通过获取已经创建的RestTemplate来拦截RestTemplate

Question

我有拦截RestTemplate的逻辑，我在配置文件(SecurityConfiguration.java)中添加/注册这个RestTemplate，但是我想通过获取已经注册的RestTemplate对象从另一个配置文件中添加拦截器：

public class TranslogRestTemplateCondition implements Condition {

    @Override
    public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
        boolean isRestTemplate = false;
        try {
            if (context.getBeanFactory() != null) {
                isRestTemplate = (context.getBeanFactory().getBean(RestTemplate.class) != null);
            }
        } catch (BeansException e) {
            return false;
        }
        return isRestTemplate;
    }
}

配置类：

@Configuration
public class RestTemplateConfig {

    private final MyInterceptor myInterceptor;

    @Value("${com.pqr.you.rest.enabled:true}")
    private boolean transEnabled;

    @Autowired
    public RestTemplateConfig(MyInterceptor myInterceptor) {
        this.myInterceptor = myInterceptor;
    }

    @Autowired
    private ApplicationContext appContext;

    // The logic added below is not working for me
    @Bean
    @Conditional(TranslogRestTemplateCondition.class)
    public RestTemplate addInterceptor(ApplicationContext appContext) {
        RestTemplate restTemplate = appContext.getBean(RestTemplate.class);
        if (transEnabled) {
            List<ClientHttpRequestInterceptor> interceptors = restTemplate.getInterceptors();
            interceptors.add(myInterceptor);
            restTemplate.setInterceptors(interceptors);
        }
        return restTemplate;
    }
}

RestTemplate的实际逻辑(它将与所需的拦截器一起返回)和一些其他值(在返回此restTemplate时，我的拦截器也需要在这里添加，而不超过现有值)或，方法是接受下面的restTempalte对象并将MyInterceptor添加到restTemplate.中。

@Configuration
public class SecurityConfiguration {

    @Bean
    public AbcInterceptor abcRequestInterceptor(XyzService xyzService) {
        return new AbcInterceptor("abc-app", null, xyzService);
    }

    // I dont want to create bean here 
    /*@Bean
    public MyInterceptor myInterceptor() {
        return new MyInterceptor();
    }*/ 

    @Bean
    public RestTemplate restTemplate(AbcRequestInterceptor abcRequestInterceptor) {
        RestTemplate restTemplate = new RestTemplate();
        List<ClientHttpRequestInterceptor> interceptors = new ArrayList<>();
        interceptors.add(abcRequestInterceptor);
        //interceptors.add(myInterceptor); // I dont want to add this interceptor here
        restTemplate.setInterceptors(interceptors);
        return restTemplate;
    }
}

Answer 1

我认为在这种情况下您需要的是一个BeanPostProcessor，而不是一个Condition类。如果bean存在，它将允许您修改它。您可以创建如下所示的类，而不是RestTemplateConfiguration类和Condition

@Configuration
public class RestTemplatePostProcessor implements BeanPostProcessor {

    @Value("${com.pqr.you.rest.enabled:true}")
    private boolean transEnabled;

    @Bean
    MyInterceptor myInterceptor() {
        return new MyInterceptor();
    }

    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {

        if (bean instanceof RestTemplate) { // or you can check by beanName if you like
            final RestTemplate restTemplate = (RestTemplate) bean;

            if (transEnabled) {
                List<ClientHttpRequestInterceptor> interceptors = restTemplate.getInterceptors();
                interceptors.add(myInterceptor());
                restTemplate.setInterceptors(interceptors);
            }
            return restTemplate;
        }
        return bean;
    }
}

注意，在您的代码中，您正在尝试创建另一个RestTemplate实例(名为"addInterceptor")，这似乎是不想要的。