페이지 이력

...

Maven의 dependency plugin에는 의존성 그래프를 트리 형식으로 보여주는 기능을 제공하는 goal(tree)가 있습니다. 그렇다면 이 그래프를 왜 확인해야 하나요? 답은 dependency의 충돌(conflict) 문제를 해결하기 위해서 입니다.

코드 블럭

language	text
linenumbers	true

# mvn dependency:tree
[INFO] Scanning for projects...
[INFO] 
[INFO] -------------< org.springframework.boot:spring-boot-ldap >--------------
[INFO] Building Spring Boot LDAP Sample 2.2.6.RELEASE
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- maven-dependency-plugin:3.1.2:tree (default-cli) @ spring-boot-ldap ---
[INFO] org.springframework.boot:spring-boot-ldap:jar:2.2.6.RELEASE
[INFO] +- org.springframework.boot:spring-boot-starter-web:jar:2.2.6.RELEASE:compile
[INFO] |  +- org.springframework.boot:spring-boot-starter:jar:2.2.6.RELEASE:compile
[INFO] |  |  +- org.springframework.boot:spring-boot:jar:2.2.6.RELEASE:compile
[INFO] |  |  +- org.springframework.boot:spring-boot-autoconfigure:jar:2.2.6.RELEASE:compile
[INFO] |  |  +- org.springframework.boot:spring-boot-starter-logging:jar:2.2.6.RELEASE:compile
[INFO] |  |  |  +- ch.qos.logback:logback-classic:jar:1.2.3:compile
[INFO] |  |  |  |  \- ch.qos.logback:logback-core:jar:1.2.3:compile
[INFO] |  |  |  +- org.apache.logging.log4j:log4j-to-slf4j:jar:2.12.1:compile
[INFO] |  |  |  |  \- org.apache.logging.log4j:log4j-api:jar:2.12.1:compile
[INFO] |  |  |  \- org.slf4j:jul-to-slf4j:jar:1.7.30:compile
[INFO] |  |  \- org.yaml:snakeyaml:jar:1.25:runtime
[INFO] |  +- org.springframework.boot:spring-boot-starter-json:jar:2.2.6.RELEASE:compile
[INFO] |  |  +- com.fasterxml.jackson.core:jackson-databind:jar:2.10.3:compile
[INFO] |  |  |  +- com.fasterxml.jackson.core:jackson-annotations:jar:2.10.3:compile
[INFO] |  |  |  \- com.fasterxml.jackson.core:jackson-core:jar:2.10.3:compile
[INFO] |  |  +- com.fasterxml.jackson.datatype:jackson-datatype-jdk8:jar:2.10.3:compile
[INFO] |  |  +- com.fasterxml.jackson.datatype:jackson-datatype-jsr310:jar:2.10.3:compile
[INFO] |  |  \- com.fasterxml.jackson.module:jackson-module-parameter-names:jar:2.10.3:compile
[INFO] |  +- org.springframework.boot:spring-boot-starter-validation:jar:2.2.6.RELEASE:compile
[INFO] |  |  +- jakarta.validation:jakarta.validation-api:jar:2.0.2:compile
[INFO] |  |  \- org.hibernate.validator:hibernate-validator:jar:6.0.18.Final:compile
[INFO] |  |     +- org.jboss.logging:jboss-logging:jar:3.4.1.Final:compile
[INFO] |  |     \- com.fasterxml:classmate:jar:1.5.1:compile
[INFO] |  +- org.springframework:spring-web:jar:5.2.5.RELEASE:compile
[INFO] |  \- org.springframework:spring-webmvc:jar:5.2.5.RELEASE:compile
[INFO] |     \- org.springframework:spring-expression:jar:5.2.5.RELEASE:compile
[INFO] +- javax.servlet:jstl:jar:1.2:compile
[INFO] +- org.springframework.data:spring-data-ldap:jar:2.2.6.RELEASE:compile
[INFO] |  +- org.springframework:spring-context:jar:5.2.5.RELEASE:compile
[INFO] |  +- org.springframework.ldap:spring-ldap-core:jar:2.3.2.RELEASE:compile
[INFO] |  +- org.springframework.data:spring-data-commons:jar:2.2.6.RELEASE:compile
[INFO] |  \- org.slf4j:slf4j-api:jar:1.7.30:compile
[INFO] +- org.springframework.data:spring-data-jpa:jar:2.2.6.RELEASE:compile
[INFO] |  +- org.springframework:spring-orm:jar:5.2.5.RELEASE:compile
[INFO] |  +- org.springframework:spring-aop:jar:5.2.5.RELEASE:compile
[INFO] |  +- org.springframework:spring-tx:jar:5.2.5.RELEASE:compile
[INFO] |  +- org.springframework:spring-beans:jar:5.2.5.RELEASE:compile
[INFO] |  +- org.springframework:spring-core:jar:5.2.5.RELEASE:compile
[INFO] |  |  \- org.springframework:spring-jcl:jar:5.2.5.RELEASE:compile
[INFO] |  \- org.aspectj:aspectjrt:jar:1.9.5:compile
[INFO] +- org.apache.directory.server:apacheds-core:jar:1.5.7:test
[INFO] |  +- org.apache.directory.server:apacheds-i18n:jar:1.5.7:test
[INFO] |  +- org.apache.directory.server:apacheds-core-api:jar:1.5.7:test
[INFO] |  |  \- org.apache.directory.server:apacheds-core-constants:jar:1.5.7:test
[INFO] |  +- org.apache.directory.server:apacheds-utils:jar:1.5.7:test
[INFO] |  +- bouncycastle:bcprov-jdk15:jar:140:test
[INFO] |  +- org.apache.directory.shared:shared-ldap:jar:0.9.19:test
[INFO] |  |  +- commons-collections:commons-collections:jar:3.2.1:test
[INFO] |  |  +- org.apache.directory.shared:shared-i18n:jar:0.9.19:test
[INFO] |  |  \- antlr:antlr:jar:2.7.7:test
[INFO] |  +- org.apache.directory.shared:shared-ldap-schema:jar:0.9.19:test
[INFO] |  +- org.apache.directory.shared:shared-ldap-schema-loader:jar:0.9.19:test
[INFO] |  +- org.apache.directory.shared:shared-ldap-schema-manager:jar:0.9.19:test
[INFO] |  +- org.apache.directory.shared:shared-cursor:jar:0.9.19:test
[INFO] |  +- org.apache.directory.shared:shared-ldap-jndi:jar:0.9.19:test
[INFO] |  +- org.apache.directory.shared:shared-asn1-codec:jar:0.9.19:test
[INFO] |  +- org.apache.directory.shared:shared-asn1:jar:0.9.19:test
[INFO] |  +- org.apache.directory.shared:shared-ldap-constants:jar:0.9.19:test
[INFO] |  +- org.apache.directory.shared:shared-ldap-converter:jar:0.9.19:test
[INFO] |  +- org.apache.directory.shared:shared-ldap-schema-dao:jar:0.9.19:test
[INFO] |  +- org.apache.directory.shared:shared-ldif:jar:0.9.19:test
[INFO] |  \- org.apache.directory.shared:shared-dsml-parser:jar:0.9.19:test
[INFO] |     +- dom4j:dom4j:jar:1.6.1:test
[INFO] |     |  \- xml-apis:xml-apis:jar:1.0.b2:test
[INFO] |     \- xpp3:xpp3:jar:1.1.4c:test
[INFO] +- org.apache.directory.server:apacheds-core-entry:jar:1.5.7:test
[INFO] +- org.apache.directory.server:apacheds-protocol-shared:jar:1.5.7:test
[INFO] |  \- org.apache.mina:mina-core:jar:2.0.0-RC1:test
[INFO] +- org.apache.directory.server:apacheds-protocol-ldap:jar:1.5.7:test
[INFO] |  +- org.apache.directory.server:apacheds-kerberos-shared:jar:1.5.7:test
[INFO] |  |  \- org.apache.directory.server:apacheds-core-jndi:jar:1.5.7:test
[INFO] |  \- org.apache.directory.server:apacheds-xdbm-tools:jar:1.5.7:test
[INFO] |     \- org.apache.directory.server:apacheds-xdbm-base:jar:1.5.7:test
[INFO] +- org.apache.directory.server:apacheds-server-jndi:jar:1.5.7:test
[INFO] |  +- org.apache.directory.server:apacheds-ldif-partition:jar:1.5.7:test
[INFO] |  |  +- org.apache.directory.server:apacheds-avl-partition:jar:1.5.7:test
[INFO] |  |  |  \- org.apache.directory.server:apacheds-core-avl:jar:1.5.7:test
[INFO] |  |  \- org.apache.directory.server:apacheds-core-mock:jar:1.5.7:test
[INFO] |  \- org.apache.directory.server:apacheds-jdbm-partition:jar:1.5.7:test
[INFO] |     +- org.apache.directory.server:apacheds-jdbm-store:jar:1.5.7:test
[INFO] |     |  \- org.apache.directory.server:apacheds-jdbm:jar:1.5.7:test
[INFO] |     \- org.apache.directory.server:apacheds-xdbm-search:jar:1.5.7:test
[INFO] +- org.springframework.boot:spring-boot-starter-tomcat:jar:2.2.6.RELEASE:provided
[INFO] |  +- jakarta.annotation:jakarta.annotation-api:jar:1.3.5:compile
[INFO] |  +- org.apache.tomcat.embed:tomcat-embed-core:jar:9.0.33:provided
[INFO] |  +- org.apache.tomcat.embed:tomcat-embed-el:jar:9.0.33:provided
[INFO] |  \- org.apache.tomcat.embed:tomcat-embed-websocket:jar:9.0.33:provided
[INFO] +- org.apache.tomcat.embed:tomcat-embed-jasper:jar:9.0.33:provided
[INFO] |  \- org.eclipse.jdt:ecj:jar:3.18.0:provided
[INFO] +- org.springframework.session:spring-session-jdbc:jar:2.2.2.RELEASE:compile
[INFO] |  +- org.springframework.session:spring-session-core:jar:2.2.2.RELEASE:compile
[INFO] |  \- org.springframework:spring-jdbc:jar:5.2.5.RELEASE:compile
[INFO] +- org.springframework.boot:spring-boot-starter-jdbc:jar:2.2.6.RELEASE:compile
[INFO] |  \- com.zaxxer:HikariCP:jar:3.4.2:compile
[INFO] +- com.h2database:h2:jar:1.4.200:compile
[INFO] +- org.springframework.boot:spring-boot-starter-test:jar:2.2.6.RELEASE:test
[INFO] |  +- org.springframework.boot:spring-boot-test:jar:2.2.6.RELEASE:test
[INFO] |  +- org.springframework.boot:spring-boot-test-autoconfigure:jar:2.2.6.RELEASE:test
[INFO] |  +- com.jayway.jsonpath:json-path:jar:2.4.0:test
[INFO] |  |  \- net.minidev:json-smart:jar:2.3:test
[INFO] |  |     \- net.minidev:accessors-smart:jar:1.2:test
[INFO] |  |        \- org.ow2.asm:asm:jar:5.0.4:test
[INFO] |  +- jakarta.xml.bind:jakarta.xml.bind-api:jar:2.3.3:test
[INFO] |  |  \- jakarta.activation:jakarta.activation-api:jar:1.2.2:test
[INFO] |  +- org.junit.jupiter:junit-jupiter:jar:5.5.2:test
[INFO] |  |  +- org.junit.jupiter:junit-jupiter-api:jar:5.5.2:test
[INFO] |  |  |  +- org.opentest4j:opentest4j:jar:1.2.0:test
[INFO] |  |  |  \- org.junit.platform:junit-platform-commons:jar:1.5.2:test
[INFO] |  |  +- org.junit.jupiter:junit-jupiter-params:jar:5.5.2:test
[INFO] |  |  \- org.junit.jupiter:junit-jupiter-engine:jar:5.5.2:test
[INFO] |  +- org.junit.vintage:junit-vintage-engine:jar:5.5.2:test
[INFO] |  |  +- org.apiguardian:apiguardian-api:jar:1.1.0:test
[INFO] |  |  +- org.junit.platform:junit-platform-engine:jar:1.5.2:test
[INFO] |  |  \- junit:junit:jar:4.12:test
[INFO] |  +- org.mockito:mockito-junit-jupiter:jar:3.1.0:test
[INFO] |  +- org.assertj:assertj-core:jar:3.13.2:test
[INFO] |  +- org.hamcrest:hamcrest:jar:2.1:test
[INFO] |  +- org.mockito:mockito-core:jar:3.1.0:test
[INFO] |  |  +- net.bytebuddy:byte-buddy:jar:1.10.8:test
[INFO] |  |  +- net.bytebuddy:byte-buddy-agent:jar:1.10.8:test
[INFO] |  |  \- org.objenesis:objenesis:jar:2.6:test
[INFO] |  +- org.skyscreamer:jsonassert:jar:1.5.0:test
[INFO] |  |  \- com.vaadin.external.google:android-json:jar:0.0.20131108.vaadin1:test
[INFO] |  +- org.springframework:spring-test:jar:5.2.5.RELEASE:test
[INFO] |  \- org.xmlunit:xmlunit-core:jar:2.6.4:test
[INFO] \- org.springframework.ldap:spring-ldap-test:jar:2.3.2.RELEASE:test
[INFO]    +- com.google.code.typica:typica:jar:1.3:test
[INFO]    |  +- commons-httpclient:commons-httpclient:jar:3.1:test
[INFO]    |  \- commons-codec:commons-codec:jar:1.13:test
[INFO]    +- commons-io:commons-io:jar:2.4:test
[INFO]    +- commons-lang:commons-lang:jar:2.6:test
[INFO]    +- javax.activation:activation:jar:1.1:test
[INFO]    \- org.springframework.ldap:spring-ldap-ldif-core:jar:2.3.2.RELEASE:test
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.953 s
[INFO] Finished at: 2020-04-20T01:54:58+09:00
[INFO] ------------------------------------------------------------------------

...

다음은 Java EE 버전에 따른 Java EE를 구성하는 표준들의 버전을 나열한 표입니다. 만약 Java EE 6를 지원하는 Tomcat을 사용한다면 Servlet API는 3.0을 사용해야 합니다. 그런데 dependency를 확인해보니 Servlet API 2.5 버전이라면 표준이 호환되지 않기 때문에 당연히 Tomcat이 제대로 실행되지 않는 문제가 발생합니다. 이러한 문제가 가장 찾기 어려운 문제중 하나입니다.

Specification	Java EE 6	Java EE 7	Java EE 8
Unified Expression Language (EL)	2.2	3.0	3.0
Servlet	3.0	3.1	4.0
Managed Beans	1.0	1.0	1.0
JavaServer Pages Standard Tag Library (JSTL)	1.2	1.2	1.2
JavaServer Pages (JSP)	2.2	2.3	2.3
JavaServer Faces (JSF)	2.0	2.2	2.3
Java Transaction API (JTA)	1.1	1.2	1.2
Java Persistence API (JPA)	2.0	2.1	2.2
Java API for WebSocket (WebSocket)	n/a	1.0	1.1
Java API for RESTful Web Services (JAX-RS)	1.1	2.0	2.1
Java API for JSON Processing (JSON-P)	n/a	1.0	1.1
Interceptors	1.1	1.2	1.2
Enterprise JavaBeans (EJB)	3.1 Lite	3.2 Lite	3.2
Dependency Injection for Java	1.0	1.0	1.0
Debugging Support for Other Languages (JSR-45)	1.0	1.0	1.0
Contexts and Dependency Injection for the Java EE Platform	1.0	1.1	2.0
Common Annotations for the Java Platform (JSR-250)	1.1	1.2	1.3
Bean Validation	1.0	1.1	2.0

다음은 Apache Tomcat의 버전에 적용된 표준의 버전을 나열한 표입니다. 웹 애플리케이션을 Spring Boot로 개발한다면, Spring WebMVC를 사용한다면 아래 버전을 유심히 확인해야 합니다.

Servlet Spec	JSP Spec	EL Spec	WebSocket Spec	Authentication (JASIC) Spec	Apache Tomcat Version	Latest Released Version	Supported Java Versions
5.0	3.0	4.0	2.0	2.0	10.0.x	10.0.0-M4 (alpha)	8 and later
4.0	2.3	3.0	1.1	1.1	9.0.x	9.0.34	8 and later
3.1	2.3	3.0	1.1	1.1	8.5.x	8.5.54	7 and later
3.1	2.3	3.0	1.1	N/A	8.0.x (superseded)	8.0.53 (superseded)	7 and later
3.0	2.2	2.2	1.1	N/A	7.0.x	7.0.103	6 and later (7 and later for WebSocket)
2.5	2.1	2.1	N/A	N/A	6.0.x (archived)	6.0.53 (archived)	5 and later
2.4	2.0	N/A	N/A	N/A	5.5.x (archived)	5.5.36 (archived)	1.4 and later
2.3	1.2	N/A	N/A	N/A	4.1.x (archived)	4.1.40 (archived)	1.3 and later
2.2	1.1	N/A	N/A	N/A	3.3.x (archived)	3.3.2 (archived)	1.1 and later

어떻게 충돌 문제를 해결할 수 있을까?

Dependency Conflict가 발생하면 다음과 같은 에러 메시지가 발생하거나 Classpath와 관련된 오류가 발생하는 것이 대표적이고, 그외 앞서 설명한 Java SE/Java EE 표준의 궁합이 맞지 않는 경우는 더 이상한 오류 메시지가 나올 수 있습니다.

...

가장 먼저 확인해야하는 것은 Dependency Tree를 확인하고 어떤 dependency라 문제가 되는지 찾는 것입니다. 아래는 commons-collections 의 충돌 이슈를 해결하기 위해서 별도 옵션을 지정했습니다.

코드 블럭

language	text
linenumbers	true

# mvn dependency:tree -Dverbose -Dincludes=commons-collections
... 생략
[INFO] [dependency:tree]
[INFO] org.apache.maven.plugins:maven-dependency-plugin:maven-plugin:2.0-alpha-5-SNAPSHOT
[INFO] +- org.apache.maven.reporting:maven-reporting-impl:jar:2.0.4:compile
[INFO] |  \- commons-validator:commons-validator:jar:1.2.0:compile
[INFO] |     \- commons-digester:commons-digester:jar:1.6:compile
[INFO] |        \- (commons-collections:commons-collections:jar:2.1:compile - omitted for conflict with 2.0)
[INFO] \- org.apache.maven.doxia:doxia-site-renderer:jar:1.0-alpha-8:compile
[INFO]    \- org.codehaus.plexus:plexus-velocity:jar:1.1.3:compile
[INFO]       \- commons-collections:commons-collections:jar:2.0:compile

...

일단 문제가 되는 dependency를 찾으면 다음과 같이 <exclude> 처리를 합니다. 이렇게 <exclude> 처리를 하면 해당 dependency는 아예 제거됩니다.

코드 블럭

language	xml
linenumbers	true

<project>
  ...
  <dependencies>
    <dependency>
      <groupId>sample.ProjectA</groupId>
      <artifactId>Project-A</artifactId>
      <version>1.0</version>
      <scope>compile</scope>
      <exclusions>
        <exclusion>  <!-- declare the exclusion here -->
          <groupId>sample.ProjectB</groupId>
          <artifactId>Project-B</artifactId>
        </exclusion>
      </exclusions> 
    </dependency>
  </dependencies>
</project>

...

페이지 트리

버전 비교

이전 버전 9

새 버전 10

키

어떻게 충돌 문제를 해결할 수 있을까?