Spring将TaskExecutor和TaskScheduler用作相同类型

Question

我有以下配置：

@org.springframework.context.annotation.Configuration
@EnableJpaRepositories
@EnableAsync
@EnableScheduling
public class MyConfiguration {


    @Bean
    public TaskExecutor taskExecutor() {

        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(10);
        executor.setMaxPoolSize(20);
        executor.setQueueCapacity(50);
        return executor;
    }

    @Bean
    public TaskScheduler taskScheduler() {

        ThreadPoolTaskScheduler scheduler = new ThreadPoolTaskScheduler();
        scheduler.setPoolSize(10);
        return scheduler;
    }

}

然后，我有一个侦听ContextRefreshEvents的类，例如：

@Component
public class ScreenerScheduler implements ApplicationListener<ContextRefreshedEvent> {

    @Inject
    private TaskScheduler scheduler;

    @Inject
    private ApplicationContext context;

    @Override
    public void onApplicationEvent(ContextRefreshedEvent event) {
}

当我运行应用程序（网络）时，我得到：

Error creating bean with name 'screenerJobExecutor': Injection of autowired dependencies  failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private org.springframework.core.task.TaskExecutor example.workflow.ScreenerJobExecutor.executor; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [org.springframework.core.task.TaskExecutor] is defined: expected single matching bean but found 2: taskExecutor,taskScheduler

任何人都可以帮助弄清楚为什么spring可以看到TaskScheuler的两种可能的类型？

Answer 1

这个@Bean方法

@Bean
public TaskScheduler taskScheduler() {

返回类型ThreadPoolTaskScheduler为

public class ThreadPoolTaskScheduler extends ExecutorConfigurationSupport
    implements TaskScheduler, SchedulingTaskExecutor {

所以它适合两个接口，TaskScheduler和TaskExecutor（超类型SchedulingTaskExecutor）。

如果您尝试注入一个TaskExecutor类似堆栈跟踪这样的类型的字段

Could not autowire field: private org.springframework.core.task.TaskExecutor...

Spring无法选择哪一个。

仅ApplicationContext当您尝试从中拉出Bean的Bean已经初始化了Bean时，例如在Web应用程序中，您的根上下文将MyConfiguration在其中注册，而Servlet上下文将声明您的screenerJobExecutorBean需要注入一个A。类型的bean TaskExecutor。

您确实可以使用

@Qualifier(value = "taskExecutor")

为了解决这种特殊情况，Spring将使用bean名称而不是bean类型来满足注入目标。