【Spring Boot】常见问题与解决方案

使用setLazyInitialization懒加载时导致某些@Bean或@Autowired等无法加载

示范

@SpringBootApplication
public class XxxxApplication {
    public static void main(String[] args) {
        SpringApplication xxx = new SpringApplication(XxxxApplication.class);
        xxx.setLazyInitialization(true);
        application.run(args);
        System.out.println("启动成功");
    }
}

解决方案：

方法1：去掉xxx.setLazyInitialization(true);
方法2：在 @Component 注解中显式设置 @Lazy(false)，强制 Spring 在启动时立即加载该 Bean。

遇到使用@Qualifier(value=“taskExecutor”)无法注入的情况下解决方案

方案1、中显式转换

@Autowired
    public TaskService(@Qualifier(value="taskExecutor") Executor executor) {
        if (executor instanceof ThreadPoolTaskExecutor) {
            this.taskExecutor = (ThreadPoolTaskExecutor) executor;
        } else {
            throw new IllegalArgumentException("Injected executor is not of type ThreadPoolTaskExecutor");
        }
    }

方案2、使用 ObjectProvider 动态获取 Bean

@Autowired
public TaskService(ObjectProvider<Executor> executorProvider) {
    this.taskExecutor = (ThreadPoolTaskExecutor) executorProvider.getIfAvailable();
    if (this.taskExecutor == null) {
        throw new IllegalStateException("No ThreadPoolTaskExecutor bean found");
    }
}

排查Spring 的 Bean 定义注入情况

@PostConstruct
public void printAllBeans() {
    System.out.println("Registered Beans:");
    for (String beanName : applicationContext.getBeanDefinitionNames()) {
        Object bean = applicationContext.getBean(beanName);
        System.out.println(beanName + " : " + bean.getClass().getName());
    }
}