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概述

通过Spring管理的类,默认是单例模式,但是如果有的类需要使用独立的属性,则需要配置为多例模式的. 但是多例模式不仅仅只是加一个声明,使用@Autowired进行注入,可能并不会是你想要的结果.因为多例模式的类是需要单独调用的. 不搞清楚原理直接测试： 需要多例的类上加上注解@Scope(“prototype”)

@Component@Scope("prototype")public class ExampleService{	public void test(){		System.out.println("test,current bean is" + this);	}	}

引用直接使用@Autowired

@Controllerpublic class ExampleService{	@Autowired	private ExampleService exampleService;		@RequestMapping("test")	public void test(){		exampleService.test();	}	}

结果: 每个request过来的时候,exampleService实例均为同一个实例.

解决办法：

第一种：不使用@Autowired

@Controllerpublic class ExampleService{	@Autowired	private org.springframework.beans.factory.BeanFactory beanFactory;		@RequestMapping("test")	public void test(){		ExampleService exampleService = beanFactory.getBean(ExampleService.class);		exampleService.test();	}}

第二种：使用bean工厂

@Autowired private ApplicationContext context; @Bean    public WebSocketHandler websocketBHandler() {        PerConnectionWebSocketHandler perConnectionHandler = new PerConnectionWebSocketHandler(WebSocketBHandler.class);        perConnectionHandler.setBeanFactory(context.getAutowireCapableBeanFactory());        //设置bean工厂，否则bean工厂WebSocketBHandler将不会自动连接        return perConnectionHandler;    }

然后使用ApplicationContext进行代理bean工厂

注入@Autowiredprivate ApplicationContext context;使用this.Bservice = context.getBean(BService.class, this);

官方文档说明

4.5.3 Singleton beans with prototype-bean dependencies When you use singleton-scoped beans with dependencies on prototype beans, be aware that dependencies are resolved at instantiation time. Thus if you dependency-inject a prototype-scoped bean into a singleton-scoped bean, a new prototype bean is instantiated and then dependency-injected into the singleton bean. The prototype instance is the sole instance that is ever supplied to the singleton-scoped bean. However, suppose you want the singleton-scoped bean to acquire a new instance of the prototype-scoped bean repeatedly at runtime. You cannot dependency-inject a prototype-scoped bean into your singleton bean, because that injection occurs only once, when the Spring container is instantiating the singleton bean and resolving and injecting its dependencies. If you need a new instance of a prototype bean at runtime more than once, see Section 4.4.6, “Method injection” 《参考：

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