自定义ClassLoader，让spring加载外部的配置文件和类

package net.kyfxbl.test;

public class User {

	private String name;

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public void sayName() {
		System.out.println(getName());
	}

}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans 
	http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

	<bean id="myUser" class="net.kyfxbl.test.User">
		<property name="name" value="kyfxbl" />
	</bean>
	
</beans>

public class Main {

	public static void main(String[] args) {

		try {

			ApplicationContext applicationContext = new ClassPathXmlApplicationContext(
					"spring-config.xml");

			DefaultListableBeanFactory beanFactory = (DefaultListableBeanFactory) applicationContext
					.getAutowireCapableBeanFactory();

			String configurationFilePath = "jar:file:/C:/hehe.jar!/spring-plugin.xml";

			URL url = new URL(configurationFilePath);

			UrlResource urlResource = new UrlResource(url);

			XmlBeanFactory xbf = new XmlBeanFactory(urlResource);

			String[] beanIds = xbf.getBeanDefinitionNames();

			for (String beanId : beanIds) {
				BeanDefinition bd = xbf.getMergedBeanDefinition(beanId);
				beanFactory.registerBeanDefinition(beanId, bd);
			}

			// 以下这行设置BeanFactory的ClassLoader，以加载外部类
			setBeanClassLoader(beanFactory);

			Object pluginBean = applicationContext.getBean("myUser");

			tryInvoke(pluginBean);

		} catch (Exception exc) {
			exc.printStackTrace();
		}

	}

	private static void setBeanClassLoader(
			DefaultListableBeanFactory beanFactory)
			throws MalformedURLException {
		String jarFilePath = "c://hehe.jar";
		URL jarUrl = new File(jarFilePath).toURI().toURL();
		URL[] urls = new URL[] { jarUrl };
		URLClassLoader cl = new URLClassLoader(urls);
		beanFactory.setBeanClassLoader(cl);
	}

	private static void tryInvoke(Object bean) throws SecurityException,
			NoSuchMethodException, IllegalArgumentException,
			IllegalAccessException, InvocationTargetException {

		Class<?> paramTypes[] = new Class[0];
		Method method = bean.getClass()
				.getDeclaredMethod("sayName", paramTypes);
		Object paramValues[] = new Object[0];
		method.invoke(bean, paramValues);

	}

}

setBeanClassLoader(beanFactory);

// 打印ClassLoader看看
			printClassLoader(beanFactory);

			// 以下这行设置BeanFactory的ClassLoader，以加载外部类
			setBeanClassLoader(beanFactory);

private static void printClassLoader(DefaultListableBeanFactory beanFactory) {
		ClassLoader defaultBeanClassLoader = beanFactory.getBeanClassLoader();
		System.out.println(defaultBeanClassLoader);

		ClassLoader currentClassLoader = Main.class.getClassLoader();
		System.out.println(currentClassLoader);
	}

	URL url = new URL("jar:file:G:/maven/repo/com/google/code/gson/gson/2.2.1/gson-2.2.1.jar!/");
		@SuppressWarnings("resource")
		URLClassLoader uc = new URLClassLoader(new URL[]{url});
		Class<?> cls = uc.loadClass("com.google.gson.Gson");
		Object obj = cls.newInstance();
        logger.info(obj);