JSP登录前后改变JSESSIONID

<filter>
<filter-name>filter1</filter-name>
<filter-class>filter.LoginFilter1</filter-class>
</filter>
<filter-mapping>
<filter-name>filter1</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

package filter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class LoginFilter1 implements Filter {//尝试改变JSESSIONID

@Override
public void destroy() {
// TODO Auto-generated method stub
System.out.println("LoginFilter1 destroy");
}

@Override
public void doFilter(ServletRequest arg0, ServletResponse arg1,
FilterChain arg2) throws IOException, ServletException {
// TODO Auto-generated method stub
HttpServletRequest httpRequest = (HttpServletRequest)arg0;
StringBuffer ul = httpRequest.getRequestURL();

if(ul.toString().contains("login!getintoindex.do")){
HttpSession session = httpRequest.getSession(false);

if ( session != null && !session.isNew() ) {//isNew() Returns true if the client does not yet know about the session or if the client chooses not to join the session.
HttpSession sessionOld = session;
User user = (User)sessionOld.getAttribute("user");

sessionOld.invalidate();

session = httpRequest.getSession(true);
session.setAttribute("user", user);

System.out.println("LoginFilter1 doFilter,url: " + httpRequest.getRequestURL()+" , session id: " + httpRequest.getSession().getId());
}
}

if(ul.toString().contains("top!logout.do")){//
HttpSession session = httpRequest.getSession(false);
if ( session != null && !session.isNew() ) {
HttpSession sessionOld = session;
sessionOld.invalidate();
session = httpRequest.getSession(true);

System.out.println("LoginFilter1 doFilter,logout. ");
}

}

arg2.doFilter(arg0, arg1);

}

@Override
public void init(FilterConfig arg0) throws ServletException {
// TODO Auto-generated method stub
System.out.println("LoginFilter1 init");
}

}