java.lang.reflect.Method （java反射机制）

公司Vac方法过滤器使用到反射机制，读取xml配置文件过滤用户访问的方法名是否合法。
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest httpRequest = (HttpServletRequest) request;
        @SuppressWarnings("unchecked")
        Map<Object, Object> requestData = (Map<Object, Object>) httpRequest.getAttribute("requestData");
        String methodName = (String) requestData.get(METHOD);
        //获得bean的配置
        String beanName = mapProtocol.get(methodName).get(BEAN);
        // 去除.符号
        methodName = getMethod(methodName);
        //从spring context中获得bean
        Object instance = getContext(filterConfig).getBean(beanName);
        Class<? extends Object> clazz = instance.getClass();
        Object resultContent = null;
        try {
            Method method = clazz
                    .getDeclaredMethod(methodName, getParamTypes());
            Map params = removeSysParams(requestData);
            resultContent = method.invoke(instance, params);
        } catch (InvocationTargetException e) {
            if (e.getTargetExce