[spring] read excel file

maven : pom.xml에 apache poi, poi-ooxml "같은 버전으로" 추가 (다른 버전 지원 안됨 https://poi.apache.org/help/faq.html 19번 참조) 이거 안해서 계속 에러남 ㅆㅃ

https://mvnrepository.com/artifact/org.apache.poi/poi

    <!-- https://mvnrepository.com/artifact/org.apache.poi/poi -->
    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi</artifactId>
        <version>4.1.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi-ooxml</artifactId>
        <version>4.1.1</version>
    </dependency>