Spring Bean没有自动连线

Question

我对从abstract类扩展的Spring beandefaultconfigurationservice初始化有一个问题。我完全卡住了。

类hiearchy如下所示：

public interface ConfigurationService {
    TaxPayer getTaxPayer();
} 

提到该类对需要初始化的服务很有用：

public abstract class BaseInitializationAwareService {

    private boolean initialized = false;

    public abstract void initialize();

    protected void checkInitialization() {
        if (!initialized) {
            initialize();
        }
    }

    protected void setInitialized() {
        this.initialized = true;
    }
}

public abstract class BaseConfigurationService extends BaseInitializationAwareService implements ConfigurationService {


}

    public class DefaultConfigurationService extends BaseConfigurationService {

        private TaxPayerService taxPayerService;

        @Autowired
        public void setTaxPayerService(TaxPayerService taxPayerService) {
            Assert.notNull(taxPayerService);
            this.taxPayerService = taxPayerService;
        }

public void initialize() {
        Optional<TaxPayer> dbtaxPayer = taxPayerService.getActiveTaxPayer();
        if (!dbtaxPayer.isPresent()) {
            throw new IllegalStateException("Tax payer setting not found!");
        }
        this.taxPayer = dbtaxPayer.get();
        setInitialized();
    }

    // the rest omitted...
    }

创建defaultconfigurationservicebean时：

@Bean
    public BaseConfigurationService configurationService() {
        DefaultConfigurationService configurationService = new DefaultConfigurationService();
        configurationService.initialize();
        return configurationService;
    }

则defaultconfigurationservice中的纳税人服务为null-似乎没有自动连线。

它能否与defaultconfigurationservice是从抽象类扩展而来的这一事实相联系？

@Bean
    public TaxPayerService taxPayerService() {
        DatabaseTaxPayerService taxPayer = new DatabaseTaxPayerService();
        return taxPayer;
    }

这个bean可能从未初始化过...

这是个例外：

org.springframework.beans.factory.UnsatisfiedDependencyException：创建名为“WebSecurityConfig.APISecurity”的bean时出错：通过方法“Set ContentNegotationStrategy”参数0表示的不满足的依赖关系；嵌套异常为org.springframework.beans.factory.unsatisfieddependencyexception：创建名为“org.springframework.web.servlet.config.annotation.delegatingwebmvcconfiguration”的bean时出错：通过方法“set configurers”参数0表示的不满足依赖项；嵌套异常为org.springframework.beans.factory.unsatisfieddependencyexception：创建名为“password recovercontroller”的bean时出错：通过方法“set userservice”参数0表示的不满足的依赖关系；嵌套异常为org.springframework.beans.factory.unsatisfieddependencyexception：创建名为“default userservice”的bean时出错：通过方法“set notificationservice”参数0表示的未满足的依赖关系；嵌套异常为org.springframework.beans.factory.unsatisfieddependencyexception：创建名称为“notification service”的bean时出错：通过方法“set configurationservice”参数0表示的不满足的依赖关系；嵌套异常为org.springframework.beans.factory.beanCreationException：创建类路径资源[com.example.config/appconfig.class]中定义的名为“configuration service”的bean时出错：通过工厂方法实例化bean失败；嵌套异常为org.springframework.beans.beanInstantiationException：无法实例化[com.example.services.baseConfigurationService]:工厂方法“configuration service”引发异常；嵌套异常是java.lang.NullPointerException

例如，需要baseConfigurationService的bean：

    public class EmailNotificationService extends BaseService implements NotificationService {

        private BaseConfigurationService configurationService;

@Autowired
    public void setConfigurationService(BaseConfigurationService configurationService) {
        Assert.notNull(configurationService);
        this.configurationService = configurationService;
    }

    // the rest omitted... 
    }

更新次数1

具有与其他Bean的内部依赖关系的Bean初始化示例：

@Bean
    public TransactionDataService transactionDataService() {
        return new DefaultTransactionDataService();
    }

public class DefaultTransactionDataService implements TransactionDataService {
    private PrivateKeyService privateKeyService;

    @Autowired
    public void setPrivateKeyService(PrivateKeyService privateKeyService) {
        Assert.notNull(privateKeyService);
        this.privateKeyService = privateKeyService;
    }
}

@Bean
    public PrivateKeyService privateKeyService() {
        return new DefaultPrivateKeyAwareService();
    }

而且起作用了。

Answer 1

它与您对Spring如何初始化bean的指导有关：

@bean用于显式声明单个bean，而不是像上面那样让Spring自动完成。它将bean的声明与类定义解耦，并允许您完全按照自己的选择来创建和配置bean。

因此，当您手动创建类的实例时，您也必须手动设置所有类字段。

@Bean
public BaseConfigurationService configurationService() {
    DefaultConfigurationService configurationService = new DefaultConfigurationService();
    configurationService.setTaxPayerService(taxPayerService());
    configurationService.initialize();
    return configurationService;
}

@Bean
public BaseConfigurationService configurationService() {
    DefaultConfigurationService configurationService = new DefaultConfigurationService(taxPayerService());
    configurationService.initialize();
    return configurationService;
}