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Spring外部化配置的幾種技巧分享

更新時(shí)間：2021年06月21日 14:10:41 作者：johnwonder

在油管上看了龍之春的一個(gè)Spring tips 視頻，講述Spring外部化配置的幾種技巧，收獲頗多，想拿出來(lái)給大家分享下。對(duì)spring感興趣的朋友可以了解下本文

正文

Envrionment 獲取外部配置

@Log4j2
@SpringBootApplication
public class ConfigurationApplication {

    public static void main(String[] args) {
        SpringApplication.run(ConfigurationApplication.class, args);
    }
    @Bean
    ApplicationRunner applicationRunner(Environment environment){

        return  args -> {
            log.info("user.name : {}",environment.getProperty("user.name"));
        };
    }
}

修改Spring默認(rèn)配置文件名稱

啟動(dòng)程序參數(shù)中加入如下配置：

--spring.config.name=app

Value注解配置來(lái)源

配置文件

@Bean
ApplicationRunner applicationRunner(Environment environment,
                           @Value("${greeting.message:hello boy}") String message){

   return  args -> {
      log.info("from application.properties user.name : {}",environment.getProperty("user.name"));
      log.info("from application.properties greeting.message : {}",message);

   };
}

默認(rèn)值

value注解通過(guò)冒號(hào)來(lái)配置默認(rèn)值：

@Value("${greeting.message:hello boy}")

獲取環(huán)境變量值

獲取程序參數(shù)值

外部化配置文件優(yōu)先級(jí)問(wèn)題

如果有application.properties在springboot 啟動(dòng)jar包同一目錄，會(huì)優(yōu)先讀取這個(gè)文件中的配置。

Autowire注入ConfigurableEnvrionment

public static void main(String[] args) {

        new SpringApplicationBuilder()
                .sources(ConfigurationApplication.class)
                .run(args);
}

@Autowired
void getConfigurableEnvrionment(ConfigurableEnvironment environment) {
    environment.getPropertySources().addLast(new MyPropertySource());
}

ApplicationInitialiazer 配置

    public static void main(String[] args) {

        new SpringApplicationBuilder()
                .sources(ConfigurationApplication.class)
                .initializers(applicationContext ->
                 applicationContext.getEnvironment().getPropertySources().addLast(new MyPropertySource()))
                .run(args);
    }

static  class  MyPropertySource extends PropertySource<String>{


   public MyPropertySource() {
      super("myproperty");
   }

   @Override
   public Object getProperty(String name) {

      if(name.equalsIgnoreCase("author-name")){
         return  "john";
      }
      return null;
   }
}

然后通過(guò)@Value注解注入獲取author-name：

    @Bean
    ApplicationRunner applicationRunner(Environment environment,
                                        @Value("${greeting.message:hello boy}") String message,
                                        @Value("${author-name}") String name){

        return  args -> {
            log.info("from application.properties user.name : {}",environment.getProperty("user.name"));
            log.info("from application.properties author.name : {}",name);
        };
    }