java - Spring Bean在配置类中初始化后仍然为null

Question

这是我在配置类中的 bean 定义。

@Bean(name = "applicationPropertiesDataService")
public com.ing.app.data.ApplicationPropertiesDataService 
applicationPropertiesDataService() {
    return new com.ing.app.data.ApplicationPropertiesDataService();
}

这是我使用上述 bean 的类的 bean 定义。

@Bean(name = "appRestTemplate")
public AppRestTemplate appRestTemplate() {
    return new AppRestTemplate();
}

这是 AppRestTemplate 类。我将 Autowiring 的“applicationPropertiesDataService”bean 设置为 null，即使该 bean 在 AppRestTemplate bean 之前实例化(我通过在配置类中放置调试点来检查它)

import org.springframework.web.client.RestTemplate;

import com.ing.app.data.ApplicationPropertiesDataService;
import com.ing.app.interceptor.LoggingClientHttpRequestInterceptor;

public class AppRestTemplate extends RestTemplate {

@Autowired
private ApplicationPropertiesDataService applicationPropertiesDataService;

public AppRestTemplate() {

    SimpleClientHttpRequestFactory requestFactory = new SimpleClientHttpRequestFactory();
    requestFactory.setOutputStreaming(false);
    BufferingClientHttpRequestFactory bufferingClientHttpRequestFactory =
        new BufferingClientHttpRequestFactory(requestFactory);
    this.setRequestFactory(bufferingClientHttpRequestFactory);

    if (isLoggingEnabled()) {

    List<ClientHttpRequestInterceptor> interceptors = new ArrayList<>();
        interceptors.add(new LoggingClientHttpRequestInterceptor());
        this.setInterceptors(interceptors);
    }
}
}

private boolean isLoggingEnabled() {
    boolean isLoggingEnabled = false;
    Optional<ApplicationProperties> applicationProperties = applicationPropertiesDataService.findByCategoryAndName(
        Constant.APPLICATION_PROPERTIES_CATEGORY_AUDIT_LOGGING, Constant.APPLICATION_PROPERTIES_AUDIT_LOGGING);

    if (applicationProperties.isPresent()) {
        isLoggingEnabled = Constant.CONSTANT_Y.equalsIgnoreCase(applicationProperties.get().getValue());
    }
    return isLoggingEnabled;
}

我无法弄清楚为什么 Autowiring 的 applicationPropertiesDataService bean 为 null。任何帮助，将不胜感激。谢谢。

Answer 1

您手动调用new AppRestTemplate();，这会绕过CDI(上下文和依赖注入(inject))。要获得 Autowired，Spring 必须创建 bean，而不是您。

有很多解决方案。你可以这样做:

@Bean(name = "appRestTemplate")
public AppRestTemplate appRestTemplate(ApplicationPropertiesDataService applicationPropertiesDataService) {
    return new AppRestTemplate(applicationPropertiesDataService);
}

和

public class AppRestTemplate extends RestTemplate {

    private final ApplicationPropertiesDataService applicationPropertiesDataService;

    @Autowired
    public AppRestTemplate(ApplicationPropertiesDataService applicationPropertiesDataService) {
        this.applicationPropertiesDataService = applicationPropertiesDataService;
    }
}