Java tutorial
/* * This code is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * 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 Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this program; if not, write to the Free * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, * MA 02111-1307, USA. */ //package no.geosoft.cc.io; import java.io.File; import java.io.FileNotFoundException; import java.io.IOException; import java.net.URL; import java.lang.reflect.Constructor; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; /** * Browser 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) * * @author <a href="mailto:jacob.dreyer@geosoft.no">Jacob Dreyer</a> * Added methods to the API and adjusted the linux version slightly. */ public class Browser { /** * 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.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 getFileCreator method of com.apple.mrj.MRJFileUtils */ private static Method getFileCreator; /** The getFileType method of com.apple.mrj.MRJFileUtils */ private static Method getFileType; /** The openURL method of com.apple.mrj.MRJFileUtils */ private static Method openURL; /** 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; /** The linkage object required for JDirect 3 on Mac OS X. */ private static Object linkage; /** The framework to reference on Mac OS X */ private static final String JDirect_MacOSX = "/System/Library/Frameworks/Carbon.framework/Frameworks/HIToolbox.framework/HIToolbox"; /** 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 Java on Mac OS X 10.0 (MRJ 3.0) */ private static final int MRJ_3_0 = 3; /** JVM constant for MRJ 3.1 */ private static final int MRJ_3_1 = 4; /** JVM constant for any Windows NT JVM */ private static final int WINDOWS_NT = 5; /** JVM constant for any Windows 9x JVM */ private static final int WINDOWS_9x = 6; /** 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 FIRST_WINDOWS_PARAMETER = "/c"; /** The second parameter for Runtime.exec() on Windows. */ 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. */ 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. */ 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. */ 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 { 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 Browser() { } /** * 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() { 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[] { Browser.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. */ 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; } // Avoid a FilenameFilter because that can't be stopped mid-list String[] systemFolderFiles = systemFolder.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())) { // Actually the Finder, but that's OK browser = file.toString(); 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 OTHER: default: browser = "netscape"; break; } return browser; } /** * Open the specified file in the client web browser. * * @param file File to open * @throws IOException If there is brwoser problem. * */ public static void openUrl(File file) throws IOException { openUrl("file://" + file.getPath()); } /** * Open the specified URL in the client web browser. * * @param url URL to open. * @throws IOException If there is brwoser problem. */ public static void openUrl(URL url) throws IOException { openUrl(url.toString()); } /** * Open the specified URL in the client web browser. * * @param url URL to open. * @throws IOException If there is brwoser problem. */ 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 String command = browser.toString() + " -raise " + NETSCAPE_REMOTE_PARAMETER + " " + NETSCAPE_OPEN_PARAMETER_START + url + NETSCAPE_OPEN_PARAMETER_END; process = Runtime.getRuntime().exec(command); try { int exitCode = process.waitFor(); if (exitCode != 0) { // if Netscape was not open Runtime.getRuntime().exec(new String[] { (String) browser, url }); } } catch (InterruptedException exception) { exception.printStackTrace(); throw new IOException("InterruptedException while launching browser: " + exception.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); }