java 类处理工具

public class ClassUtils {

    private static final Logger LOGGER  = LoggerFactory.getLogger(ClassUtils.class);

    /**
     * 返回某个父类底下所有的实现类
     */public static List<Class> getSubClassesByParentClass(Class parentClass) {

        List<Class> returnClassList = new ArrayList<Class>();

        String packageName = parentClass.getPackage().getName();
        try {
            List<Class> allClass = getClassesByPackageName(packageName);
            for (int i = 0; i < allClass.size(); i++) {
                if (parentClass.isAssignableFrom(allClass.get(i))) {
                    if (!parentClass.equals(allClass.get(i))) {
                        returnClassList.add(allClass.get(i));
                    }
                }
            }
        } catch (Exception e) {
            LOGGER.error(e.getMessage(), e);
        }
        return returnClassList;
    }

    /**
     * 从一个包中查找出所有类,在jar包中不能查找
     *
     * @param packageName
     * @return
     * @throws IOException
     * @throws ClassNotFoundException
     */
    public static List<Class> getClassesByPackageName(String packageName)
            throws IOException, ClassNotFoundException {
        ClassLoader classLoader = Thread.currentThread()
                .getContextClassLoader();
        String path = packageName.replace('.', '/');
        Enumeration<URL> resources = classLoader.getResources(path);
        List<File> dirs = new ArrayList<File>();
        while (resources.hasMoreElements()) {
            URL resource = resources.nextElement();
            dirs.add(new File(resource.getFile()));
        }
        ArrayList<Class> classes = new ArrayList<Class>();
        for (File directory : dirs) {
            classes.addAll(findClasses(directory, packageName));
        }
        return classes;
    }

    /**
     *
     * @param directory
     * @param packageName
     * @return
     * @throws ClassNotFoundException
     */
    public static List<Class> findClasses(File directory, String packageName)
            throws ClassNotFoundException {
        List<Class> classes = new ArrayList<Class>();
        if (!directory.exists()) {
            return classes;
        }
        File[] files = directory.listFiles();
        for (File file : files) {
            if (file.isDirectory()) {
                assert !file.getName().contains(".");
                classes.addAll(findClasses(file, packageName + '.'
                        + file.getName()));
            } else if (file.getName().endsWith(".class")) {
                classes.add(Class.forName(packageName
                        + "."
                        + file.getName().substring(0,
                                file.getName().length() - 6)));
            }
        }
        return classes;
    }

    /**
     * 对Map类型数据按Key排序
     *
     * @param map
     */public static List sort(Map map) {
        List list = new ArrayList(map.keySet());
        Collections.sort(list, new Comparator() {
            public int compare(Object a, Object b) {
                return a.toString().toLowerCase().compareTo(
                        b.toString().toLowerCase());
            }
        });
        return list;
    }
}