Java Spring自动关联自动关联bean中的属性

我是春天的新手。我的弹簧靴有问题。我正在尝试将一个字段从外部配置文件自动关联到一个自动关联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service name变量。我这样做对吗？

考虑到您的class

App

带有

@SpringBootApplication

和

App

类的注释，您可以将

serviceName

放在

应用程序中。属性

并使用

@Value（${serviceName}”）

注入它。不要在类上使用

@Component

，如果您已经在配置上使用

@Bean

，它将发生冲突，因此

@Autowired

与

@Value

有关更多信息，请参阅

你会以这样的方式结束

@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
}
}

当您有@Component/@Service/@Repository时，不需要@Bean声明

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

你的主课呢

    package com.app;

    @SpringBootApplication // contains @EnableAutoConfiguration @ComponentScan @Configuration   
    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);
    }
    }

---

您可以通过不同的方式加载属性：

想象一下下面的application.properties由spring引导自动加载

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

从另一个类访问此属性

@Service
public class ServiceImpl implements Service {

@Autowired
public ApplicationProperties applicationProperties;

}

正如您所注意到的，前缀将是

spring.app

，然后spring引导将属性前缀与之匹配，并查找

serviceName

和

version

，然后将注入值