Cannot forward after response has been committed 问题求解

[denghan19]

package com.gem.comm2;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.gem.comm.zhucebiao;
import com.gem.comm.zhuceDao;
import com.gem.comm.zhuceDaoImpl;

public class zhuceServlet3 extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("GBK");
response.setCharacterEncoding("GBK");
String name = request.getParameter("zhanghao");
String password = request.getParameter("mima");
//获取全局参数
ServletContext sc = this.getServletContext();
String scName = sc.getInitParameter("name");

System.out.println("ServletContext:"+scName);
//获取局部参数
ServletConfig scfig = this.getServletConfig();
String scfigName = scfig.getInitParameter("commParam");
System.out.println("ServletConfig:"+scfigName);

zhuceDao zhuDao = new zhuceDaoImpl();
zhucebiao zhuce = zhuDao.comm(name, password);

if(zhuce == null){
// response.sendRedirect("http://www.sohu.com");
response.sendRedirect("comm2.html");

//表明前台请求处理完成后，将要跳转到哪个页面
RequestDispatcher rd = request.getRequestDispatcher("comm2.html");
// //进行跳转
rd.forward(request, response);
}else{
request.getRequestDispatcher("welcome").forward(request, response);
}

}

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

this.doGet(request, response);
}

}
这是我代码 老是跳转不过去
报错是
java.lang.IllegalStateException: Cannot forward after response has been committed
com.gem.servlet.day2.Day2LoginServlet.doGet(Day2LoginServlet.java:45)
javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)