自定义Scope实现每个线程持有一个bean实例

/**
 * 自定义Bean的Scope
 * target: 每个线程获取到的Bean实例都是同一个
 *
 * @author ft
 * @date 2021/1/28
 */
@Component(ThreadScope.SCOPE)
public class ThreadScope implements Scope, BeanFactoryPostProcessor {
    /**
     * 线程本地变量持有当前线程获取到的Bean实例
     */
    private static final ThreadLocal<Object> THREAD_LOCAL_BEAN = new ThreadLocal<>();
    /**
     * 自定义的Scope的名称
     */
    public static final String SCOPE = "threadLocal";
    @Override
    public Object get(String name, ObjectFactory<?> objectFactory) {
        Object o = THREAD_LOCAL_BEAN.get();
        if (o == null) {
            THREAD_LOCAL_BEAN.set(objectFactory.getObject());
        }
        return THREAD_LOCAL_BEAN.get();
    }
    @Override
    public Object remove(String name) {
        Object o = THREAD_LOCAL_BEAN.get();
        THREAD_LOCAL_BEAN.remove();
        return o;
    }
    @Override
    public void registerDestructionCallback(String name, Runnable callback) {
    }
    @Override
    public Object resolveContextualObject(String key) {
        return null;
    }
    @Override
    public String getConversationId() {
        return null;
    }
    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        // 将自定义的Scope注册到容器中
        beanFactory.registerScope(ThreadScope.SCOPE, this);
    }
}

/**
 * Scope为每个线程持有一个对象
 *
 * @author ft
 * @date 2021/1/28
 */
@Scope(ThreadScope.SCOPE)
@Component
@Slf4j
public class TestThreadBean {
    /**
     * 构造方法，当进行了实例构建可以看到日志
     */
    public TestThreadBean() {
        log.info(".");
    }
    public void sayThing() {
        log.info("-");
    }
}

/**
 * @author ft
 * @date 2021/1/28
 */
@Slf4j
@Component
public class ThreadScopeTest implements ApplicationRunner {
    @Autowired
    private ApplicationContext applicationContext;
    @Override
    public void run(ApplicationArguments args) throws Exception {
        // 开启10个线程
        for (int i = 0; i < 10; i++) {
            new Thread(() -> {
                // 从容器中获取TestThreadBean实例
                TestThreadBean bean1 = applicationContext.getBean(TestThreadBean.class);
                log.info("第一次获取:{}", bean1);
                // 同一个线程第二次从容器中获取TestThreadBean实例
                TestThreadBean bean2 = applicationContext.getBean(TestThreadBean.class);
                log.info("第二次获取:{}", bean2);
            }, "scope-test-" + i).start();
        }
    }
}