操作：
在项目resouces目录下存放文件，然后在代码中尝试获取，代码如下：
ClassPathResource resource = new ClassPathResource("XXX.cfg");
File file = resource.getFile();
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执行jar，项目运行，调用的时候会抛出如下异常：
Caused by: java.io.FileNotFoundException: class path resource [XXX.cfg] cannot be resolved to absolute file path because it does not reside in the file system: jar:file:/D:/sunmnet/JetBrains/workspace/xxx/target/xxx-1.0-SNAPSHOT.jar!/BOOT-INF/classes!/XXX.cfg
at org.springframework.util.ResourceUtils.getFile(ResourceUtils.java:215) ~[spring-core-4.3.12.RELEASE.jar!/:4.3.12.RELEASE]
at org.springframework.core.io.AbstractFileResolvingResource.getFile(AbstractFileResolvingResource.java:53) ~[spring-core-4.3.12.RELEASE.jar!/:4.3.12.RELEASE]
at hello.whz.Application.lambda$lookup$0(Application.java:30) [classes!/:1.0-SNAPSHOT]
at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:732) [spring-boot-1.5.8.RELEASE.jar!/:1.5.8.RELEASE]
... 14 common frames omitted
复制代码原因：
项目打成jar包后，资源文件也存在于jar包中，文件的绝对路径是jar:file:/D:/sunmnet/JetBrains/workspace/xxx/target/xxx-1.0-SNAPSHOT.jar!/BOOT-INF/classes!/XXX.cfg但在运行过程中，spring是不允许直接访问jar包内的文件的，所以会报错。
解决：
采用读取流的方式访问文件：
ClassPathResource resource = new ClassPathResource("application.yml");
InputStream inputStream = resource.getInputStream();
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