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Class BrowserLauncher  view BrowserLauncher download BrowserLauncher.java

java.lang.Object
  extended bypspdash.BrowserLauncher

public class BrowserLauncher
extends java.lang.Object

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

Version:
1.4b1 (Released June 20, 2001)

Field Summary
private static java.lang.Class aeDescClass
          The com.apple.MacOS.AEDesc class
private static java.lang.reflect.Constructor aeDescConstructor
          The (String) method of com.apple.MacOS.AEDesc
private static java.lang.reflect.Constructor aeTargetConstructor
          The (int) method of com.apple.MacOS.AETarget
private static java.lang.reflect.Constructor appleEventConstructor
          The (int, int, int) method of com.apple.MacOS.AppleEvent
private static java.lang.Object browser
          The browser for the system
private static java.lang.String errorMessage
          The message from any exception thrown throughout the initialization process.
private static java.lang.String FINDER_CREATOR
          The creator code of the Finder on a Macintosh, which is needed to send AppleEvents to the application.
private static java.lang.String FINDER_TYPE
          The file type of the Finder on a Macintosh.
private static java.lang.reflect.Method findFolder
          The findFolder method of com.apple.mrj.MRJFileUtils
private static java.lang.String FIRST_WINDOWS_PARAMETER
          The first parameter that needs to be passed into Runtime.exec() to open the default web browser on Windows.
private static java.lang.reflect.Method getFileCreator
          The getFileCreator method of com.apple.mrj.MRJFileUtils
private static java.lang.reflect.Method getFileType
          The getFileType method of com.apple.mrj.MRJFileUtils
private static java.lang.String GURL_EVENT
          The name for the AppleEvent type corresponding to a GetURL event.
private static java.lang.String JDirect_MacOSX
          The framework to reference on Mac OS X
private static int jvm
          The Java virtual machine that we are running on.
private static java.lang.Integer kAnyTransactionID
          The kAnyTransactionID AppleEvent code
private static java.lang.Integer kAutoGenerateReturnID
          The kAutoGenerateReturnID AppleEvent code
private static java.lang.Integer keyDirectObject
          The keyDirectObject AppleEvent parameter type
private static java.lang.Object kSystemFolderType
          Actually an MRJOSType pointing to the System Folder on a Macintosh
private static java.lang.Object linkage
          The linkage object required for JDirect 3 on Mac OS X.
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.
private static java.lang.reflect.Method makeOSType
          The makeOSType method of com.apple.MacOS.OSUtils
private static int MRJ_2_0
          JVM constant for MRJ 2.0
private static int MRJ_2_1
          JVM constant for MRJ 2.1 or later
private static int MRJ_3_0
          JVM constant for Java on Mac OS X 10.0 (MRJ 3.0)
private static int MRJ_3_1
          JVM constant for MRJ 3.1
private static java.lang.Class mrjFileUtilsClass
          The com.apple.mrj.MRJFileUtils class
private static java.lang.Class mrjOSTypeClass
          The com.apple.mrj.MRJOSType class
private static java.lang.String NETSCAPE_OPEN_PARAMETER_END
           
private static java.lang.String NETSCAPE_OPEN_PARAMETER_START
           
private static java.lang.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.
private static java.lang.reflect.Method openURL
          The openURL method of com.apple.mrj.MRJFileUtils
private static int OTHER
          JVM constant for any other platform
private static java.lang.reflect.Method putParameter
          The putParameter method of com.apple.MacOS.AppleEvent
private static java.lang.String SECOND_WINDOWS_PARAMETER
          The second parameter for Runtime.exec() on Windows.
private static java.lang.reflect.Method sendNoReply
          The sendNoReply method of com.apple.MacOS.AppleEvent
private static java.lang.String THIRD_WINDOWS_PARAMETER
          The third parameter for Runtime.exec() on Windows.
private static int WINDOWS_9x
          JVM constant for any Windows 9x JVM
private static int WINDOWS_NT
          JVM constant for any Windows NT JVM
 
Constructor Summary
private BrowserLauncher()
          This class should be never be instantiated; this just ensures so.
 
Method Summary
private static int ICLaunchURL(int instance, byte[] hint, byte[] data, int len, int[] selectionStart, int[] selectionEnd)
           
private static int ICStart(int[] instance, int signature)
          Methods required for Mac OS X.
private static int ICStop(int[] instance)
           
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.
private static java.lang.Object locateBrowser()
          Attempts to locate the default web browser on the local system.
static void openURL(java.lang.String url)
          Attempts to open the default web browser to the given URL.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

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.


browser

private static java.lang.Object browser
The browser for the system


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.


mrjFileUtilsClass

private static java.lang.Class mrjFileUtilsClass
The com.apple.mrj.MRJFileUtils class


mrjOSTypeClass

private static java.lang.Class mrjOSTypeClass
The com.apple.mrj.MRJOSType class


aeDescClass

private static java.lang.Class aeDescClass
The com.apple.MacOS.AEDesc class


aeTargetConstructor

private static java.lang.reflect.Constructor aeTargetConstructor
The (int) method of com.apple.MacOS.AETarget


appleEventConstructor

private static java.lang.reflect.Constructor appleEventConstructor
The (int, int, int) method of com.apple.MacOS.AppleEvent


aeDescConstructor

private static java.lang.reflect.Constructor aeDescConstructor
The (String) method of com.apple.MacOS.AEDesc


findFolder

private static java.lang.reflect.Method findFolder
The findFolder method of com.apple.mrj.MRJFileUtils


getFileCreator

private static java.lang.reflect.Method getFileCreator
The getFileCreator method of com.apple.mrj.MRJFileUtils


getFileType

private static java.lang.reflect.Method getFileType
The getFileType method of com.apple.mrj.MRJFileUtils


openURL

private static java.lang.reflect.Method openURL
The openURL method of com.apple.mrj.MRJFileUtils


makeOSType

private static java.lang.reflect.Method makeOSType
The makeOSType method of com.apple.MacOS.OSUtils


putParameter

private static java.lang.reflect.Method putParameter
The putParameter method of com.apple.MacOS.AppleEvent


sendNoReply

private static java.lang.reflect.Method sendNoReply
The sendNoReply method of com.apple.MacOS.AppleEvent


kSystemFolderType

private static java.lang.Object kSystemFolderType
Actually an MRJOSType pointing to the System Folder on a Macintosh


keyDirectObject

private static java.lang.Integer keyDirectObject
The keyDirectObject AppleEvent parameter type


kAutoGenerateReturnID

private static java.lang.Integer kAutoGenerateReturnID
The kAutoGenerateReturnID AppleEvent code


kAnyTransactionID

private static java.lang.Integer kAnyTransactionID
The kAnyTransactionID AppleEvent code


linkage

private static java.lang.Object linkage
The linkage object required for JDirect 3 on Mac OS X.


JDirect_MacOSX

private static final java.lang.String JDirect_MacOSX
The framework to reference on Mac OS X

See Also:
Constant Field Values

MRJ_2_0

private static final int MRJ_2_0
JVM constant for MRJ 2.0

See Also:
Constant Field Values

MRJ_2_1

private static final int MRJ_2_1
JVM constant for MRJ 2.1 or later

See Also:
Constant Field Values

MRJ_3_0

private static final int MRJ_3_0
JVM constant for Java on Mac OS X 10.0 (MRJ 3.0)

See Also:
Constant Field Values

MRJ_3_1

private static final int MRJ_3_1
JVM constant for MRJ 3.1

See Also:
Constant Field Values

WINDOWS_NT

private static final int WINDOWS_NT
JVM constant for any Windows NT JVM

See Also:
Constant Field Values

WINDOWS_9x

private static final int WINDOWS_9x
JVM constant for any Windows 9x JVM

See Also:
Constant Field Values

OTHER

private static final int OTHER
JVM constant for any other platform

See Also:
Constant Field Values

FINDER_TYPE

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

See Also:
Constant Field Values

FINDER_CREATOR

private static final java.lang.String FINDER_CREATOR
The creator code of the Finder on a Macintosh, which is needed to send AppleEvents to the application.

See Also:
Constant Field Values

GURL_EVENT

private static final java.lang.String GURL_EVENT
The name for the AppleEvent type corresponding to a GetURL event.

See Also:
Constant Field Values

FIRST_WINDOWS_PARAMETER

private static final java.lang.String FIRST_WINDOWS_PARAMETER
The first parameter that needs to be passed into Runtime.exec() to open the default web browser on Windows.

See Also:
Constant Field Values

SECOND_WINDOWS_PARAMETER

private static final java.lang.String SECOND_WINDOWS_PARAMETER
The second parameter for Runtime.exec() on Windows.

See Also:
Constant Field Values

THIRD_WINDOWS_PARAMETER

private static final java.lang.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.

See Also:
Constant Field Values

NETSCAPE_REMOTE_PARAMETER

private static final java.lang.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.

See Also:
Constant Field Values

NETSCAPE_OPEN_PARAMETER_START

private static final java.lang.String NETSCAPE_OPEN_PARAMETER_START
See Also:
Constant Field Values

NETSCAPE_OPEN_PARAMETER_END

private static final java.lang.String NETSCAPE_OPEN_PARAMETER_END
See Also:
Constant Field Values

errorMessage

private static java.lang.String errorMessage
The message from any exception thrown throughout the initialization process.

Constructor Detail

BrowserLauncher

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

Method Detail

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.


locateBrowser

private static java.lang.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.


openURL

public static void openURL(java.lang.String url)
                    throws java.io.IOException
Attempts to open the default web browser to the given URL.


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)

ICLaunchURL

private static int ICLaunchURL(int instance,
                               byte[] hint,
                               byte[] data,
                               int len,
                               int[] selectionStart,
                               int[] selectionEnd)