public class BaseServlet extends HttpServlet { protected CompanyService companyService; protected DeptService deptService; protected UserService userService; @Override public void init() throws ServletException { companyService = new CompanyServiceImpl(); deptService = new DeptServiceImpl(); userService = new UserServiceImpl(); }创建对象的抽取,init()方法,便于后期进行维护,减少缓存,占用,减少new的次数