Spring Bean-带参数的构造函数

Question

I see an error in the constructor which says

"String queueName" cannot be autowired.

I have AmazonSQSAsync component defined in another class but not queueName . Why is the constructor trying to autowire the parameters and how can I resolve this?

@Configuration
public class SqsQueueHealthIndicator extends AbstractHealthIndicator {

    private final AmazonSQSAsync amazonSQSAsync;
    private final String queueName;

    public SqsQueueHealthIndicator(AmazonSQSAsync amazonSQSAsync, String queueName) {
        this.amazonSQSAsync = amazonSQSAsync;
        this.queueName = queueName;
    }

    @Override
    protected void doHealthCheck(Health.Builder builder) {
        try {
            amazonSQSAsync.getQueueUrl(queueName);
            builder.up();
        } catch (QueueDoesNotExistException e) {
            builder.down(e);
        }
    }

    @Bean
    SqsQueueHealthIndicator queueHealthIndicator(@Autowired AmazonSQSAsync amazonSQSAsync, @Value("${url}") String queueName) {
        return new SqsQueueHealthIndicator(amazonSQSAsync, queueName);
    }

    @Bean
    SqsQueueHealthIndicator deadLetterQueueHealthIndicator(@Autowired AmazonSQSAsync amazonSQSAsync, @Value("${dlqurl}") String deadLetterQueueName) {
        return new SqsQueueHealthIndicator(amazonSQSAsync, deadLetterQueueName);
    }

}

Answer 1

Because you're declaring it as final so its value must be initialized.

You did not provide default value so Spring understand its value will be injected.

So you have 2 options:

1. Remove the final modifier. Use @Value to inject your value from config file.

2. Create a bean type of String and inject it. You should name it:

    @Bean("queueName") public String getQueueName {return "xyz";} 

And inject like:

    @Autowire
    @Qualifier("queueName")
    private final String queueName;

In normal circumstance, the option 1 is the go-to.