localutil.java

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     * @throws ClassNotFoundException If <code>className</code> is not valid
     */
    public static Class classForName(String className) throws ClassNotFoundException
    {
        // Class.forName(className);
        return Thread.currentThread().getContextClassLoader().loadClass(className);
    }

    /**
     * Calling methods using reflection is useful for graceful fallback - this
     * is a helper method to make this easy
     * @param object The object to use as 'this'
     * @param method The method to call, can be null in which case null is returned
     * @param params The parameters to pass to the reflection call
     * @return The results of calling method.invoke() or null
     * @throws IllegalStateException If anything goes wrong
     */
    public static Object invoke(Object object, Method method, Object[] params) throws IllegalStateException
    {
        Object reply = null;
        if (method != null)
        {
            try
            {
                reply = method.invoke(object, params);
            }
            catch (InvocationTargetException ex)
            {
                throw new IllegalStateException("InvocationTargetException calling " + method.getName() + ": " + ex.getTargetException().toString());
            }
            catch (Exception ex)
            {
                throw new IllegalStateException("Reflection error calling " + method.getName() + ": " + ex.toString());
            }
        }

        return reply;
    }

    /**
     * Utility to essentially do Class forName with the assumption that the
     * environment expects failures for missing jar files and can carry on if
     * this process fails.
     * @param name The name for debugging purposes
     * @param className The class to create
     * @param impl The implementation class - what should className do?
     * @return The class if it is safe or null otherwise.
     */
    public static Class classForName(String name, String className, Class impl)
    {
        Class clazz;

        try
        {
            clazz = classForName(className);
        }
        catch (ClassNotFoundException ex)
        {
            // We expect this sometimes, hence debug
            log.debug("Skipping '" + name + "' due to ClassNotFoundException on " + className + ". Cause: " + ex.getMessage());
            return null;
        }
        catch (NoClassDefFoundError ex)
        {
            // We expect this sometimes, hence debug
            log.debug("Skipping '" + name + "' due to NoClassDefFoundError on " + className + ". Cause: " + ex.getMessage());
            return null;
        }
        catch (TransformerFactoryConfigurationError ex)
        {
            // We expect this sometimes, hence debug
            log.debug("Skipping '" + name + "' due to TransformerFactoryConfigurationError on " + className + ". Cause: " + ex.getMessage());
            log.debug("Maybe you need to add xalan.jar to your webserver?");
            return null;
        }

        // Check it is of the right type
        if (!impl.isAssignableFrom(clazz))
        {
            log.error("Class '" + clazz.getName() + "' does not implement '" + impl.getName() + "'.");
            return null;
        }

        // Check we can create it
        try
        {
            clazz.newInstance();
        }
        catch (InstantiationException ex)
        {
            log.error("InstantiationException for '" + name + "' failed:", ex);
            return null;
        }
        catch (IllegalAccessException ex)
        {
            log.error("IllegalAccessException for '" + name + "' failed:", ex);
            return null;
        }
        catch (NoClassDefFoundError ex)
        {
            // We expect this sometimes, hence debug
            log.debug("Skipping '" + name + "' due to NoClassDefFoundError on " + className + ". Cause: " + ex.getMessage());
            return null;
        }
        catch (TransformerFactoryConfigurationError ex)
        {
            // We expect this sometimes, hence debug
            log.debug("Skipping '" + name + "' due to TransformerFactoryConfigurationError on " + className + ". Cause: " + ex.getMessage());
            log.debug("Maybe you need to add xalan.jar to your webserver?");
            return null;
        }
        catch (Exception ex)
        {
            // For some reason we can't catch this?
            if (ex instanceof ClassNotFoundException)
            {
                // We expect this sometimes, hence debug
                log.debug("Skipping '" + name + "' due to ClassNotFoundException on " + className + ". Cause: " + ex.getMessage());
                return null;
            }
            else
            {
                log.error("Failed to load '" + name + "' (" + className + ")", ex);
                return null;
            }
        }

        return clazz;
    }

    /**
     * Utility to essentially do Class forName and newInstance with the
     * assumption that the environment expects failures for missing jar files
     * and can carry on if this process fails.
     * @param name The name for debugging purposes
     * @param className The class to create
     * @param impl The implementation class - what should className do?
     * @return The new instance if it is safe or null otherwise.
     */
    public static Object classNewInstance(String name, String className, Class impl)
    {
        Class clazz;

        try
        {
            clazz = LocalUtil.classForName(className);
        }
        catch (ClassNotFoundException ex)
        {
            // We expect this sometimes, hence debug
            log.debug("Skipping '" + name + "' due to ClassNotFoundException on " + className + ". Cause: " + ex.getMessage());
            return null;
        }
        catch (NoClassDefFoundError ex)
        {
            // We expect this sometimes, hence debug
            log.debug("Skipping '" + name + "' due to NoClassDefFoundError on " + className + ". Cause: " + ex.getMessage());
            return null;
        }
        catch (TransformerFactoryConfigurationError ex)
        {
            // We expect this sometimes, hence debug
            log.debug("Skipping '" + name + "' due to TransformerFactoryConfigurationError on " + className + ". Cause: " + ex.getMessage());
            return null;
        }

        // Check it is of the right type
        if (!impl.isAssignableFrom(clazz))
        {
            log.error("Class '" + clazz.getName() + "' does not implement '" + impl.getName() + "'.");
            return null;
        }

        // Check we can create it
        try
        {
            return clazz.newInstance();
        }
        catch (InstantiationException ex)
        {
            log.error("InstantiationException for '" + name + "' failed:", ex);
            return null;
        }
        catch (IllegalAccessException ex)
        {
            log.error("IllegalAccessException for '" + name + "' failed:", ex);
            return null;
        }
        catch (TransformerFactoryConfigurationError ex)
        {
            log.error("TransformerFactoryConfigurationError for '" + name + "' failed:", ex);
            return null;
        }
        catch (Exception ex)
        {
            log.error("Failed to load creator '" + name + "', classname=" + className + ": ", ex);
            return null;
        }
    }

    /**
     * InputStream closer that can cope if the input stream is null.
     * If anything goes wrong, the errors are logged and ignored.
     * @param in The resource to close
     */
    public static void close(InputStream in)
    {
        if (in == null)
        {
            return;
        }

        try
        {
            in.close();
        }
        catch (IOException ex)
        {
            log.warn(ex.getMessage(), ex);
        }
    }

    /**
     * InputStream closer that can cope if the input stream is null.
     * If anything goes wrong, the errors are logged and ignored.
     * @param in The resource to close
     */
    public static void close(Reader in)
    {
        if (in == null)
        {
            return;
        }

        try
        {
            in.close();
        }
        catch (IOException ex)
        {
            log.warn(ex.getMessage(), ex);
        }
    }

    /**
     * InputStream closer that can cope if the input stream is null.
     * If anything goes wrong, the errors are logged and ignored.
     * @param in The resource to close
     */
    public static void close(RandomAccessFile in)
    {
        if (in == null)
        {
            return;
        }

        try
        {
            in.close();
        }
        catch (IOException ex)
        {
            log.warn(ex.getMessage(), ex);
        }
    }

    /**
     * Return a List of superclasses for the given class.
     * @param clazz the class to look up
     * @return the List of superclasses in order going up from this one
     */
    public static List getAllSuperclasses(Class clazz)
    {
        List classes = new ArrayList();

        Class superclass = clazz.getSuperclass();
        while (superclass != null)
        {
            classes.add(superclass);
            superclass = superclass.getSuperclass();
        }

        return classes;
    }

    /**
     * Return a list of all fields (whatever access status, and on whatever
     * superclass they were defined) that can be found on this class.
     * <p>This is like a union of {@link Class#getDeclaredFields()} which
     * ignores and superclasses, and {@link Class#getFields()} which ignored
     * non-pubic fields
     * @param clazz The class to introspect
     * @return The complete list of fields
     */
    public static Field[] getAllFields(Class clazz)
    {
        List classes = getAllSuperclasses(clazz);
        classes.add(clazz);
        return getAllFields(classes);
    }

    /**
     * As {@link #getAllFields(Class)} but acts on a list of {@link Class}s and
     * uses only {@link Class#getDeclaredFields()}.
     * @param classes The list of classes to reflect on
     * @return The complete list of fields
     */
    private static Field[] getAllFields(List classes)
    {
        Set fields = new HashSet();
        for (Iterator it = classes.iterator(); it.hasNext();)
        {
            Class clazz = (Class) it.next();
            fields.addAll(Arrays.asList(clazz.getDeclaredFields()));
        }

        return (Field[]) fields.toArray(new Field[fields.size()]);
    }

    /**
     * The log stream
     */
    private static final Logger log = Logger.getLogger(LocalUtil.class);

    /**
     * Have we given a warning about URLDecoder.decode() in jdk 1.3
     */
    private static boolean warn13 = false;

    /**
     * Have we tested for the correct URLDecoder.decode()
     */
    private static boolean testedDecoder = false;

    /**
     * Are we using the jdk 1.4 version of URLDecoder.decode()
     */
    private static Method decode14 = null;
}