關於Could not resolve placeholder 'foo' in value "${foo}"的問題

今天參考spring cloud config配置寫了一個service和client，啓動client的時候報錯：

Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'foo' in value "${foo}"
	at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:174) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:126) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.core.env.AbstractPropertyResolver.doResolvePlaceholders(AbstractPropertyResolver.java:236) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.core.env.AbstractPropertyResolver.resolveRequiredPlaceholders(AbstractPropertyResolver.java:210) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.context.support.PropertySourcesPlaceholderConfigurer$2.resolveStringValue(PropertySourcesPlaceholderConfigurer.java:172) ~[spring-context-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.resolveEmbeddedValue(AbstractBeanFactory.java:831) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1086) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	... 17 common frames omitted

奇怪了，我和網上的demo寫的差不多都一樣啊，除了端口號還有一些其他的，然後下載他demo運行了一下，他的運行沒問題，然後把我寫的和他對比了一下，不會是端口號吧……把config-service的端口號改爲8888，問題解決……

個人感覺應該是client-conf客戶端這塊應該有些地方沒配置，如果service-config那塊端口號不是8888的話。

補充一下，如果你的服務端的端口號寫的是默認的8888的話，還有問題，那就可能是你client配置的端口號被佔用了，window下cmd裏命令netstat,查看端口號是否被佔用

如果有朋友知道上述問題的其他解決方案，希望留下你的解答