给定一个接口返回这个接口所有实现类

package com.dobn.bdgcgl.test;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;

public class ClassUtils {
	
	/**
	 * 
	 * @author ym
	 * @CreateTime 2013-2-28上午09:51:15
	 * 描述：给一个接口，返回这个接口的所有实现类
	 */
	public static List<Class> getAllClassByInterface(Class c){
		//返回结果
		List<Class> returnClassList = new ArrayList<Class>();
		//如果不是一个接口则不做处理
		if (c.isInterface()) {
			//获取当前包名
			String packageName = c.getPackage().getName();
			try {
				//获取当前包下以及子包下的所有类
				List<Class> allClass = getClasses(packageName);
				//判断是否是同一个接口
				for (int i = 0; i < allClass.size(); i++) {
					if (c.isAssignableFrom(allClass.get(i))) {
						if (!c.equals(allClass.get(i))) {
							returnClassList.add(allClass.get(i));
						}
					}
				}
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		return returnClassList;
	}
	
	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;
	}

}