用户注册功能：首先在inputCustomer.jsp中输入客户信息（包括客户名、email和电话），然后跳转至CustomerServlet进行处理，最后将请求转发到displayCustomer.jsp页面显示客户输入的信息。其中在CustomerServlet中将获取的客户信息创建JavaBean类为Customer的实例，并通过作用域对象共享(User registration function: first, input customer information in inputCustomer.jsp (including customer name, email and phone), then jump to CustomerServlet for processing, and finally forward the request to the displayCustomer.jsp page to display the information input by the customer. In the CustomerServlet, the customer information obtained in the JavaBean is created as an instance of Customer and shared by scoped objects.)