缘起 ：项目需读取nacos中动态的TDengine数据库连接信息并提取IP，一个并不复杂的操作，但作为一个nacos知识浅薄的菜鸡，我愣是捯饬了几个小时……惭愧惭愧……

异常代码

@Data
@Component
public class TaosLink {
//    @Value("${spring.datasource.dynamic.datasource.taos.url}")
    @Value("${spring.datasource.tdengine.datasource.jdbc-url}")
    private String url;
}

报错信息

报错核心：

Injection of autowired dependencies failed; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder ‘spring.datasource.tdengine.datasource.jdbc-url’ in value “${spring.datasource.tdengine.datasource.jdbc-url}”

具体报错：

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'handleData' defined in file [E:\3H1Work\WanRuiIOT\iot-platform\blade-service\dl-iot-manager\target\classes\org\springblade\modules\component\netty\ws\service\HandleData.class]: Unsatisfied dependency expressed through constructor parameter 4; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'environmentalKrDeviceServiceImpl' defined in file [E:\3H1Work\WanRuiIOT\iot-platform\blade-service\dl-iot-manager\target\classes\org\springblade\modules\dataScreen\service\impl\EnvironmentalKrDeviceServiceImpl.class]: Unsatisfied dependency expressed through constructor parameter 7; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'purityAnalysisServiceImpl' defined in file [E:\3H1Work\WanRuiIOT\iot-platform\blade-service\dl-iot-manager\target\classes\org\springblade\modules\dataScreen\service\impl\PurityAnalysisServiceImpl.class]: Unsatisfied dependency expressed through constructor parameter 5; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'taosLink': Injection of autowired dependencies failed; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'spring.datasource.tdengine.datasource.jdbc-url' in value "${spring.datasource.tdengine.datasource.jdbc-url}"
	at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:800)
	at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:229)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1372)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1222)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542)
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:955)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583)
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:147)
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:734)
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:408)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:308)
	at org.springframework.boot.builder.SpringApplicationBuilder.run(SpringApplicationBuilder.java:164)
	at org.springblade.core.launch.BladeApplication.run(BladeApplication.java:50)

异常原因

以上报错通常是由于配置文件异常导致的，即没有找到对应的配置信息。首先我们需要查看当前模块的nacos配置信息，并核验当前nacos所处的命名空间是否包含以上异常代码中的配置属性。

排查过程

• 1、查看nacos配置信息（group为dl-iot-manage）

• 2、根据nacos配置信息核验需属性是否在对应的配置文件内(nacos中spring.datasource.tdengine.datasource.jdbc-url 所属配置的group为 dl-iot-link 与 项目的nacos配置不同，即产生异常的根本原因， 修改项目中nacos配置信息或将所需的配置属性添加到nacos配置信息指定的配置文件，即可解决异常)

• 3、将配置属性地址修改为项目nacos配置中指定的命名空间和组，然后重启，报错消失

  • 无异常代码

    @Data
    @Component
    public class TaosLink {
    	@Value("${spring.datasource.dynamic.datasource.taos.url}")
        private String url;
    }
    

  • 与项目中nacos配置匹配的命名空间和组

    

• 解析配置属性，提取IP地址

      // 注入配置所属的类
  	@Resource
  	private final TaosLink taosLink;
  
      public String getTaosUrl(){
          String url = taosLink.getUrl();
          // 提取IP地址的正则表达式
          String regex = "((2[0-4]\\d|25[0-5]|[01]?\\d\\d?)\\.){3}(2[0-4]\\d|25[0-5]|[01]?\\d\\d?)";
  
          Pattern pattern = Pattern.compile(regex);
          Matcher matcher = pattern.matcher(url);
          String group = "";
          if (matcher.find()){
              group = matcher.group();
          }
          log.info("IP信息: " + group);
          return String.format(IotRedisContant.TAOS_URL, group);
      }
  

• 运行结果
  

项目中nacos配置正常仍无法获取属性

确认项目中nacos的配置和nacos中yaml文件的基础信息无误后仍无法读取指定属性值，建议检查项目运行时本地生成的yaml文件，查看文件中是否含有所需属性。如果本地不存在yaml文件则说明nacos连接信息有误，需检查nacos的运行状况；如果本地存在yaml文件但文件中没有所需属性，则说明nacos中部署的配置文件不含所需属性。本地生成的文件地址如下：

• 项目运行产生的nacos文件夹

  

• 文件夹中生成的yaml文件

  

Over！