maven在eclipse中的问题

1. Unrecognised tag
   问题
   因为我使用本地代理仓库，因此settings.xml设置以下：

   <profiles>
   <profile>
   <id>nexus</id>
   <repositories>
   <repository>
   <id>nexus</id>
   <name>Nexus</name>
   <url>http://localhost:8081/nexus/content/groups/public</url>
   <releases><enabled>true</enabled></releases>
   <snapshots><enabled>true</enabled></snapshots>
   </repository>
   </repositories>
   <pluginRepositories>
   <pluginRepository>
   <id>nexus</id>
   <name>Nexus</name> 
   <url>http://localhost:8081/nexus/content/groups/public</url>
   <releases><enabled>true</enabled></releases>
   <snapshots><enabled>true</enabled></snapshots> 
   </pluginRepository> 
   </pluginRepositories>
   </profile> 
   <!--激活配置-->
   <activeProfiles>
   <activeProfile>nexus</activeProfile>
   </activeProfiles>
   </profiles>

   但在Maven编译时报了以下异常：

   [WARNING] Some problems were encountered while building the effective settings
   [WARNING] Unrecognised tag: 'activeProfiles' (position: START_TAG seen ...\n\t... @269:18) @ C:\Documents and Settings\Administrator.ZQFGROUP.000\.m2\settings.xml, line 269, column 18
   [WARNING]

   解决
   这是由于错把activeProfiles配置到了profiles节点里了，应该把activeProfiles移到profiles以外，更多settings.xml配置信息请参考这里。

2. No goals
   问题
   Eclipse安装了Maven插件后，在项目的pom.xml上右键能看到以下：
   
   而我自做聪明地认为:Maven build 与 mvn compile 是等价的，因而我再点击"Maven build..."以后，“Goals”是空的，如：
   
   因而就报了这样的错误：

   [ERROR] No goals have been specified for this build. You must specify a valid lifecycle phase or a goal in the format:or:[:]:. Available lifecycle phases are: validate, initialize, generate-sources, process-sources, generate-resources, process-resources, compile, process-classes, generate-test-sources, process-test-sources, generate-test-resources, process-test-resources, test-compile, process-test-classes, test, prepare-package, package, pre-integration-test, integration-test, post-integration-test, verify, install, deploy, pre-site, site, post-site, site-deploy, pre-clean, clean, post-clean. -> [Help 1]

   解决
   解决方法至少有两种：

• 再点击"Maven build..."以后，输入你要执行的“Goals”，如compile,clean,test等等;

• 在pom.xml中配置默认的Goal，如：

  <build>
  <defaultGoal>clean</defaultGoal>
  </build>

  做为project的子节点。

3.  not a JRE
   问题
   在使用pom.xml配置默认Goal的时，若是默认的Goal为clean就没问题，但若是是如:

   就会报错误：

   [ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:2.3.2:compile (default-compile) on project Demo: Compilation failure
   [ERROR] Unable to locate the Javac Compiler in:
   [ERROR] C:\Program Files\Java\jre7\..\lib\tools.jar
   [ERROR] Please ensure you are using JDK 1.4 or above and
   [ERROR] not a JRE (the com.sun.tools.javac.Main class is required).
   [ERROR] In most cases you can change the location of your Java
   [ERROR] installation by setting the JAVA_HOME environment variable.

   通过几番尝试，才发现并非多个Goal的问题，而是compile Goal的问题。但使用命令的"mvn compile"又是OK的。
   几经折腾才发现错误里说的很清楚：Please ensure you are using JDK 1.4 or above and not a JRE"，它须要的是JDK而不是JRE。我给的项目中使用的是公共JRE：
   
   解决
   修改Eclipse的配置，使用JDK：Eclipse->Window->Preferences->Java->Installed JREs
   
   Finish后，项目如：
   

4. system propery is not set

   错误：-Dmaven.multiModuleProjectDirectory system propery is not set.

   新建一个环境变量M2_HOME指向你的maven安装目录
   M2_HOME=D:\study\apache-maven-3.3.3
   而后在Window->Preference->Java->Installed JREs->Edit
   在Default VM arguments中设置
   -Dmaven.multiModuleProjectDirectory=$M2_HOME

5.      Launching New_configuration

项目上右击->Run/Debug Settings->删除 new_Configuration.

maven参考资料：

http://tangyanbo.iteye.com/category/220107

http://www.cnblogs.com/xing901022/p/4170248.html

http://blog.csdn.net/gebitan505/article/details/46234359