如何用URLClassLoader来加载一个指定目录下的class类 ServletWeb

直接插入我的代码：

public class ServletProcessor1 {

	public void process(Request request, Response response) {
		// TODO Auto-generated method stub
		String uri = request.getUri();
		System.out.println(uri);
		String servletName = uri.substring(uri.lastIndexOf("/")+1);
		URLClassLoader loader = null;
		try{
			URL[] urls = new URL[1];
			URLStreamHandler streamHandler = null;
			File classPath = new File(Constants.WEB_ROOT);
			
			String repository = (new URL("file",null,classPath.getCanonicalPath()+File.separator)).toString();
			urls[0] = new URL(null,repository,streamHandler);
			loader = new URLClassLoader(urls);
		}catch(IOException e){
			e.printStackTrace();
		}
		Class myClass = null;
		try{
			myClass = loader.loadClass(servletName);
		}catch(ClassNotFoundException e){
			System.out.println(e.toString());
		}
		Servlet servlet = null;
		try{
			servlet = (Servlet)myClass.newInstance();
			servlet.service((ServletRequest)request, (ServletResponse)response);
		}catch(Exception e){
			System.out.println(e.toString());			
		}
	}
}

 运行时，总发现 myClass = loader.loadClass(servletName); 报错，

"servletName" 是有WebRoot/WEb-INF/CLASS文件下是有的,

不过在com/servlet_/test/包下面.

 

请高手赐教，急呀！