自定义 Bean 作用域

傷城~ 2022-11-07 11:54 196阅读 0赞

Spring 实现自定义的 bean 作用域

*  实现 Scope 接口
 *  调用 AbstractBeanFactory\#registerScope 方法
 *  bean 配置的地方指定作用域，如 <bean scope=""> 或 @Scope("")

以下实现一个线程级别的 bean 的作用域

先看 Scope 接口的实现

/**
     * 线程级别 scope
     * 
     * @author ConstXiong
     */
    public class ThreadLocalScope implements Scope {
    	
    	public static final String SCOPE_NAME = "thread-local";
    	
    	private static final ThreadLocal<Map<String, Object>> THREAD_LOCAL = new ThreadLocal<Map<String, Object>>() {
    		@Override
    		protected Map<String, Object> initialValue() {
    	        return new HashMap<>();
    	    }
    	}; 
    
    	@Override
    	public Object get(String name, ObjectFactory<?> objectFactory) {
    		Map<String, Object> map = THREAD_LOCAL.get();
    		Object object = map.get(name);
    		if (object == null) {
    			object = objectFactory.getObject();
    			map.put(name, object);
    		}
    		return object;
    	}
    
    	@Override
    	public Object remove(String name) {
    		return THREAD_LOCAL.get().remove(name);
    	}
    
    	@Override
    	public void registerDestructionCallback(String name, Runnable callback) {
    	}
    
    	@Override
    	public Object resolveContextualObject(String key) {
    		return THREAD_LOCAL.get().remove(key);
    	}
    
    	@Override
    	public String getConversationId() {
    		return String.valueOf(Thread.currentThread().getId());
    	}
    
    }

使用 ApplicationContextAware 接口获取 ApplicationContext，在其 BeanFactory 中注册 ThreadLocalScope

/**
     * 注册 ThreadLocalScope
     * 
     * @author ConstXiong
     */
    @Component
    public class ScopeRegister implements ApplicationContextAware {
    
    	@Override
    	public void setApplicationContext(ApplicationContext applicationContext)
    			throws BeansException {
    		WebApplicationContext context = (WebApplicationContext)applicationContext;
    		DefaultListableBeanFactory beanFactory = ((DefaultListableBeanFactory)context.getAutowireCapableBeanFactory());
    		beanFactory.registerScope(ThreadLocalScope.SCOPE_NAME, new ThreadLocalScope());
    	}
    
    }

bean 配置与 controller

/**
     * controller
     * 
     * @author ConstXiong
     */
    @Controller
    public class IndexController {
    	
    	@Autowired
    	private ApplicationContext context;
    	
    	@RequestMapping("thread")
    	@ResponseBody
    	public String thread() {
    		User user = context.getBean("user", User.class);
    		return String.format("thread:%s, user:%s", Thread.currentThread().getId(), user);
    	}
    	
    	@Bean
    	@Scope(ThreadLocalScope.SCOPE_NAME)
    	private static User user() {
    		return new User();
    	}
    	
    }

这样在页面请求 http://localhost:8080/thread，线程 id 不同，bean id 也不同

[完整代码：023-spring-bean-custom-scope][023-spring-bean-custom-scope]

--------------------

### 【Java学习资源】整理推荐 ###

*  [自定义 Bean 作用域][Bean]
 *  [Bean 的作用域][Bean 1]
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 *  [Spring 依赖注入与依赖查找来源的区别][Spring]
 *  [Spring 依赖注入的处理过程与 DependencyDescriptor 的说明][Spring _ DependencyDescriptor]
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 *  [Spring Bean 生命周期内的 Exception 复现][Spring Bean _ Exception]
 *  [Spring 内建 Bean][Spring _ Bean]
 *  [Spring Bean 的别名][Spring Bean]
 *  [Spring Bean 未指定名称的命名规则][Spring Bean 1]
 *  [Bean 何时被 GC][Bean _ GC]
 *  [Spring Bean 延迟加载][Spring Bean 2]
 *  [ObjectFactory 与 BeanFactory 的区别][ObjectFactory _ BeanFactory]
 *  [Bean 销毁的方式与顺序][Bean 2]
 *  [Bean 初始化的方式与顺序][Bean 3]
 *  [Bean 的实例化方式][Bean 4]
 *  [Bean的注册方式][Bean 5]
 *  [什么是 BeanDefinition？][BeanDefinition]
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 *  [BeanFactory 与 FactoryBean 的区别][BeanFactory _ FactoryBean]
 *  [BeanFactory 与 ApplicationContext 的区别][BeanFactory _ ApplicationContext]
 *  [Spring IoC 依赖注入的实现方式][Spring IoC 1]
 *  [Spring IoC 依赖注入(支持哪些数据类型？)][Spring IoC 2]
 *  [Spring bean 依赖查找][Spring bean]
 *  [Spring-IoC][]
 *  [Spring 的核心特性][Spring 1]

--------------------

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*  [基础与语法][Link 1]
 *  [集合][Link 2]
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 *  [Web][]
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 *  [设计模式][Link 6]
 *  [框架][Link 7]
 *  [算法与数据结构][Link 8]
 *  [异常][Link 9]
 *  [文件解析与生成][Link 10]
 *  [Linux][]
 *  [MySQL][]
 *  [Oracle][]
 *  [Redis][]
 *  [Dubbo][]

[023-spring-bean-custom-scope]: https://github.com/ConstXiong/toy/tree/master/spring-study/023-spring-bean-custom-scope
[Bean]: https://www.javanav.com/val/3fdc7ac3bd034a5ab7040e23f37153fa.html
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[Spring IoC]: https://www.javanav.com/val/d382c8380fc2480788a35a7e671b5e9b.html
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[Spring IoC 1]: https://www.javanav.com/val/a835e6c709ea439ebb21a80f1bf77926.html
[Spring IoC 2]: https://www.javanav.com/val/e377beac22644c2c85308079b239a0fd.html
[Spring bean]: https://www.javanav.com/val/7f8c2e1f24db46e79bc4b9b04f9ad715.html
[Spring-IoC]: https://www.javanav.com/val/a412668efda74412a13f6df9a6d2c714.html
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[MySQL]: https://www.javanav.com/interview/d311e78502a845f1a4bb307bd6aec2b3.html
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