那位可有LoginAction的例题？Struts框架

public class view extends baseview(){
    public String username=null;
    public String password=null
   public view{
super()
  }; public String getusername(){
this.username;
}
 
 public void setusername(String username){
this.username=username;
}public String getpassword(){
this.password;
}
 
 public void setpassword(String username){
this.password=username;
} 
    public String getView(){
this.View;
}
 
 public void setView(String View){
this.View=View;
}}
public ActionForward execute(ActionMapping mapping,
                               ActionForm form,
                               HttpServletRequest request,
                               HttpServletResponse response) {
  //  HttpSession session = null;
    String user = null;
    String target = new String("success");
          String username = ((LoginForm)form).getUsername();
          String password = ((LoginForm)form).getPassword();
    user = checkUser(username, password);
             view view=null;
             HttpSession session = getSession(false);
    if ( session == null ) {
      session.invalidate;     }
    else {
                   view view=new view();
                   view.setView(user);
    session=request.getSession(true);
     session.setAttribute("view",view)
      
    }
          return (mapping.findForward(target));
}
}
在这段代码中我想用session限制用户必须经过login.jsp才能登录到index.jsp，请问这样行吗，为什么？怎么做呢？