java - 设计模式-无DI框架的webapp

Question

我需要在没有依赖注入(inject)框架的情况下实现 servlet 3.0 webapp。哪种解决方案是最佳实践？ (在性能/内存使用和可扩展性方面)

1)DAO和服务层的静态方法

@WebServlet("/welcome")
public class MyController extends HttpServlet {

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

        MyService.doSomething(/*args*/);
    }
}

public class MyService {

    public static void doSomething(/*args*/) {
        MyDAO.crud(/*args*/);
    }
}

public class MyDAO {

    public static void crud(/*args*/) {
        //...
    }
}

2)接口(interface)

@WebServlet("/welcome")
public class MyController extends HttpServlet {

    private MyService myService;

    public MyController() {
        super();
        if (myService != null) {
            myService = new MyServiceImpl();
        }

    }

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

        myService.doSomething(/*args*/);
    }
}

public interface MyService {

    void doSomething(/*args*/);
}

public class MyServiceImpl implements MyService {

    private MyDAO myDAO;

    public MyServiceImpl() {
        if (myService != null) {
            myDAO = new MyDAOImpl();
        }
    }

    @Override
    public void doSomething(/*args*/) {
        myDAO.crud(/*args*/);
    }
}

public interface MyDAO {

    void crud(/*args*/);
}

public class MyDAOImpl implements MyDAO {

    @Override
    public void crud(/*args*/) {
        //...
    }
}

3)其他的东西......

谢谢。

Answer 1

最好将应用程序中的MyService和MyDAO设置为无状态。您可以将它们都设置为单例(这是所有spring注入(inject)的bean的默认范围) ，然后在您的 Controller 中使用它。由于其无状态，因此不存在并发问题。