java.lang.NoClassDefFoundError如何解决这个错误

Question

当我提交注册表单注册servlet运行但是当我创建了休眠会话工厂的对象它给了我一个异常。“javax.servlet.ServletException：Servlet执行抛出一个例外 org.apache.tomcat.websocket.server.WsFilter.doFilter（WsFilter.java:52）“。请帮我看看这个例外。

package login; 

import java.io.IOException; 
import javax.servlet.ServletException; 
import javax.servlet.annotation.WebServlet; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 

import org.hibernate.Session; 
import org.hibernate.SessionFactory; 
import org.hibernate.cfg.Configuration; 

import org.hibernate.SessionFactory; 

@WebServlet("/Registration") 
public class Registration extends HttpServlet { 
    private static final long serialVersionUID = 1L; 

public Registration() { 
    super(); 
    // TODO Auto-generated constructor stub 
} 


protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
    // TODO Auto-generated method stub 
    String username = request.getParameter("username"); 
    String password = request.getParameter("password"); 
    String name = request.getParameter("name"); 

    User u = new User(); 
    u.setUsername(username); 
    u.setPassword(password); 
    u.setName(name); 

    SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory(); 

} 

Answer 1

添加最新hibernate.jar在类路径