提示：启动springboot服务，发现加载不了配置文件，resources目录下的.yml配置文件图标显示也异常。
一、错误日志
2022-03-22 10:59:40.815 WARN --- ConfigServletWebServerApplicationContext Line:558 - Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanDefinitionStoreException: Failed to parse configuration class [com.lmm.third.ComThirdApplication]; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'spring.profiles.active' in value "classpath:mongodb-${spring.profiles.active}.properties"
2022-03-22 10:59:40.825 ERROR --- o.s.boot.SpringApplication Line:826 - Application run failed
org.springframework.beans.factory.BeanDefinitionStoreException: Failed to parse configuration class [com.lmm.third.ComThirdApplication]; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'spring.profiles.active' in value "classpath:mongodb-${spring.profiles.active}.properties"
at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:188)
at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:319)
at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:236)
at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:275)
at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:95)
at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:706)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:532)
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747)
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:315)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215)
at com.lmm.third.ComThirdApplication.main(ComThirdApplication.java:15)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49)
Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'spring.profiles.active' in value "classpath:mongodb-${spring.profiles.active}.properties"
at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:178)
at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:124)
at org.springframework.core.env.AbstractPropertyResolver.doResolvePlaceholders(AbstractPropertyResolver.java:236)
at org.springframework.core.env.AbstractPropertyResolver.resolveRequiredPlaceholders(AbstractPropertyResolver.java:210)
at org.springframework.core.env.AbstractEnvironment.resolveRequiredPlaceholders(AbstractEnvironment.java:571)
at org.springframework.context.annotation.ConfigurationClassParser.processPropertySource(ConfigurationClassParser.java:460)
at org.springframework.context.annotation.ConfigurationClassParser.doProcessConfigurationClass(ConfigurationClassParser.java:279)
at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:249)
at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:198)
at org.springframework.context.annotation.ConfigurationClassParser.doProcessConfigurationClass(ConfigurationClassParser.java:303)
at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:249)
at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:206)
at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:174)
... 18 common frames omitted
二、resource目录：
正常的resources资源目录显示：
非正常resources资源目录显示：
三、解决
1、在项目的pom.xml文件的<build></build>标签内添加如下代码：
<resources>
<!-- 该节点会扫描src/main/java目录，若该目录下有配置文件，则需要添加以下配置，保证文件能够被扫描和加载到 -->
<resource>
<directory>src/main/java</directory>
<includes>
<!-- 根据目录下的文件配置需要扫描的文件类型 -->
<include>**/*.yml</include>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>false</filtering>
</resource>
<!-- 该节点会扫描src/main/resources，一般资源文件和配置文件会放在该目录下 -->
<resource>
<directory>src/main/resources</directory>
<includes>
<!-- 根据目录下的文件配置需要扫描的文件类型 -->
<include>**/*.yml</include>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>false</filtering>
</resource>
</resources>
2、另外，如果src/main/resources目录下还有其他需要扫描指定位置的包，那么配置resource节点的时候，要把resource节点设置在扫描src/main/resources之前，如下示例：
<resources>
<!-- 该节点会扫描src/main/java目录，若该目录下有配置文件，则需要添加以下配置，保证文件能够被扫描和加载到 -->
<resource>
<directory>src/main/java</directory>
<includes>
<!-- 根据目录下的文件配置需要扫描的文件类型 -->
<include>**/*.properties</include>
</includes>
<filtering>false</filtering>
</resource>
<!-- 扫描指定目录的配置 -->
<resource>
<directory>${project.basedir}/src/main/resources/lib</directory>
<targetPath>BOOT-INF/lib/</targetPath>
<includes>
<include>**/cloud-webapi-sdk7.0.jar</include>
</includes>
</resource>
<!-- 该节点会扫描src/main/resources，一般资源文件和配置文件会放在该目录下 -->
<resource>
<directory>src/main/resources</directory>
<includes>
<!-- 根据目录下的文件配置需要扫描的文件类型 -->
<include>**/*.yml</include>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>false</filtering>
</resource>
</resources>
3、<resource>节点中如果加了<targetPath>子节点，要注意指定目标目录位置是否正确，否则也可能会导致扫描文件失败，失败案例如下：
<resources>
<resource>
<directory>${project.basedir}/src/main/resources/lib</directory>
<targetPath>BOOT-INF/lib/</targetPath>
<includes>
<include>**/k3cloud-webapi-sdk7.9.jar</include>
</includes>
</resource>
<resource>
<directory>src/main/resources</directory>
<!-- 上面提到的异常，就是因为这个地方指向了错误的目录，导致配置文件扫描不到，最后把这个节点去掉，就能正常启动服务了 -->
<targetPath>BOOT-INF/classes/</targetPath>
</resource>
</resources>
总结
踩多一点的坑没什么坏处，还能总结经验，日后在开发当中才能更加细心，遇到类似的异常也能更快排查出来！