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BrowserLauncher.java

package net.sf.ext;

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).  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 1999-2001 by Eric Albert (ejalbert@cs.stanford.edu) 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.  The author is not repsonsible for any loss of data or functionality
 * or any adverse or unexpected effects of using this software.
 * <p>
 * Credits:
 * <br>Steven Spencer, JavaWorld magazine (<a href="http://www.javaworld.com/javaworld/javatips/jw-javatip66.html">Java Tip 66</a>)
 * <br>Thanks also to Ron B. Yeh, Eric Shapiro, Ben Engber, Paul Teitlebaum, Andrea Cantatore,
 * Larry Barowski, Trevor Bedzek, Frank Miedrich, and Ron Rabakukk
 *
 * @author Eric Albert (<a href="mailto:ejalbert@cs.stanford.edu">ejalbert@cs.stanford.edu</a>)
 * @version 1.4b1 (Released June 20, 2001)
 */
00054 public class BrowserLauncher {

    /**
     * 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. */
00059     private static int jvm;

    /** The browser for the system */
00062     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.
     */
00071     private static boolean loadedWithoutErrors;

    /** The com.apple.mrj.MRJFileUtils class */
00074     private static Class<?> mrjFileUtilsClass;

    /** The com.apple.mrj.MRJOSType class */
00077     private static Class<?> mrjOSTypeClass;

    /** The com.apple.MacOS.AEDesc class */
00080     private static Class<?> aeDescClass;
    
    /** The <init>(int) method of com.apple.MacOS.AETarget */
00083     private static Constructor<?> aeTargetConstructor;
    
    /** The <init>(int, int, int) method of com.apple.MacOS.AppleEvent */
00086     private static Constructor<?> appleEventConstructor;
    
    /** The <init>(String) method of com.apple.MacOS.AEDesc */
00089     private static Constructor<?> aeDescConstructor;
    
    /** The findFolder method of com.apple.mrj.MRJFileUtils */
00092     private static Method findFolder;

    /** The getFileCreator method of com.apple.mrj.MRJFileUtils */
00095     private static Method getFileCreator;
    
    /** The getFileType method of com.apple.mrj.MRJFileUtils */
00098     private static Method getFileType;
    
    /** The openURL method of com.apple.mrj.MRJFileUtils */
00101     private static Method openURL;
    
    /** The makeOSType method of com.apple.MacOS.OSUtils */
00104     private static Method makeOSType;
    
    /** The putParameter method of com.apple.MacOS.AppleEvent */
00107     private static Method putParameter;
    
    /** The sendNoReply method of com.apple.MacOS.AppleEvent */
00110     private static Method sendNoReply;
    
    /** Actually an MRJOSType pointing to the System Folder on a Macintosh */
00113     private static Object kSystemFolderType;

    /** The keyDirectObject AppleEvent parameter type */
00116     private static Integer keyDirectObject;

    /** The kAutoGenerateReturnID AppleEvent code */
00119     private static Integer kAutoGenerateReturnID;
    
    /** The kAnyTransactionID AppleEvent code */
00122     private static Integer kAnyTransactionID;

    /** The linkage object required for JDirect 3 on Mac OS X. */
    @SuppressWarnings("unused")
00126       private static Object linkage;
    
    /** The framework to reference on Mac OS X */
    @SuppressWarnings("unused")
00130       private static final String JDirect_MacOSX = "/System/Library/Frameworks/Carbon.framework/Frameworks/HIToolbox.framework/HIToolbox";

    /** JVM constant for MRJ 2.0 */
00133     private static final int MRJ_2_0 = 0;
    
    /** JVM constant for MRJ 2.1 or later */
00136     private static final int MRJ_2_1 = 1;

    /** JVM constant for Java on Mac OS X 10.0 (MRJ 3.0) */
00139     private static final int MRJ_3_0 = 3;
    
    /** JVM constant for MRJ 3.1 */
00142     private static final int MRJ_3_1 = 4;

    /** JVM constant for any Windows NT JVM */
00145     private static final int WINDOWS_NT = 5;
    
    /** JVM constant for any Windows 9x JVM */
00148     private static final int WINDOWS_9x = 6;

    /** JVM constant for any Linux JVM */
00151     private static final int LINUX = 7;

    /** JVM constant for any other platform */
00154     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.
     */
00160     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.
     */
00166     private static final String FINDER_CREATOR = "MACS";

    /** The name for the AppleEvent type corresponding to a GetURL event. */
00169     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.
     */
00175     private static final String FIRST_WINDOWS_PARAMETER = "/c";
    
    /** The second parameter for Runtime.exec() on Windows. */
00178     private static final String SECOND_WINDOWS_PARAMETER = "start";
    
    /**
     * The third parameter for Runtime.exec() on Windows.  This is a "title"
     * parameter that the command line expects.  Setting this parameter allows
     * URLs containing spaces to work.
     */
00185     private static final String THIRD_WINDOWS_PARAMETER = "\"\"";
    
    /**
     * The shell parameters for Netscape that opens a given URL in an already-open copy of Netscape
     * on many command-line systems.
     */
00191     private static final String NETSCAPE_REMOTE_PARAMETER = "-remote";
    private static final String NETSCAPE_OPEN_PARAMETER_START = "'openURL(";
    private static final String NETSCAPE_OPEN_PARAMETER_END = ")'";
    
    /**
     * The message from any exception thrown throughout the initialization process.
     */
00198     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 (osName.startsWith("Mac OS")) {
            String mrjVersion = System.getProperty("mrj.version");
            String majorMRJVersion = mrjVersion.substring(0, 3);
            try {
                double version = Double.valueOf(majorMRJVersion).doubleValue();
                if (version == 2) {
                    jvm = MRJ_2_0;
                } else if (version >= 2.1 && version < 3) {
                    // Assume that all 2.x versions of MRJ work the same.  MRJ 2.1 actually
                    // works via Runtime.exec() and 2.2 supports that but has an openURL() method
                    // as well that we currently ignore.
                    jvm = MRJ_2_1;
                } else if (version == 3.0) {
                    jvm = MRJ_3_0;
                } else if (version >= 3.1) {
                    // Assume that all 3.1 and later versions of MRJ work the same.
                    jvm = MRJ_3_1;
                } else {
                    loadedWithoutErrors = false;
                    errorMessage = "Unsupported MRJ version: " + version;
                }
            } catch (NumberFormatException nfe) {
                loadedWithoutErrors = false;
                errorMessage = "Invalid MRJ version: " + mrjVersion;
            }
        } else if (osName.startsWith("Windows")) {
            if (osName.indexOf("9") != -1) {
                jvm = WINDOWS_9x;
            } else {
                jvm = WINDOWS_NT;
            }
        } else if (osName.startsWith("Linux")) {
          jvm = LINUX;
        }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.
     */
00252     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
     */
00260     private static boolean loadClasses() {
        switch (jvm) {
            case MRJ_2_0:
                try {
                    Class<?> aeTargetClass = Class.forName("com.apple.MacOS.AETarget");
                    Class<?> osUtilsClass = Class.forName("com.apple.MacOS.OSUtils");
                    Class<?> appleEventClass = Class.forName("com.apple.MacOS.AppleEvent");
                    Class<?> aeClass = Class.forName("com.apple.MacOS.ae");
                    aeDescClass = Class.forName("com.apple.MacOS.AEDesc");

                    aeTargetConstructor = aeTargetClass.getDeclaredConstructor(new Class [] { int.class });
                    appleEventConstructor = appleEventClass.getDeclaredConstructor(new Class[] { int.class, int.class, aeTargetClass, int.class, int.class });
                    aeDescConstructor = aeDescClass.getDeclaredConstructor(new Class[] { String.class });

                    makeOSType = osUtilsClass.getDeclaredMethod("makeOSType", new Class [] { String.class });
                    putParameter = appleEventClass.getDeclaredMethod("putParameter", new Class[] { int.class, aeDescClass });
                    sendNoReply = appleEventClass.getDeclaredMethod("sendNoReply", new Class[] { });

                    Field keyDirectObjectField = aeClass.getDeclaredField("keyDirectObject");
                    keyDirectObject = (Integer) keyDirectObjectField.get(null);
                    Field autoGenerateReturnIDField = appleEventClass.getDeclaredField("kAutoGenerateReturnID");
                    kAutoGenerateReturnID = (Integer) autoGenerateReturnIDField.get(null);
                    Field anyTransactionIDField = appleEventClass.getDeclaredField("kAnyTransactionID");
                    kAnyTransactionID = (Integer) anyTransactionIDField.get(null);
                } catch (ClassNotFoundException cnfe) {
                    errorMessage = cnfe.getMessage();
                    return false;
                } catch (NoSuchMethodException nsme) {
                    errorMessage = nsme.getMessage();
                    return false;
                } catch (NoSuchFieldException nsfe) {
                    errorMessage = nsfe.getMessage();
                    return false;
                } catch (IllegalAccessException iae) {
                    errorMessage = iae.getMessage();
                    return false;
                }
                break;
            case MRJ_2_1:
                try {
                    mrjFileUtilsClass = Class.forName("com.apple.mrj.MRJFileUtils");
                    mrjOSTypeClass = Class.forName("com.apple.mrj.MRJOSType");
                    Field systemFolderField = mrjFileUtilsClass.getDeclaredField("kSystemFolderType");
                    kSystemFolderType = systemFolderField.get(null);
                    findFolder = mrjFileUtilsClass.getDeclaredMethod("findFolder", new Class[] { mrjOSTypeClass });
                    getFileCreator = mrjFileUtilsClass.getDeclaredMethod("getFileCreator", new Class[] { File.class });
                    getFileType = mrjFileUtilsClass.getDeclaredMethod("getFileType", new Class[] { File.class });
                } catch (ClassNotFoundException cnfe) {
                    errorMessage = cnfe.getMessage();
                    return false;
                } catch (NoSuchFieldException nsfe) {
                    errorMessage = nsfe.getMessage();
                    return false;
                } catch (NoSuchMethodException nsme) {
                    errorMessage = nsme.getMessage();
                    return false;
                } catch (SecurityException se) {
                    errorMessage = se.getMessage();
                    return false;
                } catch (IllegalAccessException iae) {
                    errorMessage = iae.getMessage();
                    return false;
                }
                break;
            case MRJ_3_0:
                try {
                    Class<?> linker = Class.forName("com.apple.mrj.jdirect.Linker");
                    Constructor<?> constructor = linker.getConstructor(new Class[]{ Class.class });
                    linkage = constructor.newInstance(new Object[] { BrowserLauncher.class });
                } catch (ClassNotFoundException cnfe) {
                    errorMessage = cnfe.getMessage();
                    return false;
                } catch (NoSuchMethodException nsme) {
                    errorMessage = nsme.getMessage();
                    return false;
                } catch (InvocationTargetException ite) {
                    errorMessage = ite.getMessage();
                    return false;
                } catch (InstantiationException ie) {
                    errorMessage = ie.getMessage();
                    return false;
                } catch (IllegalAccessException iae) {
                    errorMessage = iae.getMessage();
                    return false;
                }
                break;
            case MRJ_3_1:
                try {
                    mrjFileUtilsClass = Class.forName("com.apple.mrj.MRJFileUtils");
                    openURL = mrjFileUtilsClass.getDeclaredMethod("openURL", new Class[] { String.class });
                } catch (ClassNotFoundException cnfe) {
                    errorMessage = cnfe.getMessage();
                    return false;
                } catch (NoSuchMethodException nsme) {
                    errorMessage = nsme.getMessage();
                    return false;
                }
                break;
            default:
                break;
        }
        return true;
    }

    /**
     * Attempts to locate the default web browser on the local system.  Caches results so it
     * only locates the browser once for each use of this class per JVM instance.
     * @return The browser for the system.  Note that this may not be what you would consider
     *          to be a standard web browser; instead, it's the application that gets called to
     *          open the default web browser.  In some cases, this will be a non-String object
     *          that provides the means of calling the default browser.
     */
00372     private static Object locateBrowser() {
        if (browser != null) {
            return browser;
        }
        switch (jvm) {
            case MRJ_2_0:
                try {
                    Integer finderCreatorCode = (Integer) makeOSType.invoke(null, new Object[] { FINDER_CREATOR });
                    Object aeTarget = aeTargetConstructor.newInstance(new Object[] { finderCreatorCode });
                    Integer gurlType = (Integer) makeOSType.invoke(null, new Object[] { GURL_EVENT });
                    Object appleEvent = appleEventConstructor.newInstance(new Object[] { gurlType, gurlType, aeTarget, kAutoGenerateReturnID, kAnyTransactionID });
                    // Don't set browser = appleEvent because then the next time we call
                    // locateBrowser(), we'll get the same AppleEvent, to which we'll already have
                    // added the relevant parameter. Instead, regenerate the AppleEvent every time.
                    // There's probably a way to do this better; if any has any ideas, please let
                    // me know.
                    return appleEvent;
                } catch (IllegalAccessException iae) {
                    browser = null;
                    errorMessage = iae.getMessage();
                    return browser;
                } catch (InstantiationException ie) {
                    browser = null;
                    errorMessage = ie.getMessage();
                    return browser;
                } catch (InvocationTargetException ite) {
                    browser = null;
                    errorMessage = ite.getMessage();
                    return browser;
                }
            case MRJ_2_1:
                File systemFolder;
                try {
                    systemFolder = (File) findFolder.invoke(null, new Object[] { kSystemFolderType });
                } catch (IllegalArgumentException iare) {
                    browser = null;
                    errorMessage = iare.getMessage();
                    return browser;
                } catch (IllegalAccessException iae) {
                    browser = null;
                    errorMessage = iae.getMessage();
                    return browser;
                } catch (InvocationTargetException ite) {
                    browser = null;
                    errorMessage = ite.getTargetException().getClass() + ": " + ite.getTargetException().getMessage();
                    return browser;
                }
                String[] systemFolderFiles = systemFolder.list();
                // Avoid a FilenameFilter because that can't be stopped mid-list
                for(int i = 0; i < systemFolderFiles.length; i++) {
                    try {
                        File file = new File(systemFolder, systemFolderFiles[i]);
                        if (!file.isFile()) {
                            continue;
                        }
                        // We're looking for a file with a creator code of 'MACS' and
                        // a type of 'FNDR'.  Only requiring the type results in non-Finder
                        // applications being picked up on certain Mac OS 9 systems,
                        // especially German ones, and sending a GURL event to those
                        // applications results in a logout under Multiple Users.
                        Object fileType = getFileType.invoke(null, new Object[] { file });
                        if (FINDER_TYPE.equals(fileType.toString())) {
                            Object fileCreator = getFileCreator.invoke(null, new Object[] { file });
                            if (FINDER_CREATOR.equals(fileCreator.toString())) {
                                browser = file.toString();  // Actually the Finder, but that's OK
                                return browser;
                            }
                        }
                    } catch (IllegalArgumentException iare) {
                        // browser = browser;
                        errorMessage = iare.getMessage();
                        return null;
                    } catch (IllegalAccessException iae) {
                        browser = null;
                        errorMessage = iae.getMessage();
                        return browser;
                    } catch (InvocationTargetException ite) {
                        browser = null;
                        errorMessage = ite.getTargetException().getClass() + ": " + ite.getTargetException().getMessage();
                        return browser;
                    }
                }
                browser = null;
                break;
            case MRJ_3_0:
            case MRJ_3_1:
                browser = "";   // Return something non-null
                break;
            case WINDOWS_NT:
                browser = "cmd.exe";
                break;
            case WINDOWS_9x:
                browser = "command.com";
                break;
            case LINUX:
            if ((new File("/usr/bin/mozilla")).exists())
                browser = "mozilla";
            else if ((new File("/usr/bin/firefox")).exists())
                browser = "firefox";
            else
                browser = "mozilla";
                break;
            case OTHER:
            default:
                browser = "netscape";
                break;
        }
        return browser;
    }

    /**
     * Attempts to open the default web browser to the given URL.
     * @param url The URL to open
     * @throws IOException If the web browser could not be located or does not run
     */
00487     public static void openURL(String url) throws IOException {
        if (!loadedWithoutErrors) {
            throw new IOException("Exception in finding browser: " + errorMessage);
        }
        Object browser = locateBrowser();
        if (browser == null) {
            throw new IOException("Unable to locate browser: " + errorMessage);
        }
        
        switch (jvm) {
            case MRJ_2_0:
                Object aeDesc = null;
                try {
                    aeDesc = aeDescConstructor.newInstance(new Object[] { url });
                    putParameter.invoke(browser, new Object[] { keyDirectObject, aeDesc });
                    sendNoReply.invoke(browser, new Object[] { });
                } catch (InvocationTargetException ite) {
                    throw new IOException("InvocationTargetException while creating AEDesc: " + ite.getMessage());
                } catch (IllegalAccessException iae) {
                    throw new IOException("IllegalAccessException while building AppleEvent: " + iae.getMessage());
                } catch (InstantiationException ie) {
                    throw new IOException("InstantiationException while creating AEDesc: " + ie.getMessage());
                } finally {
                    aeDesc = null;  // Encourage it to get disposed if it was created
                    browser = null; // Ditto
                }
                break;
            case MRJ_2_1:
                Runtime.getRuntime().exec(new String[] { (String) browser, url } );
                break;
            case MRJ_3_0:
                int[] instance = new int[1];
                int result = ICStart(instance, 0);
                if (result == 0) {
                    int[] selectionStart = new int[] { 0 };
                    byte[] urlBytes = url.getBytes();
                    int[] selectionEnd = new int[] { urlBytes.length };
                    result = ICLaunchURL(instance[0], new byte[] { 0 }, urlBytes,
                                            urlBytes.length, selectionStart,
                                            selectionEnd);
                    if (result == 0) {
                        // Ignore the return value; the URL was launched successfully
                        // regardless of what happens here.
                        ICStop(instance);
                    } else {
                        throw new IOException("Unable to launch URL: " + result);
                    }
                } else {
                    throw new IOException("Unable to create an Internet Config instance: " + result);
                }
                break;
            case MRJ_3_1:
                try {
                    openURL.invoke(null, new Object[] { url });
                } catch (InvocationTargetException ite) {
                    throw new IOException("InvocationTargetException while calling openURL: " + ite.getMessage());
                } catch (IllegalAccessException iae) {
                    throw new IOException("IllegalAccessException while calling openURL: " + iae.getMessage());
                }
                break;
            case WINDOWS_NT:
            case WINDOWS_9x:
                // Add quotes around the URL to allow ampersands and other special
                // characters to work.
                Process process = Runtime.getRuntime().exec(new String[] { (String) browser,
                                                                FIRST_WINDOWS_PARAMETER,
                                                                SECOND_WINDOWS_PARAMETER,
                                                                THIRD_WINDOWS_PARAMETER,
                                                                '"' + url + '"' });
                // This avoids a memory leak on some versions of Java on Windows.
                // That's hinted at in <http://developer.java.sun.com/developer/qow/archive/68/>.
                try {
                    process.waitFor();
                    process.exitValue();
                } catch (InterruptedException ie) {
                    throw new IOException("InterruptedException while launching browser: " + ie.getMessage());
                }
                break;
            case OTHER:
                // Assume that we're on Unix and that Netscape is installed
                
                // First, attempt to open the URL in a currently running session of Netscape
                process = Runtime.getRuntime().exec(new String[] { (String) browser,
                                                    NETSCAPE_REMOTE_PARAMETER,
                                                    NETSCAPE_OPEN_PARAMETER_START +
                                                    url +
                                                    NETSCAPE_OPEN_PARAMETER_END });
                try {
                    int exitCode = process.waitFor();
                    if (exitCode != 0) {    // if Netscape was not open
                        Runtime.getRuntime().exec(new String[] { (String) browser, url });
                    }
                } catch (InterruptedException ie) {
                    throw new IOException("InterruptedException while launching browser: " + ie.getMessage());
                }
                break;
            default:
                // This should never occur, but if it does, we'll try the simplest thing possible
                Runtime.getRuntime().exec(new String[] { (String) browser, url });
                break;
        }
    }

    /**
     * Methods required for Mac OS X.  The presence of native methods does not cause
     * any problems on other platforms.
     */
    private native static int ICStart(int[] instance, int signature);
    private native static int ICStop(int[] instance);
    private native static int ICLaunchURL(int instance, byte[] hint, byte[] data, int len,
                                            int[] selectionStart, int[] selectionEnd);
}

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