HttpSession session=request.getSession();
这个错误
HttpSession cannot be resolved to a type
怎么解决 我在MYECLIPSE下编写的

mport java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
还少什么包？
[ 本帖最后由 丁立刚 于 2011-08-04  12:06 编辑 ]

HttpSession session = request.getSession();

这里的
request 必须是
javax.servlet.http.HttpServletRequest;

session必须是：
javax.servlet.http.HttpSession;

如果说你现在只有 javax.servlet.ServletRequest对象的话

你要转换一下
public void doFilter(ServletRequest req, ServletResponse res,
   FilterChain chain) throws IOException, ServletException {
    HttpServletRequest request = (HttpServletRequest) req;
    HttpSession session=request.getSession();
}