如何获取HttpServletRequest 对象？

[changyulinjava]

public class MethodInterceptorTest implements MethodInterceptor{ //拦截器拦截业务层

public Object invoke(MethodInvocation methodInvocation) throws Throwable {

//请问我如何在这里获得HttpServletRequest 对象？

}
}

注：这中方法试过了，不能获取。
HttpServletRequest request = null;
ActionMapping mapping = null;
for (int i = 0; i < arguments.length; i++) {
if (arguments[i] instanceof HttpServletRequest) {
request = (HttpServletRequest) arguments[i];
}
if (arguments[i] instanceof ActionMapping) {
mapping = (ActionMapping) arguments[i];
}
}

[changyulinjava]

大家帮忙看看啊，谢谢了。

[kkvoo]

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;