问一个servlet 请求转发问题

import java.io.IOException;

import java.io.PrintWriter;



import javax.servlet.RequestDispatcher;

import javax.servlet.ServletContext;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;





public class Test extends HttpServlet {



	

	public void  doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

	   

		//System.out.println("a");

		//return null;

		test(request,response);

	}



	public String test(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{

	    response.setContentType("text/html; charset=gb2312"); 

		ServletContext sc = getServletContext(); 

		RequestDispatcher rd = null; 

		rd=sc.getRequestDispatcher("/index.jsp");

		rd.forward(request,response);

		return null;

	}

	

}

抛异常了

at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:352)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:302)
at Test.test(Test.java:27)
at Test.doGet(Test.java:19)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
------解决方案--------------------
RequestDispatcher rd = request.getRequestDispatcher("/index.jsp"); 
rd.forward(request, response);
试试