browserlauncher.java

openmap java写的开源数字地图程序. 用applet实现,可以像google map 那样放大缩小地图.

package edu.stanford.ejalbert;

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 ([e-mail]) 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:[e-mail]">[e-mail]</a>)
 * @version 1.4b1 (Released June 20, 2001)
 */
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. */
    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; // Unused
        
    /** The framework to reference on Mac OS X, unused */
    //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 MRJ 4.1 */
    private static final int MRJ_4_1 = 7;

    /** 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.
                    // Bad assumption, they don't.
                    jvm = MRJ_3_1;
                } else if (version >= 4.1) {
                    // Assume that all 4.1 and later versions of MRJ work the same.
                    // Probably won't in the future.
                    jvm = MRJ_4_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 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
     */
    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");