[Maven] The container 'Maven Dependencies' references non existing library 다운로드 못하는 문제

개발환경

1. STS 버전 : 4.13.1

2. JDK 버전 : OpenJDK 11.0.14_9_x64

3. Tomcat 버전 : 9.0.56

4. Maven 버전 : 3.8.4

5. Spring 버전 : Spring Boot 2.6.3

---

Spring Boot 를 설정하면서, Tomcat을 추가해 뒀는데..

Tomcat plugin 은 JSP를 실행할 수 없는 모양입니다.

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>

---

Dependency를 추가해야 합니다.

        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
        </dependency>

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.3</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.study</groupId>
    <artifactId>springboot</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>
    <name>springboot</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>11</java.version>
    </properties>
    <dependencies>

        <!-- <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-oauth2-client</artifactId> </dependency> 
            <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> </dependency> -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-mustache</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
        </dependency>


        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>


    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

---

Dependency를 추가하고 jar 파일 다운로드 오류로 많은 시간을 허비했습니다.

Maven 의 문제인지, Eclipse의 문제인지.. ㅠ.ㅠ

The container 'Maven Dependencies' references non existing library 'C:\repository\org\apache\tomcat\embed\tomcat-embed-jasper\9.0.56\tomcat-embed-jasper-9.0.56.jar'

 

어찌 해결됐는지는 모르겠습니다.

계속해서 library는 다운로드 되지 않고, Dependency 오류가 발생했습니다.

해결을 위해 몸부림친 방법은 3가지 정도 입니다.

1. 프로젝트 폴더 > Run As > Maven Clean

2. 프로젝트 폴더 > Run As > Maven install

3. 프로젝트 폴더 > Maven > Update Project