从java设计模式之禅看到的很好的ClassUtils类

import java.io.File;import java.io.IOException;import java.net.URL;import java.util.ArrayList;import java.util.Enumeration;import java.util.List;@SuppressWarnings("all")public class ClassUtils {// 给一个接口，返回这个接口的所有实现类public static List<Class> getAllClassByInterface(Class c) {List<Class> returnClassList = new ArrayList<Class>(); // 返回结果// 如果不是一个接口，则不做处理if (c.isInterface()) {String packageName = c.getPackage().getName(); // 获得当前的包名try {List<Class> allClass = getClasses(packageName); // 获得当前包下以及子包下的所有类// 判断是否是同一个接口for (int i = 0; i < allClass.size(); i++) {if (c.isAssignableFrom(allClass.get(i))) { // 判断是不是一个接口if (!c.equals(allClass.get(i))) { // 本身不加进去returnClassList.add(allClass.get(i));}}}} catch (ClassNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}return returnClassList;}// 从一个包中查找出所有的类，在jar包中不能查找private static List<Class> getClasses(String packageName)throws ClassNotFoundException, IOException {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;}private 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;}}