Question

我是春天的新手。我遇到了Spring-Boot的问题。我正在尝试将外部配置文件中的字段自动装入自动装配的bean中。我有以下课程

App.java

public class App {

@Autowired
private Service service;

public static void main(String[] args) {

    final SpringApplication app = new SpringApplication(App.class);
    //app.setShowBanner(false);
    app.run();
}

@PostConstruct
public void foo() {
    System.out.println("Instantiated service name = " + service.serviceName);
}
}

AppConfig.java

@Configuration
@ConfigurationProperties
public class AppConfig {

@Bean
public Service service()    {
    return new Service1();
}
}

服务接口

public interface Service {
    public String serviceName ="";
    public void getHistory(int days , Location location );
    public void getForecast(int days , Location location );
}

服务1

@Configurable
@ConfigurationProperties
public class Service1 implements Service {

@Autowired
@Value("${serviceName}") 
public String serviceName;
//Available in external configuration file.
//This autowiring is not reflected in the main method of the application.



public void getHistory(int days , Location location)
{
    //history code
}

public void getForecast(int days , Location location )
{
    //forecast code
}
}

我无法在App类的postconstruct方法中显示服务名称变量。我这样做了吗？

Answer 1

您可以通过不同方式加载属性：

想象一下以下由spring-boot自动加载的application.properties。

spring.app.serviceName=Boot demo
spring.app.version=1.0.0

使用@Value

注入值

@Service
public class ServiceImpl implements Service {

@Value("${spring.app.serviceName}") 
public String serviceName;

}

使用@ConfigurationProperties

注入值

@ConfigurationProperties(prefix="spring.app")
public class ApplicationProperties {

   private String serviceName;

   private String version;

   //setters and getters
}

您可以使用@Autowired

@Service
public class ServiceImpl implements Service {

@Autowired
public ApplicationProperties applicationProperties;

}

您可以注意到前缀为spring.app，然后spring-boot将匹配属性前缀，并查找serviceName和version，并注入值。

Answer 2

考虑到您在顶部包中注明了App和@SpringBootApplication类，您可以将App放在serviceName内并使用application.properties。如果您已经在配置上使用@Value("${serviceName}")它将会发生冲突，请不要在课程上使用@Component，因此@Bean与@Autowired

有关详细信息，请参阅docs

你会以

之类的结尾

@Value

当你有@ Component / @ Service / @ Repository

时，不需要@Bean声明

@Service // @Component specialization
public class Service1 implements Service {

@Value("${serviceName}") 
public String serviceName;
//Available in external configuration file.
//This autowiring is not reflected in the main method of the application.



public void getHistory(int days , Location location)
{
    //history code
}

public void getForecast(int days , Location location )
{
    //forecast code
}
}

你的主要班级

@Configuration
public class AppConfig {  //other stuff here not duplicated beans  }

Spring在自动装配的bean中自动装配属性

2 个答案: