Java/Development Class/System Browser

Access client web browser from java

/*
 * 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 
 * (
 * 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.ru";
        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.ru/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);
}