4.0.0
junit junit 4.0 jar test true groupId，artifactId和version这个三组合标示依赖的具体工程，而且这个依赖工程必须是maven中心包管理范围内的。如果碰上非开源包，maven支持不了这个包，那么则有三种方法处理：1.本地安装这个插件install plugin例如：
mvn install:install-file -Dfile=non-maven-proj.jar -DgroupId=some.group -DartifactId=non-maven-proj -Dversion=1
2.创建自己的Repositories并且部署这个包，使用类似上面的 [object Object]命令3.设置scope为system，并且指定系统路径，用于区分从同一个pom编译出来的但是内容不同的同名包，例如同一个工程编译出两个artifact，一个支持jdk1.5一个支持jdk1.4，那么就可以使用这个来命名为jdk15和jdk14来区分，它如果出现在包名中，那么它必须跟在版本号后。还有一种情况是将一个工程的一些次要artifact附到主要artifact中，就可以使用这个来区分，例如一个工程产生source，javadoc，class三种东西，那么就可以使用不同的classifier来分别标识这些东西 [object Object]，默认为jar，类型，常用如：jar，ejb-client，test-jar，可以设置plugins中的extensions值为true后在增加新类型，指定classpath，可以为：compile（默认的，compile scope在所有classpaths内有效，这些dependencies将会传播到项目中。provided：指示jdk或者某个容器可以提供他，它只在compilation和test的classpaths有效，而且不会传播的。runtime：指示这个dependency在编译过程是不必要的，但是执行需要，在test和runtime的classpaths有效，在compile的classpaths无效。test：指示这个dependency在一般程序运行是无效的，但是在test的compilation和execution是有效的，system则跟provided类似，但是这种dependency必须人工明确地制定。这种依赖不会在repository中查找。：只在dependency的scope声明为system的时候才有用除，否则，build的过程将会失败。路径必须是绝对的，所以最好使用property来声明机器的特定路径。：如果工程本身是一个dependency那么就标记为optional，例如X需要A，A需要B，那么X只需要optional的B，则B在X中就是optional声明的了：如果X需要A，A包含B依赖，那么X可以声明不要B依赖，只要在exclusions中声明exclusion。optional是不会install或者使用B，而exclusion是将B从依赖树中是删除。例如appfuse不想使用hibernate，但是appfuse是集成hibernate的，所以就排除掉： [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] org.appfuse [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] appfuse-hibernate [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] --> [object Object] [object Object] ... ... [object Object] [object Object] [object Object] project的描述工程的初始时间 [object Object] [object Object] [object Object] [object Object] Apache 2 [object Object] [object Object] [object Object] http://www.apache.org/licenses/LICENSE-2.0.txt [object Object] [object Object] [object Object] repo [object Object] [object Object] [object Object] A business-friendly OSS license [object Object]
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name, url and comments: are self explanatory, and have been encountered before in other capacities. The fourth license element is:
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distribution: This describes how the project may be legally distributed. The two stated methods are repo (they may be downloaded from a Maven repository) or manual (they must be manually installed).
-->
<organization>...</organization><!-- <organization> <name>Codehaus Mojo</name> <url>http://mojo.codehaus.org</url> </organization> 很多工程都受到某些组织运行，这里设置基本信息 --><developers>...</developers> <!--例如：一个开发者可以有多个roles，properties是 <developers> <developer> <id>eric</id> <name>Eric</name> <email>eredmond@codehaus.org</email> <url>http://eric.propellors.net</url> <organization>Codehaus</organization> <organizationUrl>http://mojo.codehaus.org</organizationUrl> <roles> <role>architect</role> <role>developer</role> </roles> <timezone>-6</timezone> <properties> <picUrl>http://tinyurl.com/prv4t</picUrl> </properties> </developer> </developers> --><contributors>...</contributors>
<!--跟developer差不多，只是contributors是副的工作人员，不过良好工程应该需要更多的contributors而不是developer，例如： <contributors> <contributor> <name>Noelle</name> <email>some.name@gmail.com</email> <url>http://noellemarie.com</url> <organization>Noelle Marie</organization> <organizationUrl>http://noellemarie.com</organizationUrl> <roles> <role>tester</role> </roles> <timezone>-5</timezone> <properties> <gtalk>some.name@gmail.com</gtalk> </properties> </contributor> </contributors> --><!-- Environment Settings --> <issueManagement>...</issueManagement> <!--定义defect tracking system缺陷跟踪系统，比如有（bugzilla,testtrack,clearquest等），例如： <issueManagement> <system>Bugzilla</system> <url>http://127.0.0.1/bugzilla/</url> </issueManagement> --><ciManagement>...</ciManagement>
<!--Continuous Integration Management：设置自动build系统，一些集成程序包括continuum,Cruise control等。例如： <ciManagement>
<system>continuum</system> <url>http://127.0.0.1:8080/continuum</url> <notifiers> <notifier> <type>mail</type> <sendOnError>true</sendOnError> <sendOnFailure>true</sendOnFailure> <sendOnSuccess>false</sendOnSuccess> <sendOnWarning>false</sendOnWarning> <configuration><address>continuum@127.0.0.1</address></configuration> </notifier> </notifiers> </ciManagement> maven捕获一些经常重发生的配置，在notifier元素里配置。A notifier is the manner in which people are notified of certain build statuses. In the following example, this POM is setting a notifier of type mail (meaning email), and configuring the email address to use on the specified triggers sendOnError,sendOnFailure, and not sendOnSuccess or sendOnWarning.
--><mailingLists>...</mailingLists>
<!--例如： <mailingLists> <mailingList> <name>User List</name> <subscribe>user-subscribe@127.0.0.1</subscribe> <unsubscribe>user-unsubscribe@127.0.0.1</unsubscribe> <post>user@127.0.0.1</post> <archive>http://127.0.0.1/user/</archive> <otherArchives> <otherArchive>http://base.google.com/base/1/127.0.0.1</otherArchive> </otherArchives> </mailingList> </mailingLists> 看不懂解释啊，照搬吧： -
subscribe,
unsubscribe: There elements specify the email addresses which are used for performing the relative actions To subscribe to the user list above, a user would send an email to user-subscribe@127.0.0.1.
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archive: This element specifies the url of the archive of old mailing list emails, if one exists. If there are mirrored archives, they can be specified under otherArchives.
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post: The email address which one would use in order to post to the mailing list. Note that not all mailing lists have the ability to post to (such as a build failure list).
--><scm>...</scm> <!--例如：
<scm> <connection>scm:svn:http://127.0.0.1/svn/my-project</connection> <developerConnection>scm:svn:https://127.0.0.1/svn/my-project</developerConnection> <tag>HEAD</tag> <url>http://127.0.0.1/websvn/my-project</url> </scm>connection, developerConnection: 都是连接字符串，其中后者是具有write权限的scm连接，常用的scm工具包括cvs与subversion，还有其他，url的字符串格式是：scm:[provider]:[provider_specific]，例如cvs的是scm:cvs:pserver:127.0.0.1:/cvs/root:my-projecttag：说明project所在的目录tag，默认是HEAD，表示根目录url：公开的可浏览repository --> <prerequisites>...</prerequisites>
<!--首要条件，如果不满足，maven会在事件开始之前失败，在pom4.0，唯一的首要条件是maven元素--><repositories>...</repositories> <!--要成为maven2的repository artifact，必须具有pom文件在$BASE_REPO/groupId/artifactId/version/artifactId-version.pomBASE_REPO可以是本地，也可以是远程的。repository元素就是声明那些去查找的repositories
默认的central Maven repository在； <repositories> <repository> <releases> <enabled>false</enabled> <updatePolicy>always</updatePolicy> <checksumPolicy>warn</checksumPolicy> </releases> <snapshots> <enabled>true</enabled> <updatePolicy>never</updatePolicy> <checksumPolicy>fail</checksumPolicy> </snapshots> <id>codehausSnapshots</id> <name>Codehaus Snapshots</name> <url>http://snapshots.maven.codehaus.org/maven2</url> <layout>default</layout> </repository> </repositories>release和snapshots：是artifact的两种policies，pom可以选择那种政策有效。enable：本别指定两种类型是否可用，true or falseupdatePolicy:说明更新发生的频率always 或者 never 或者 daily（默认的）或者 interval:X（X是分钟数）checksumPolicy：When Maven deploys files to the repository, it also deploys corresponding checksum files. Your options are to ignore, fail, orwarn on missing or incorrect checksums.layout：maven1.x与maven2有不同的layout，所以可以声明为default或者是legacy（遗留方式maven1.x）。 --> <pluginRepositories>...</pluginRepositories>
<!--与Repositories具有类似的结构，只是Repositories是dependencies的home，而这个是plugins 的home。--><distributionManagement>...</distributionManagement> <!--管理distribution和supporting files。downloadUrl：是其他项目为了抓取本项目的pom’s artifact而指定的url，就是说告诉pom upload的地址也就是别人可以下载的地址。status：这里的状态不要受到我们的设置，maven会自动设置project的状态，有效的值：none：没有 声明状态，pom默认的；converted：本project是管理员从原先的maven版本convert到maven2的；partner：以前叫 做synched，意思是与partner repository已经进行了同步；deployed：至今为止最经常的状态，意思是制品是从maven2 instance部署的，人工在命令行deploy的就会得到这个；verified：本制品已经经过验证，也就是已经定下来了最终版。repository：声明deploy过程中current project会如何变成repository，说明部署到repository的信息。 <repository> <uniqueVersion>false</uniqueVersion> <id>corp1</id> <name>Corporate Repository</name> <url>scp://repo1/maven2</url> <layout>default</layout> </repository> <snapshotRepository> <uniqueVersion>true</uniqueVersion> <id>propSnap</id> <name>Propellors Snapshots</name> <url>sftp://propellers.net/maven</url> <layout>legacy</layout> </snapshotRepository> id, name:：唯一性的id，和可读性的name uniqueVersion：指定是否产生一个唯一性的version number还是使用address里的其中version部分。true or false url：说明location和transport protocol layout：default或者legacy--><site><!---声明如何部署project‘s 的site和document-> <!--例如： <site> <id>mojo.website</id> <name>Mojo Website</name> <url>scp://beaver.codehaus.org/home/projects/mojo/public_html/</url> </site> 与上面repository的元素相同意思 -->Relocation： <!-- 说明工程的变更，在这里警告使用者当心工程被重命名了等信息。重新指定id和名称，并且写个message注明备注 <relocation> <groupId>org.apache</groupId> <artifactId>my-project</artifactId> <version>1.0</version> <message>We have moved the Project under Apache</message> </relocation> --><profiles>...</profiles> <!--pom4.0的一个新特性就是具有根据environment来修改设置的能力。
它包含可选的activation（profile的触发器）和一系列的changes。例如test过程可能会指向不同的数据库（相对最终的deployment）或者不同的dependencies或者不同的repositories，并且是根据不同的JDK来改变的。那么结构如下：
[object Object]<profiles> [object Object] [object Object] [object Object]<profile> [object Object] [object Object] [object Object] [object Object] [object Object]<id>test</id> [object Object] [object Object] [object Object] [object Object] [object Object]<activation>...</activation> [object Object] [object Object] [object Object] [object Object] [object Object]<build>...</build> [object Object] [object Object] [object Object] [object Object] [object Object]<modules>...</modules> [object Object] [object Object] [object Object] [object Object] [object Object]<repositories>...</repositories> [object Object] [object Object] [object Object] [object Object] [object Object]<pluginRepositories>...</pluginRepositories> [object Object] [object Object] [object Object] [object Object] [object Object]<dependencies>...</dependencies> [object Object] [object Object] [object Object] [object Object] [object Object]<reporting>...</reporting> [object Object] [object Object] [object Object] [object Object] [object Object]<dependencyManagement>...</dependencyManagement> [object Object] [object Object] [object Object] [object Object] [object Object]<distributionManagement>...</distributionManagement> [object Object] [object Object] [object Object]</profile> [object Object]</profiles> [object Object]： 触发这个profile的条件配置如下例：（只需要其中一个成立就可以激活profile，如果第一个条件满足了，那么后面就不会在进行匹配。 [object Object] [object Object] [object Object]<profile> [object Object] [object Object] [object Object] [object Object] [object Object]<id>test</id> [object Object] [object Object] [object Object] [object Object] [object Object]<activation> [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]<activeByDefault>false</activeByDefault> [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]<jdk>1.5</jdk> [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]<os> [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]<name>Windows XP</name> [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]<family>Windows</family> [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]<arch>x86</arch> [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]<version>5.1.2600</version> [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]</os> [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]<property> [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]<name>mavenVersion</name> [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]<value>2.0.3</value> [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]</property> [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]<file> [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]<exists>${basedir}/file2.properties</exists> [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]<missing>${basedir}/file1.properties</missing> [object Object] [object Object] [object Object] [object Object] [object Object] [object Object] [object Object]</file> [object Object] [object Object] [object Object] [object Object] [object Object]</activation> --> 激活profile的方法有多个：setting文件的activeProfile元素明确指定激活的profile的ID，在命令行上明确激活Profile用-P flag 参数 查看某个build会激活的profile列表可以用：mvn help:active-profiles </project>
本文转自yunlielai51CTO博客，原文链接：http://blog.51cto.com/4925054/1176256，如需转载请自行联系原作者