ijce.java

jpeg2000编解码

            cl.getName() + error);
    }

    /**
     * Given an algorithm name (which may be an alias) and type, returns the
     * corresponding algorithm class from any provider.
     */
    public static Class
    getImplementationClass(String algorithm, String type)
    throws NoSuchAlgorithmException {
        try {
            return getImplementationClass(algorithm, null, type);
        } catch (NoSuchProviderException e) {
            throw new NoSuchAlgorithmException(e.getMessage());
        }
    }

    /**
     * Given an algorithm name (which may be an alias), a provider name, and
     * a type, returns the corresponding algorithm class.
     */
    public static Class
    getImplementationClass(String algorithm, String provider, String type)
    throws NoSuchAlgorithmException, NoSuchProviderException {

        String standardName = getStandardName(algorithm, type);
        Class target = getClassForType(type);
        if (target == null)
            throw new NoSuchAlgorithmException(type + " is not a configured type");

        Class cl = getClassCandidate(standardName, provider, type);

        // replace this with target.isAssignableFrom(cl) for a 1.1-only release.
        if (IJCE_Java10Support.isAssignableFrom(target, cl))
            return cl;

        throw new NoSuchAlgorithmException("class configured for " + type +
            ": " + cl.getName() + " is not a subclass of " + target.getName());
    }

    private static Class
    getClassCandidate(String standardName, String provider, String type)
    throws NoSuchAlgorithmException, NoSuchProviderException {
        String property = type + "." + standardName;

        if (provider == null) {
            String classname;
            Class cl;

            // the first class matching this name does not exist, so search all
            // providers.
            Provider[] providers = getProvidersInternal();
            for (int i = 0; i < providers.length; i++) {
                classname = providers[i].getProperty(property);
                if (classname != null) {
                    try {
                        cl = findEngineClass(classname, type);
                        if (cl != null)
                            return cl;
                    } catch (NoSuchAlgorithmException e) {}
                }
            }
            throw new NoSuchAlgorithmException("algorithm " + standardName +
                " is not available.");
        }

        Provider providerObj = getProviderInternal(provider);
        if (providerObj == null)
            throw new NoSuchProviderException("provider " + provider +
                " is not available.");

        String classname = providerObj.getProperty(property);
        if (classname != null) {
            Class cl = findEngineClass(classname, type);
            if (cl != null)
                return cl;
        }
        throw new NoSuchAlgorithmException("algorithm " + standardName +
            " is not available from provider " + provider);
    }

    private static Class
    findEngineClass(String classname, String type)
    throws NoSuchAlgorithmException {
        String error;
        try {
            return Class.forName(classname);
        } catch (ClassNotFoundException e) {
            return null;
        } catch (NoSuchMethodError e) {
            error = " does not have a zero-argument constructor.\n" + e;
        } catch (LinkageError e) {
            error = " could not be linked correctly.\n" + e;
        }
        throw new NoSuchAlgorithmException("class configured for " + type + ": " +
            classname + error);
    }
    
    /**
     * Returns a Target that can be passed to
     * <code>PrivilegeManager.enablePrivilege(...)</code>, in order to request
     * permission for an action that requires the user's trust.
     * <p>
     * Currently the following target names are recognized:
     * <ul>
     *   <li> AddSecurityProvider - add a new security provider to the system.
     *   <li> RemoveSecurityProvider - remove a security provider from the system.
     *   <li> SecurityPropertyRead - read the security properties.
     *   <li> SecurityPropertyWrite - change the value of any security property.
     *   <li> GetSecurityProviders - get a reference to any security Provider object.
     * </ul>
     *
     * @param name  the name of the target to be returned
     * @return the Target object
     * @exception ForbiddenTargetException if <i>name</i> is not recognized.
     */
    public static Target findTarget(String name)
    throws ForbiddenTargetException {
        return IJCE_SecuritySupport.findTarget(name);
    }

    /**
     * Reserved for future use, in case parameterized targets are needed. Currently
     * this always throws a ForbiddenTargetException.
     *
     * @param name  the name of the target to be returned
     * @param arg   a parameter object
     * @return the Target object
     * @exception ForbiddenTargetException if <i>name</i> is not recognized.
     */
    public static Target findTarget(String name, Object arg)
    throws ForbiddenTargetException {
        return IJCE_SecuritySupport.findTarget(name, arg);
    }

    /**
     * Returns the major version of this release of IJCE.
     */
    public static int getMajorVersion() { return MAJOR_VERSION; }

    /**
     * Returns the minor version of this release of IJCE.
     */
    public static int getMinorVersion() { return MINOR_VERSION; }

    /**
     * Returns the intermediate version of this release of IJCE.
     */
    public static int getIntermediateVersion() { return INTER_VERSION; }

    /**
     * Returns true iff this version of IJCE is at least the given
     * version.
     */
    public static boolean
    isVersionAtLeast(int major, int minor, int intermediate) {
        if (MAJOR_VERSION > major) return true;
        if (MAJOR_VERSION < major) return false;
        if (MINOR_VERSION > minor) return true;
        if (MINOR_VERSION < minor) return false;
        return INTER_VERSION >= intermediate;
    }

    /**
     * Returns the release date of this version of IJCE, as a string in
     * the form "yyyy/mm/dd".
     */
    public static String getReleaseDate() {
        try {
            return CVS_DATE.substring(7, 17);
        } catch (StringIndexOutOfBoundsException e) {
            return "unknown";
        }
    }

    /**
     * Returns a string describing this version of IJCE.
     */
    public static String getVersionString() {
        StringBuffer version = new StringBuffer("IJCE ")
            .append(MAJOR_VERSION).append(".").append(MINOR_VERSION);
        if (INTER_VERSION != 0)
            version.append(".").append(INTER_VERSION);
        if (IS_SNAPSHOT)
            version.append(" (").append(getReleaseDate()).append(" snapshot)");

        return version.toString();
    }

    /**
     * Returns true if IJCE is providing the implementations of the JCA classes
     * (MessageDigest, Signature, etc). This will be false if another version
     * of JCA (for example JavaSoft's) is installed earlier in the CLASSPATH.
     */
    public static boolean isProvidingJCA() {
        try {
            return IJCE_Java10Support.isAssignableFrom(
                Class.forName("java.security.IJCE_Traceable"),
                Class.forName("java.security.MessageDigest"));
        } catch (Exception e) { return false; }
    }

    /**
     * Returns true if IJCE is providing the implementations of the JCE classes
     * (Cipher, KeyGenerator, etc). This will be false if another version
     * of JCE (for example JavaSoft's) is installed earlier in the CLASSPATH.
     */
    public static boolean isProvidingJCE() {
        try {
            return IJCE_Java10Support.isAssignableFrom(
                Class.forName("java.security.IJCE_Traceable"),
                Class.forName("java.security.Cipher"));
        } catch (Exception e) { return false; }
    }


// Internal methods
//...........................................................................

    /**
     * Returns the algorithm superclass corresponding to <i>type</i>, or null
     * if there is no such class.
     * <p>
     * For example, normally <code>getClassForType("Cipher")</code> would
     * return <code>java.security.Cipher.class</code>.
     * Type names are configured in the IJCE.properties file.
     */
    private static Class getClassForType(String type) {
        Class cl = (Class) (typeToClass.get(type));
        if (cl != null)
            return cl;

        String classname = IJCE_Properties.getProperty("Type." + type);
        if (classname == null)
            return null;

        try {
            cl = Class.forName(classname);
        } catch (LinkageError e) {
            IJCE.debug("Error loading class for algorithm type " + type + ": " + e);
            return null;
        } catch (ClassNotFoundException e) {
            IJCE.debug("Error loading class for algorithm type " + type + ": " + e);
            return null;
        }
        typeToClass.put(type, cl);
        return cl;
    }

    /**
     * Helper method to get an array of all configured security Provider objects.
     * This method does not do a security check.
     *
     * @return an array of configured Provider objects.
     */
    private static Provider[] getProvidersInternal() {
        try {
            if (getProvidersTarget == null)
                getProvidersTarget = findTarget("GetSecurityProviders");
            if (privMgr == null)
                privMgr = PrivilegeManager.getPrivilegeManager();
          
            privMgr.enablePrivilege(getProvidersTarget);
        } catch (NoClassDefFoundError e) {}
    
        Provider[] providers = Security.getProviders();
        if (DEBUG && debuglevel >= 4) {
            for (int i = 0; i < providers.length; i++)
                debug("providers[" + i + "] = " + providers[i]);
        }

        try { privMgr.revertPrivilege(getProvidersTarget); }
        catch (NoClassDefFoundError e) {}

        return providers;
    }

    /**
     * Helper method to get a configured security Provider object by name.
     * This method does not do a security check.
     *
     * @return the Provider object for providerName.
     */
    private static Provider getProviderInternal(String providerName) {
        try {
            if (getProvidersTarget == null)
                getProvidersTarget = findTarget("GetSecurityProviders");
            if (privMgr == null)
                privMgr = PrivilegeManager.getPrivilegeManager();
          
            privMgr.enablePrivilege(getProvidersTarget);
        } catch (NoClassDefFoundError e) {}
    
        Provider provider = Security.getProvider(providerName);

        try { privMgr.revertPrivilege(getProvidersTarget); }
        catch (NoClassDefFoundError e) {}

        return provider;
    }

    /**
     * Prints a debugging message that may be significant to a developer.
     */
    static void debug(String s) { err.println(s); }

    /**
     * Prints an error message that may be significant to a user.
     */
    static void error(String s) { err.println(s); }

    /**
     * Prints a "can't happen" error, with a request to report this as a bug.
     * Always throws an InternalError.
     */
    static void reportBug(String s) {
        err.println(
            "\n" + s + "\n\n" +
            "Please report this as a bug to <[e-mail]>, including\n" +
            "any other messages displayed on the console, and a description of what\n" +
            "appeared to cause the error.\n");
        throw new InternalError(s);
    }

    /**
     * Debugging method to list all providers.
     */
    static void listProviders() {
        Provider[] providers = getProvidersInternal();
        for (int i = 0; i < providers.length; i++)
            err.println("providers[" + i + "] = " + providers[i]);
    }

    /**
     * Returns the debug level for <i>label</i>. Its value is normally given
     * by the numeric provider property "<code>Debug.Level.<i>label</i></code>".
     * <p>
     * If this property is not set, "<code>Debug.Level.*</code>" is
     * searched next. If neither property is set, or if the first property
     * found is not a valid decimal integer, then this method returns 0.
     */
    static int getDebugLevel(String label) {
        String s = IJCE_Properties.getProperty("Debug.Level." + label);
        if (s == null) {
            s = IJCE_Properties.getProperty("Debug.Level.*");
            if (s == null)
                return 0;
        }
        try { return Integer.parseInt(s); }
        catch (NumberFormatException e) { return 0; }
    }

    /**
     * Returns the PrintWriter that debugging Output is to be sent to.
     */
    static PrintWriter getDebugOutput() {
        return err;
    }


// Main
//...........................................................................

    /**
     * Prints the IJCE version string, a list of statically configured providers,
     * and the location of the library directory.
     */
    public static void main(String[] args) {
        System.out.println(getVersionString());
        System.out.println();
        listProviders();
        System.out.println();
        try {
            String libPath = IJCE_Properties.getLibraryPath();
            System.out.println("The library directory is");
            System.out.println("  " + libPath);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}