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.
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.
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.
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.
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.
Credits:
Steven Spencer, JavaWorld magazine (
Java Tip 66)
Thanks also to Ron B. Yeh, Eric Shapiro, Ben Engber, Paul Teitlebaum, Andrea Cantatore,
Larry Barowski, Trevor Bedzek, Frank Miedrich, and Ron Rabakukk
FINDER_CREATOR
private static final String FINDER_CREATOR
The creator code of the Finder on a Macintosh, which is needed to send AppleEvents to the
application.
FINDER_TYPE
private static final String FINDER_TYPE
The file type of the Finder on a Macintosh. Hardcoding "Finder" would keep non-U.S. English
systems from working properly.
FIRST_WINDOWS_PARAMETER
private static final String FIRST_WINDOWS_PARAMETER
The first parameter that needs to be passed into Runtime.exec() to open the default web
browser on Windows.
GURL_EVENT
private static final String GURL_EVENT
The name for the AppleEvent type corresponding to a GetURL event.
JDirect_MacOSX
private static final String JDirect_MacOSX
The framework to reference on Mac OS X
MRJ_2_0
private static final int MRJ_2_0
JVM constant for MRJ 2.0
MRJ_2_1
private static final int MRJ_2_1
JVM constant for MRJ 2.1 or later
MRJ_3_0
private static final int MRJ_3_0
JVM constant for Java on Mac OS X 10.0 (MRJ 3.0)
MRJ_3_1
private static final int MRJ_3_1
JVM constant for MRJ 3.1
NETSCAPE_OPEN_PARAMETER_END
private static final String NETSCAPE_OPEN_PARAMETER_END
NETSCAPE_OPEN_PARAMETER_START
private static final String NETSCAPE_OPEN_PARAMETER_START
NETSCAPE_REMOTE_PARAMETER
private static final String NETSCAPE_REMOTE_PARAMETER
The shell parameters for Netscape that opens a given URL in an already-open copy of Netscape
on many command-line systems.
OTHER
private static final int OTHER
JVM constant for any other platform
SECOND_WINDOWS_PARAMETER
private static final String SECOND_WINDOWS_PARAMETER
The second parameter for Runtime.exec() on Windows.
THIRD_WINDOWS_PARAMETER
private static final String THIRD_WINDOWS_PARAMETER
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.
WINDOWS_9x
private static final int WINDOWS_9x
JVM constant for any Windows 9x JVM
WINDOWS_NT
private static final int WINDOWS_NT
JVM constant for any Windows NT JVM
aeDescClass
private static Class aeDescClass
The com.apple.MacOS.AEDesc class
aeDescConstructor
private static Constructor aeDescConstructor
The (String) method of com.apple.MacOS.AEDesc
aeTargetConstructor
private static Constructor aeTargetConstructor
The (int) method of com.apple.MacOS.AETarget
appleEventConstructor
private static Constructor appleEventConstructor
The (int, int, int) method of com.apple.MacOS.AppleEvent
browser
private static Object browser
The browser for the system
errorMessage
private static String errorMessage
The message from any exception thrown throughout the initialization process.
findFolder
private static Method findFolder
The findFolder method of com.apple.mrj.MRJFileUtils
getFileCreator
private static Method getFileCreator
The getFileCreator method of com.apple.mrj.MRJFileUtils
getFileType
private static Method getFileType
The getFileType method of com.apple.mrj.MRJFileUtils
jvm
private static int jvm
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.
kAnyTransactionID
private static Integer kAnyTransactionID
The kAnyTransactionID AppleEvent code
kAutoGenerateReturnID
private static Integer kAutoGenerateReturnID
The kAutoGenerateReturnID AppleEvent code
kSystemFolderType
private static Object kSystemFolderType
Actually an MRJOSType pointing to the System Folder on a Macintosh
keyDirectObject
private static Integer keyDirectObject
The keyDirectObject AppleEvent parameter type
linkage
private static Object linkage
The linkage object required for JDirect 3 on Mac OS X.
loadedWithoutErrors
private static boolean loadedWithoutErrors
Caches whether any classes, methods, and fields that are not part of the JDK and need to
be dynamically loaded at runtime loaded successfully.
Note that if this is
false,
openURL() will always return an
IOException.
makeOSType
private static Method makeOSType
The makeOSType method of com.apple.MacOS.OSUtils
mrjFileUtilsClass
private static Class mrjFileUtilsClass
The com.apple.mrj.MRJFileUtils class
mrjOSTypeClass
private static Class mrjOSTypeClass
The com.apple.mrj.MRJOSType class
openURL
private static Method openURL
The openURL method of com.apple.mrj.MRJFileUtils
putParameter
private static Method putParameter
The putParameter method of com.apple.MacOS.AppleEvent
sendNoReply
private static Method sendNoReply
The sendNoReply method of com.apple.MacOS.AppleEvent
ICLaunchURL
private static int ICLaunchURL(int instance,
byte[] hint,
byte[] data,
int len,
int[] selectionStart,
int[] selectionEnd)
ICStart
private static int ICStart(int[] instance,
int signature) Methods required for Mac OS X. The presence of native methods does not cause
any problems on other platforms.
ICStop
private static int ICStop(int[] instance)
loadClasses
private static boolean loadClasses()
Called by a static initializer to load any classes, fields, and methods required at runtime
to locate the user's web browser.
true if all intialization succeeded
false if any portion of the initialization failed
locateBrowser
private static Object locateBrowser()
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.
- 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.
openURL
public static void openURL(String url)
throws IOException Attempts to open the default web browser to the given URL.