// userService.java

public interface userService {

    public void insertUser();

}

// xmlImpl.java

public class xmlImpl implements userService{

    @Override

    public void insertUser() {

        System.out.println("insert a user");

    }

}

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation="http://www.springframework.org/schema/beans

        http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="userService" class="service.xmlImpl"></bean>

</beans>

public class userView extends HttpServlet {

    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        // 获取Spring容器context

        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");

        // 方式1，靠id拿bean

        userService service = (userService) context.getBean("userService");

        service.insertUser();

        // 方式2，靠class拿bean

        userService service2 = context.getBean(userService.class);

        service2.insertUser();

        response.getWriter().println("123");

    }

}