later
     */
    private static final int MRJ_2_1 = 1;

    /**
     * JVM constant for any Win32 JVM
     */
    private static final int WINDOWS = 2;

    /**
     * even though OS X is a unix variant, would like to differentiate
     */
    static private final int OS_X = 3;

    /**
     * JVM constant for any other platform
     */
    private static final int OTHER = -1;

    /**
     * The file type of the Finder on a Macintosh.  Hardcoding "Finder" would keep non-U.S. English
     * systems from working properly.
     */
    private static final String FINDER_TYPE = "FNDR";

    /**
     * The creator code of the Finder on a Macintosh, which is needed to send AppleEvents to the
     * application.
     */
    private static final String FINDER_CREATOR = "MACS";

    /**
     * The name for the AppleEvent type corresponding to a GetURL event.
     */
    private static final String GURL_EVENT = "GURL";

    /**
     * The first parameter that needs to be passed into Runtime.exec() to open the default web
     * browser on Windows.
     */
    private static final String WINDOWS_PARAMETER = "url.dll,FileProtocolHandler";

    /**
     * The shell parameters for Netscape that opens a given URL in an already-open copy of Netscape
     * on many command-line systems.
     */
    private static final String NETSCAPE_OPEN_PARAMETER_START = " -remote openURL(";
    private static final String NETSCAPE_OPEN_PARAMETER_END = ")";

    /**
     * The message from any exception thrown throughout the initialization process.
     */
    private static String errorMessage;

    /**
     * An initialization block that determines the operating system and loads the necessary
     * runtime data.
     */
    static {
        loadedWithoutErrors = true;
        String osName = System.getProperty("os.name");
        if ("Mac OS".equals(osName)) {
            String mrjVersion = System.getProperty("mrj.version");
            String majorMRJVersion = mrjVersion.substring(0, 3);
            try {
                double version = Double.valueOf(majorMRJVersion).intValue();
                if (version == 2) {
                    jvm = MRJ_2_0;
                }
                else if (version >= 2.1) {
                    // For the time being, assume that all post-2.0 versions of MRJ work the same
                    jvm = MRJ_2_1;
                }
                else {
                    loadedWithoutErrors = false;
                    errorMessage = "Unsupported MRJ version: " + version;
                }
            }
            catch (NumberFormatException nfe) {
                loadedWithoutErrors = false;
                errorMessage = "Invalid MRJ version: " + mrjVersion;
            }
        }
        else if (osName.startsWith("Windows")) {
            jvm = WINDOWS;
        }
        else if (osName.startsWith("Mac OS X")) {
            jvm = OS_X;
        }
        else {
            jvm = OTHER;
        }

        if (loadedWithoutErrors) {    // if we haven't hit any errors yet
            loadedWithoutErrors = loadClasses();
        }
    }

    /**
     * This class should be never be instantiated; this just ensures so.
     */
    private BrowserLauncher() {
    }

    /**
     * Called by a static initializer to load any classes, fields, and methods required at runtime
     * to locate the user's web browser.
     *
     * @return <code>true</code> if all intialization succeeded
     *         <code>false</code> if any portion of the initialization failed
     */
    private static boolean loadClasses() {