我创建了一个注解，用于创建填充了来自环境的值的 ThreadPoolTask​​Executors。但是，当我 Autowiring bean 时，它会给我一个代理，并且调用代理上的方法会给出错误的值。

如果我手动访问目标类，那么我会得到正确的值。

Executor exec = (Executor) ((Advised) executor).getTargetSource().getTarget();
ThreadPoolTaskExecutor taskExec = (ThreadPoolTaskExecutor) exec;

对于为什么要获取代理 bean，我已经摸不着头脑了一段时间，但似乎无法弄清楚。

我正在使用注释导入我的注册器类，该类实现了 ImportBeanDefinitionRegistrar 以注册 bean。注册商代码如下:

public class ExecutorEnumerationRegistrar implements ImportBeanDefinitionRegistrar, EnvironmentAware {

    public static final String CORE_POOL_SIZE = "corePoolSize";
    public static final String MAX_POOL_SIZE = "maxPoolSize";
    public static final String QUEUE_CAPACITY = "queueCapacity";
    public static final String THREAD_NAME_PREFIX = "threadNamePrefix";
    private static final String REJECTED_EXECUTION_HANDLER = "rejectedExecutionHandler";
    private static final String NAMES = "names";
    private static final String REJECTED_HANDLER = "rejectedHandler";
    private Environment env;

    @Override
    public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
        Map<String, Object> attrs = importingClassMetadata.getAnnotationAttributes(ThreadPoolTaskExecutorCreator.class.getName(), true);
        final String[] beanNames = (String[]) attrs.get(NAMES);
        final String[] policyClass = (String[]) attrs.get(REJECTED_HANDLER);
        for (int x = 0; x < beanNames.length; x++) {
            createAndRegisterBean(beanNames[x], policyClass[x], registry);
        }
    }

    private void createAndRegisterBean(String name, String policyClass, BeanDefinitionRegistry registry) {
        GenericBeanDefinition bd = new GenericBeanDefinition();
        bd.setBeanClass(ThreadPoolTaskExecutor.class);
        bd.setAutowireCandidate(true);
        bd.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
        MutablePropertyValues mpv = bd.getPropertyValues();
        populateProperties(mpv, name, policyClass);
        registry.registerBeanDefinition(name, bd);
    }

    private void populateProperties(MutablePropertyValues mpv, String name, String policyClass) {
        mpv.add(CORE_POOL_SIZE, Integer.valueOf(env.getProperty(name + "." + CORE_POOL_SIZE)));
        mpv.add(MAX_POOL_SIZE, Integer.valueOf(env.getProperty(name + "." + MAX_POOL_SIZE)));
        mpv.add(QUEUE_CAPACITY, Integer.valueOf(env.getProperty(name + "." + QUEUE_CAPACITY)));
        try {
            mpv.add(REJECTED_EXECUTION_HANDLER, Class.forName(policyClass).newInstance());
        } catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) {
            e.printStackTrace();
        }
        mpv.add(THREAD_NAME_PREFIX, name + "-");
    }

    @Override
    public void setEnvironment(Environment environment) {
        env = environment;
    }

}

导入注册器的注解:

@Retention(RetentionPolicy.RUNTIME)  
@Target(ElementType.TYPE) 
@Documented 
@Import(ExecutorEnumerationRegistrar.class) 
public @interface ThreadPoolTaskExecutorCreator{ 

    String[] names(); 

    String[] rejectedHandler() default ThreadPoolPolicyHandlers.CALLER_RUNS_POLICY; 

} 

我已经用下面的代码进行了测试: Spring 启动类:

@EnableDiscoveryClient
@ComponentScan("my.test.classes")
@ThreadPoolTaskExecutorCreator(names = {"testExecutor"}, rejectedHandler = ThreadPoolPolicyHandlers.DISCARD_POLICY) 
@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class, 
    SessionAutoConfiguration.class,
    DataSourceTransactionManagerAutoConfiguration.class, 
    JpaRepositoriesAutoConfiguration.class,
    JndiDataSourceAutoConfiguration.class, 
    JndiConnectionFactoryAutoConfiguration.class,
    RedisAutoConfiguration.class, RedisRepositoriesAutoConfiguration.class})
public class TestBoot {

    public static void main(String[] args) {
        SpringApplication.run(TestBoot.class, args);
    }   
}

spring-boot-starter-parent 1.4.5.RELEASE 的所有版本

我编写了一个 JUnit 测试来检查值并通过了测试。 唯一一次它不起作用是当我在 Spring Boot eureka 应用程序中 Autowiring 它时。有什么我可以做的，它不会 Autowiring 代理 bean 吗？我搜索了文档并查看了所有相关类，但我没有看到任何与它为什么是代理相关的内容。另外，为什么在通过代理访问时会给出错误的值？

最佳答案

似乎您缺少用于注册 ImportBeanDefinitionRegistrar 实例的代码(在您的示例中是 ExecutorEnumerationRegistrar ) 因此，有两种方法可以注册 ImportBeanDefinitionRegistrar，直接使用 @Import 注解，或者实现 ImportSelector 接口(interface)，后者可为您提供更通用的配置选项。

对于您的情况，只需在 Configuration 类上添加 @Import({ExecutorEnumerationRegistrar.class}) 即可。

@EnableDiscoveryClient
@ComponentScan("my.test.classes")
@ThreadPoolTaskExecutorCreator(names = {"testExecutor"}, rejectedHandler = ThreadPoolPolicyHandlers.DISCARD_POLICY)
// THIS IS REQUIRED
@Import({ExecutorEnumerationRegistrar.class})
// See Above
@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class, 
SessionAutoConfiguration.class,
DataSourceTransactionManagerAutoConfiguration.class, 
JpaRepositoriesAutoConfiguration.class,
JndiDataSourceAutoConfiguration.class, 
JndiConnectionFactoryAutoConfiguration.class,
RedisAutoConfiguration.class, RedisRepositoriesAutoConfiguration.class})
public class TestBoot {

    public static void main(String[] args) {
        SpringApplication.run(TestBoot.class, args);
    }   
}

在 Autowiring ThreadPoolTask​​Executor 的实例时，请记住使用 @Qualifier。查看示例组件

@Component
public class Component {

    @Autowired
    @Qualifier("testExecutor")
    private ThreadPoolTaskExecutor exec;

    // you methods
}

关于java - Spring 编程 bean Autowiring 为代理而不是目标，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/47360476/