Java Maven - 对于工件，版本不能为空
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Maven - for artifact the version cannot be empty
提问by jublikon
Problem:I am using maven and suddenly got some errors:
问题：我正在使用 maven，突然出现一些错误：
For artifact {org.springframework.boot:spring-boot-starter-data-jpa:null:jar}: The version cannot be empty. (org.apache.maven.plugins:maven-resources-plugin:2.6:resources:default-resources:process-resources)
org.apache.maven.artifact.InvalidArtifactRTException: For artifact {org.springframework.boot:spring-boot-starter-data-jpa:null:jar}: The version cannot be empty.
at org.apache.maven.artifact.DefaultArtifact.validateIdentity(DefaultArtifact.java:148)
at org.apache.maven.artifact.DefaultArtifact.<init>(DefaultArtifact.java:123)
at org.apache.maven.artifact.factory.DefaultArtifactFactory.createArtifact(DefaultArtifactFactory.java:157)
at org.apache.maven.artifact.factory.DefaultArtifactFactory.createDependencyArtifact(DefaultArtifactFactory.java:57)
at org.apache.maven.project.artifact.MavenMetadataSource.createDependencyArtifact(MavenMetadataSource.java:328)
at org.apache.maven.project.artifact.MavenMetadataSource.createArtifacts(MavenMetadataSource.java:503)
at org.apache.maven.lifecycle.internal.DefaultProjectArtifactFactory.createArtifacts(DefaultProjectArtifactFactory.java:50)
at org.apache.maven.lifecycle.internal.LifecycleDependencyResolver.resolveProjectDependencies(LifecycleDependencyResolver.java:119)
at org.apache.maven.lifecycle.internal.MojoExecutor.ensureDependenciesAreResolved(MojoExecutor.java:245)
at org.eclipse.m2e.core.internal.embedder.MavenImpl.execute(MavenImpl.java:330)
at org.eclipse.m2e.core.internal.embedder.MavenImpl.call(MavenImpl.java:1362)
at org.eclipse.m2e.core.internal.embedder.MavenImpl.call(MavenImpl.java:1)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.executeBare(MavenExecutionContext.java:176)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.execute(MavenExecutionContext.java:112)
at org.eclipse.m2e.core.internal.embedder.MavenImpl.execute(MavenImpl.java:1360)
at org.eclipse.m2e.core.project.configurator.MojoExecutionBuildParticipant.build(MojoExecutionBuildParticipant.java:52)
at org.eclipse.m2e.core.internal.builder.MavenBuilderImpl.build(MavenBuilderImpl.java:137)
at org.eclipse.m2e.core.internal.builder.MavenBuilder.method(MavenBuilder.java:172)
at org.eclipse.m2e.core.internal.builder.MavenBuilder.method(MavenBuilder.java:1)
at org.eclipse.m2e.core.internal.builder.MavenBuilder$BuildMethod.call(MavenBuilder.java:115)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.executeBare(MavenExecutionContext.java:176)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.execute(MavenExecutionContext.java:112)
at org.eclipse.m2e.core.internal.builder.MavenBuilder$BuildMethod.call(MavenBuilder.java:105)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.executeBare(MavenExecutionContext.java:176)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.execute(MavenExecutionContext.java:151)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.execute(MavenExecutionContext.java:99)
at org.eclipse.m2e.core.internal.builder.MavenBuilder$BuildMethod.execute(MavenBuilder.java:86)
at org.eclipse.m2e.core.internal.builder.MavenBuilder.build(MavenBuilder.java:200)
at org.eclipse.core.internal.events.BuildManager.run(BuildManager.java:735)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:206)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:246)
at org.eclipse.core.internal.events.BuildManager.run(BuildManager.java:301)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:304)
at org.eclipse.core.internal.events.BuildManager.basicBuildLoop(BuildManager.java:360)
at org.eclipse.core.internal.events.BuildManager.build(BuildManager.java:383)
at org.eclipse.core.internal.events.AutoBuildJob.doBuild(AutoBuildJob.java:144)
at org.eclipse.core.internal.events.AutoBuildJob.run(AutoBuildJob.java:235)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)
So I have added the artifact version <version>1.3.5.RELEASE</version>to spring-boot-starter-data-jpa. Unfortunately I still get the same issue. I have even cleanded the cache of maven.
maven -> updateproject did not help
and project -> cleandid neither help
所以我<version>1.3.5.RELEASE</version>在 spring-boot-starter-data-jpa 中添加了神器版本。不幸的是，我仍然遇到同样的问题。我什至清理了 maven 的缓存。
maven -> update项目没有帮助，project -> clean也没有帮助
Question:What else could I have done wrong?
问题：我还能做错什么？
pom.xml
pom.xml
<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>SpringDataDemo</groupId>
<artifactId>SpringDataDemo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.5.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<plugin>
<artifactId>maven-war-plugin</artifactId>
<version>2.6</version>
<configuration>
<warSourceDirectory>WebContent</warSourceDirectory>
<failOnMissingWebXml>false</failOnMissingWebXml>
</configuration>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>spring-releases</id>
<name>Spring Releases</name>
<url>https://repo.spring.io/libs-release</url>
</repository>
<repository>
<id>org.jboss.repository.releases</id>
<name>JBoss Maven Release Repository</name>
<url>https://repository.jboss.org/nexus/content/repositories/releases</url>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-releases</id>
<name>Spring Releases</name>
<url>https://repo.spring.io/libs-release</url>
</pluginRepository>
</pluginRepositories>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
<version>1.3.5.RELEASE</version>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<version>1.4.192</version>
</dependency>
</dependencies>
</project>
Eclipse marks weird lines red if it really is an issue of version numbers:
如果确实是版本号问题，Eclipse 会将奇怪的线条标记为红色：
采纳答案by Xtreme Biker
You need to inherit from Spring Boot's parent POM:
您需要从 Spring Boot 的父 POM 继承：
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.3.5.RELEASE</version>
</parent>
This parent POM declares lots of dependency versions for artifacts you might use on your projects, that way you don't need to specify it yourself.
这个父 POM 为您可能在项目中使用的工件声明了许多依赖版本，这样您就不需要自己指定它。
From the docs:
从文档：
Each release of Spring Boot provides a curated list of dependencies it supports. In practice, you do not need to provide a version for any of these dependencies in your build configuration as Spring Boot is managing that for you. When you upgrade Spring Boot itself, these dependencies will be upgraded as well in a consistent way.
Spring Boot 的每个版本都提供了它支持的依赖项的精选列表。实际上，您不需要在构建配置中为任何这些依赖项提供版本，因为 Spring Boot 会为您管理它。当您升级 Spring Boot 本身时，这些依赖项也会以一致的方式升级。
See also:
也可以看看：
回答by ernest_k
The version is missing in the following plugin declaration:
以下插件声明中缺少该版本：
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
Just add the version:
只需添加版本：
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<version>1.3.5.RELEASE</version>
</plugin>
