spring中所有使用到设计模式的地方有哪些，并给出代码示例

Spring中使用到的设计模式有：

1. 单例模式：Spring默认所有的bean都是单例的，保证了在整个应用中只有一个实例。

2. 工厂模式：Spring使用工厂模式创建和管理bean，可以通过BeanFactory和ApplicationContext获取bean。

3. 代理模式：Spring使用代理模式实现AOP，通过代理对象来增强目标对象的功能。

4. 模板方法模式：Spring中的JdbcTemplate、HibernateTemplate等都是基于模板方法模式实现的。

5. 观察者模式：Spring中的事件驱动模型就是基于观察者模式实现的，通过ApplicationContext发布事件，然后监听器接收事件并处理。

6. 适配器模式：Spring中的适配器模式主要应用在MVC框架中，通过适配器来将不同的请求适配到不同的处理器上。

代码示例：

1. 单例模式

@Component
public class SingletonExample {
    private static SingletonExample instance;

    private SingletonExample() {}

    public static SingletonExample getInstance() {
        if (instance == null) {
            instance = new SingletonExample();
        }
        return instance;
    }
}

2. 工厂模式

public interface MyBean {
    void sayHello();
}

@Component("myBean1")
public class MyBeanImpl1 implements MyBean {
    @Override
    public void sayHello() {
        System.out.println("Hello from MyBeanImpl1");
    }
}

@Component("myBean2")
public class MyBeanImpl2 implements MyBean {
    @Override
    public void sayHello() {
        System.out.println("Hello from MyBeanImpl2");
    }
}

public class MyBeanFactory {
    public static MyBean getMyBean(String beanName) {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        return (MyBean) context.getBean(beanName);
    }
}

3. 代理模式

@Component
public class MyServiceProxy implements MyService {
    @Autowired
    private MyService myService;

    @Override
    public void doSomething() {
        System.out.println("Before doSomething...");
        myService.doSomething();
        System.out.println("After doSomething...");
    }
}

@Component
public class MyServiceImpl implements MyService {
    @Override
    public void doSomething() {
        System.out.println("doSomething...");
    }
}

4. 模板方法模式

@Component
public class MyJdbcTemplate extends JdbcTemplate {
    @Autowired
    public MyJdbcTemplate(DataSource dataSource) {
        super(dataSource);
    }

    public List<Map<String, Object>> query(String sql) {
        return super.queryForList(sql);
    }
}

5. 观察者模式

public class MyEvent extends ApplicationEvent {
    public MyEvent(Object source) {
        super(source);
    }
}

@Component
public class MyEventListener implements ApplicationListener<MyEvent> {
    @Override
    public void onApplicationEvent(MyEvent event) {
        System.out.println("Received MyEvent: " + event.getSource());
    }
}

@Component
public class MyEventPublisher {
    @Autowired
    private ApplicationContext context;

    public void publishEvent() {
        context.publishEvent(new MyEvent(this));
    }
}

6. 适配器模式

public interface MyController {
    void handleRequest(HttpServletRequest request, HttpServletResponse response);
}

public class MyController1 {
    public void handleRequest1(HttpServletRequest request, HttpServletResponse response) {
        // handle request
    }
}

public class MyController2 {
    public void handleRequest2(HttpServletRequest request, HttpServletResponse response) {
        // handle request
    }
}

public class MyHandlerAdapter implements HandlerAdapter {
    @Override
    public boolean supports(Object handler) {
        return (handler instanceof MyController);
    }

    @Override
    public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        MyController controller = (MyController) handler;
        controller.handleRequest(request, response);
        return null;
    }

    @Override
    public long getLastModified(HttpServletRequest request, Object handler) {
        return -1;
    }
}