package.java

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	if (l != null) {
	    return l.getPackage(name);
	} else {
	    return getSystemPackage(name);
	}
    }

    /**
     * Get all the packages currently known for the caller's <code>ClassLoader</code>
     * instance.  Those packages correspond to classes loaded via or accessible by
     * name to that <code>ClassLoader</code> instance.  If the caller's
     * <code>ClassLoader</code> instance is the bootstrap <code>ClassLoader</code>
     * instance, which may be represented by <code>null</code> in some implementations,
     * only packages corresponding to classes loaded by the bootstrap
     * <code>ClassLoader</code> instance will be returned.
     *
     * @return a new array of packages known to the callers <code>ClassLoader</code>
     * instance.  An zero length array is returned if none are known.
     */
    public static Package[] getPackages() {
	ClassLoader l = ClassLoader.getCallerClassLoader();
	if (l != null) {
	    return l.getPackages();
	} else {
	    return getSystemPackages();
	}
    }

    /**
     * Get the package for the specified class.
     * The class's class loader is used to find the package instance
     * corresponding to the specified class. If the class loader
     * is the bootstrap class loader, which may be represented by
     * <code>null</code> in some implementations, then the set of packages
     * loaded by the bootstrap class loader is searched to find the package.
     * <p>
     * Packages have attributes for versions and specifications only
     * if the class loader created the package
     * instance with the appropriate attributes. Typically those
     * attributes are defined in the manifests that accompany
     * the classes.
     *
     * @param class the class to get the package of.
     * @return the package of the class. It may be null if no package
     * 		information is available from the archive or codebase.  */
    static Package getPackage(Class c) {
	String name = c.getName();
	int i = name.lastIndexOf('.');
	if (i != -1) {
	    name = name.substring(0, i);
	    ClassLoader cl = c.getClassLoader();
	    if (cl != null) {
		return cl.getPackage(name);
	    } else {
		return getSystemPackage(name);
	    }
	} else {
	    return null;
	}
    }

    /**
     * Return the hash code computed from the package name.
     * @return the hash code computed from the package name.
     */
    public int hashCode(){
    	return pkgName.hashCode();
    }

    /**
     * Returns the string representation of this Package.
     * Its value is the string "package " and the package name.
     * If the package title is defined it is appended.
     * If the package version is defined it is appended.
     * @return the string representation of the package.
     */
    public String toString() {
	String spec = specTitle;
	String ver =  specVersion;
	if (spec != null && spec.length() > 0)
	    spec = ", " + spec;
	else
	    spec = "";
	if (ver != null && ver.length() > 0)
	    ver = ", version " + ver;
	else
	    ver = "";
	return "package " + pkgName + spec + ver;
    }

    /**
     * Construct a package instance with the specified version
     * information.
     * @param pkgName the name of the package
     * @param spectitle the title of the specification
     * @param specversion the version of the specification
     * @param specvendor the organization that maintains the specification
     * @param impltitle the title of the implementation
     * @param implversion the version of the implementation
     * @param implvendor the organization that maintains the implementation
     * @return a new package for containing the specified information.
     */
    Package(String name,
	    String spectitle, String specversion, String specvendor,
	    String impltitle, String implversion, String implvendor,
	    URL sealbase)
    {
    	pkgName = name;
	implTitle = impltitle;
	implVersion = implversion;
	implVendor = implvendor;
	specTitle = spectitle;
	specVersion = specversion;
	specVendor = specvendor;
	sealBase = sealbase;
    }

    /*
     * Construct a package using the attributes from the specified manifest.
     *
     * @param name the package name
     * @param man the optional manifest for the package
     * @param url the optional code source url for the package
     */
    private Package(String name, Manifest man, URL url) {
	String path = name.replace('.', '/').concat("/");
	String sealed = null;
	Attributes attr = man.getAttributes(path);
	if (attr != null) {
	    specTitle   = attr.getValue(Name.SPECIFICATION_TITLE);
	    specVersion = attr.getValue(Name.SPECIFICATION_VERSION);
	    specVendor  = attr.getValue(Name.SPECIFICATION_VENDOR);
	    implTitle   = attr.getValue(Name.IMPLEMENTATION_TITLE);
	    implVersion = attr.getValue(Name.IMPLEMENTATION_VERSION);
	    implVendor  = attr.getValue(Name.IMPLEMENTATION_VENDOR);
	    sealed      = attr.getValue(Name.SEALED);
	}
	attr = man.getMainAttributes();
	if (attr != null) {
	    if (specTitle == null) {
		specTitle = attr.getValue(Name.SPECIFICATION_TITLE);
	    }
	    if (specVersion == null) {
		specVersion = attr.getValue(Name.SPECIFICATION_VERSION);
	    }
	    if (specVendor == null) {
		specVendor = attr.getValue(Name.SPECIFICATION_VENDOR);
	    }
	    if (implTitle == null) {
		implTitle = attr.getValue(Name.IMPLEMENTATION_TITLE);
	    }
	    if (implVersion == null) {
		implVersion = attr.getValue(Name.IMPLEMENTATION_VERSION);
	    }
	    if (implVendor == null) {
		implVendor = attr.getValue(Name.IMPLEMENTATION_VENDOR);
	    }
	    if (sealed == null) {
		sealed = attr.getValue(Name.SEALED);
	    }
	}
	if ("true".equalsIgnoreCase(sealed)) {
	    sealBase = url;
	}
	pkgName = name;
    }

    /*
     * Returns the loaded system package for the specified name.
     */
    static Package getSystemPackage(String name) {
	synchronized (pkgs) {
	    Package pkg = (Package)pkgs.get(name);
	    if (pkg == null) {
		name = name.replace('.', '/').concat("/");
		String fn = getSystemPackage0(name);
		if (fn != null) {
		    pkg = defineSystemPackage(name, fn);
		}
	    }
	    return pkg;
	}
    }

    /*
     * Return an array of loaded system packages.
     */
    static Package[] getSystemPackages() {
	// First, update the system package map with new package names
	String[] names = getSystemPackages0();
	synchronized (pkgs) {
	    for (int i = 0; i < names.length; i++) {
		defineSystemPackage(names[i], getSystemPackage0(names[i]));
	    }
	    return (Package[])pkgs.values().toArray(new Package[pkgs.size()]);
	}
    }

    private static Package defineSystemPackage(final String iname,
					       final String fn)
    {
	return (Package) AccessController.doPrivileged(new PrivilegedAction() {
	    public Object run() {
		String name = iname;
		// Get the cached code source url for the file name
		URL url = (URL)urls.get(fn);
		if (url == null) {
		    // URL not found, so create one
		    File file = new File(fn);
		    try {
			url = ParseUtil.fileToEncodedURL(file);
		    } catch (MalformedURLException e) {
		    }
		    if (url != null) {
			urls.put(fn, url);
			// If loading a JAR file, then also cache the manifest
			if (file.isFile()) {
			    mans.put(fn, loadManifest(fn));
			}
		    }
		}
		// Convert to "."-separated package name
		name = name.substring(0, name.length() - 1).replace('/', '.');
		Package pkg;
		Manifest man = (Manifest)mans.get(fn);
		if (man != null) {
		    pkg = new Package(name, man, url);
		} else {
		    pkg = new Package(name, null, null, null,
				      null, null, null, null);
		}
		pkgs.put(name, pkg);
		return pkg;
	    }
	});
    }

    /*
     * Returns the Manifest for the specified JAR file name.
     */
    private static Manifest loadManifest(String fn) {
	try {
	    FileInputStream fis = new FileInputStream(fn);
	    JarInputStream jis = new JarInputStream(fis, false);
	    Manifest man = jis.getManifest();
	    jis.close();
	    return man;
	} catch (IOException e) {
	    return null;
	}
    }

    // The map of loaded system packages
    private static Map pkgs = new HashMap(31);

    // Maps each directory or zip file name to its corresponding url
    private static Map urls = new HashMap(10);

    // Maps each code source url for a jar file to its manifest
    private static Map mans = new HashMap(10);

    private static native String getSystemPackage0(String name);
    private static native String[] getSystemPackages0();

    /*
     * Private storage for the package name and attributes.
     */
    private String pkgName;
    private String specTitle;
    private String specVersion;
    private String specVendor;
    private String implTitle;
    private String implVersion;
    private String implVendor;
    private URL sealBase;
}