<dependency>
        <groupId>com.test</groupId>
        <artifactId>fooLib</artifactId>
        <version>1.0-SNAPSHOT</version>
    </dependency>
    ....
    <repository>
        <id>in-project</id>
        <snapshots>
            <updatePolicy>always</updatePolicy>
            <enabled>true</enabled>
        </snapshots>
        <name>In Project Repo</name>
        <url>file://${project.basedir}/libRepo</url>
    </repository>

问题是当我更换libRepo中的jar(没有更新版本号,因为它只是另一个快照)没有使用这个更新的jar(而是使用.m2目录的旧版本),即使对于mvn -U clean install
如何让maven更新这个jar？

编辑：
根据What exactly is a Maven Snapshot and why do we need it? maven将尝试找到永远不会发布的SNAPSHOT依赖版本,“即使在本地存储库中找到了这个库的版本”.我的设置有什么问题？

肮脏的解决方案：
根据Maven 2 assembly with dependencies: jar under scope “system” not included的答案,我的原始解决方案的扩展似乎工作：

<plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-install-plugin</artifactId>
            <executions>
                <execution>
                    <id>hack-binary</id>
                    <phase>validate</phase>
                    <configuration>
                        <file>${repo.path.to.jar}</file>
                        <repositoryLayout>default</repositoryLayout>
                        <groupId>com.test</groupId>
                        <artifactId>fooLib</artifactId>
                        <version>1.0-SNAPSHOT</version>
                        <packaging>jar</packaging>
                        <generatePom>true</generatePom>
                    </configuration>
                    <goals>
                        <goal>install-file</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>

正如对该解决方案的评论中所提到的,它不能单独工作,因此它与项目内存储库(当依赖在本地.m2存储库中不可用时工作)一起工作,而第二部分在每次构建期间刷新.m2.

然而,我仍然不清楚为什么普通的“SNAPSHOT”机制不起作用(即当前的脏解决方案也可以在没有SNAPSHOT的情况下工作,因为本地.m2 repo每次都被明确更新).有没有更干净的方式？

解决方案(基于Aaron的回答和讨论)：问题是我尝试使用install-file将文件安装到libRepo中.实际的解决方案是,如果库更新,请使用

mvn deploy:deploy-file -Dfile=fooLib.jar  -DgroupId=com.test \
    -DartifactId=fooLib -Dversion=1.0-SNAPSHOT -Dpackaging=jar \
    -Durl=file://..\libRepo -DrepositoryId=in-project

将其部署到回购.正确部署后,maven正确处理SNAPSHOT.

顺便提一下,为此目的在内部为快照分配了一个版本号：这样Maven就可以在内部注意到快照已经更新.

我建议改用system dependency.这样,实际的JAR将被添加到类路径中(没有任何复制或东西).您也不需要复制此方法的repo结构,它将清楚地传达您的意图.

[编辑]我知道Maven以不同的方式处理与范围系统的依赖关系.我不确定这是否有意义(如果它使用依赖项进行编译,它肯定可以用它来运行？)

在我看来,你有这些选择：

>使用deploy:deploy-file将依赖项安装到libRepo中,而不是自己复制它.这应该以这样的方式更新元数据：当您在真实项目上再次运行mvn install时,Maven将再次复制它.

请注意file：install不起作用.文件插件用于访问本地存储库,但您需要使用知道如何更新共享/服务器存储库的deploy插件.>将依赖项安装到本地存储库中;我建议你使用一个脚本,你可以包含在你的项目中.这样,您可以避免所有问题,并且可以轻松地在新机器上进行设置.>更改依赖项的版本号,但这很乏味,当依赖项的实际版本号发生更改时,您可能会遇到麻烦.>为您的公司设置本地仓库服务器并将依赖关系部署到该公司.这将需要几个小时,但a)您将获得所有依赖项的本地缓存,使您的初始构建更快,b)它将更快地为其他开发人员设置.

使用maven 2.2.1,突然间它无法解析maven-clean-plugin.真的,构建工具需要一个“干净”的插件是多么疯狂？

我尝试从另一台运行良好的机器同步我的.m2目录,并得到相同的结果.

taproot:~/$mvn clean package -DskipTests
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Building CRM Webapp
[INFO]    task-segment: [clean,package]
[INFO] ------------------------------------------------------------------------
Downloading: http://download.java.net/maven/2/org/apache/maven/plugins/maven-clean-plugin/2.2/maven-clean-plugin-2.2.pom
[INFO] Unable to find resource 'org.apache.maven.plugins:maven-clean-plugin:pom:2.2' in repository maven.java.net (http://download.java.net/maven/2)
Downloading: http://repo1.maven.org/maven2/org/apache/maven/plugins/maven-clean-plugin/2.2/maven-clean-plugin-2.2.pom
[WARNING] Unable to get resource 'org.apache.maven.plugins:maven-clean-plugin:pom:2.2' from repository central (http://repo1.maven.org/maven2): Specified destination directory cannot be created: /Users/armhold/.m2/repository/org/apache/maven/plugins/maven-clean-plugin/2.2
Downloading: http://repository.jboss.org/nexus/content/groups/public-jboss//org/apache/maven/plugins/maven-clean-plugin/2.2/maven-clean-plugin-2.2.pom
[INFO] Unable to find resource 'org.apache.maven.plugins:maven-clean-plugin:pom:2.2' in repository public jboss (http://repository.jboss.org/nexus/content/groups/public-jboss/)
Downloading: https://repository.jboss.org/nexus/content/repositories/releases//org/apache/maven/plugins/maven-clean-plugin/2.2/maven-clean-plugin-2.2.pom
[INFO] Unable to find resource 'org.apache.maven.plugins:maven-clean-plugin:pom:2.2' in repository jboss-my-rel (https://repository.jboss.org/nexus/content/repositories/releases/)
Downloading: http://repository.jboss.org/maven2//org/apache/maven/plugins/maven-clean-plugin/2.2/maven-clean-plugin-2.2.pom
[WARNING] Unable to get resource 'org.apache.maven.plugins:maven-clean-plugin:pom:2.2' from repository JBOSS (http://repository.jboss.org/maven2/): Specified destination directory cannot be created: /Users/armhold/.m2/repository/org/apache/maven/plugins/maven-clean-plugin/2.2
Downloading: http://repo1.maven.org/maven2/org/apache/maven/plugins/maven-clean-plugin/2.2/maven-clean-plugin-2.2.pom
[WARNING] Unable to get resource 'org.apache.maven.plugins:maven-clean-plugin:pom:2.2' from repository central (http://repo1.maven.org/maven2): Specified destination directory cannot be created: /Users/armhold/.m2/repository/org/apache/maven/plugins/maven-clean-plugin/2.2
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Error building POM (may not be this project's POM).


Project ID: org.apache.maven.plugins:maven-clean-plugin

Reason: POM 'org.apache.maven.plugins:maven-clean-plugin' not found in repository: Unable to download the artifact from any repository

  org.apache.maven.plugins:maven-clean-plugin:pom:2.2

from the specified remote repositories:
  jboss-my-rel (https://repository.jboss.org/nexus/content/repositories/releases/),central (http://repo1.maven.org/maven2),maven.java.net (http://download.java.net/maven/2),JBOSS (http://repository.jboss.org/maven2/),public jboss (http://repository.jboss.org/nexus/content/groups/public-jboss/)

 for project org.apache.maven.plugins:maven-clean-plugin

我的pom看起来像这样：

<repositories>
    <repository>
        <id>public jboss</id>
        <url>http://repository.jboss.org/nexus/content/groups/public-jboss/</url>
    </repository>

    <repository>
        <id>jboss-my-rel</id>
        <url>https://repository.jboss.org/nexus/content/repositories/releases/</url>
    </repository>

    <repository>
        <id>JBOSS</id>
        <name>JBoss Repository</name>
        <url>http://repository.jboss.org/maven2/</url>
    </repository>

</repositories>

<pluginRepositories>
    <pluginRepository>
        <id>maven.java.net</id>
        <name>Java.net Maven2 Repository</name>
        <url>http://download.java.net/maven/2</url>
    </pluginRepository>
</pluginRepositories>

Specified destination directory cannot be created:
 /Users/armhold/.m2/repository/org/apache/maven/plugins/maven-clean-plugin/2.2

你没有对该目录的写访问权(或者运行maven进程的用户没有)

任何想法为什么一直失败？
下面的堆栈跟踪

干杯,

mvn clean install -DskipTests -T 8C
[INFO] Scanning for projects...
Downloading: http://repo1.maven.org/maven2/org/apache/maven/wagon/wagon-webdav/1.0-beta-2/wagon-webdav-1.0-beta-2.pom
[ERROR] The build Could not read 1 project -> [Help 1]
[ERROR]   
[ERROR]   The project uk.co.three:Three:0.1 (/Users/***/Projects/three/Development/pom.xml) has 1 error
[ERROR]     Unresolveable build extension: Plugin org.apache.maven.wagon:wagon-webdav:1.0-beta-2 or one of its dependencies Could not be resolved: Failed to collect dependencies for org.apache.maven.wagon:wagon-webdav:jar:1.0-beta-2 (): Failed to read artifact descriptor for org.apache.maven.wagon:wagon-webdav:jar:1.0-beta-2: Could not transfer artifact org.apache.maven.wagon:wagon-webdav:pom:1.0-beta-2 from/to central (http://repo1.maven.org/maven2): Error transferring file: Connection refused -> [Help 2]
[ERROR] 
[ERROR] To see the full stack trace of the errors,re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions,please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/ProjectBuildingException
[ERROR] [Help 2] http://cwiki.apache.org/confluence/display/MAVEN/PluginResolutionException

如果是外部的,则必须在settings.xml中声明您的公司代理(在外部安装的conf文件夹中或在本地存储库中).

如果您使用嵌入式maven也可能是这种情况.然后,您必须在“嵌入式​​安装的全局设置”中提供设置文件.

如果您正在使用外部maven安装,您还可以在eclipse之外尝试命令行.

同

mvn -U ...

您可以强制maven查找最新的插件版本.