maven在eclipse中的問題

1. Unrecognised tag
   問題
   因爲我使用本地代理倉庫，因此settings.xml設置以下：

   <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編譯時報了以下異常：

   [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]

   解決
   這是由於錯把activeProfiles配置到了profiles節點裏了，應該把activeProfiles移到profiles以外，更多settings.xml配置信息請參考這裏。

2. No goals
   問題
   Eclipse安裝了Maven插件後，在項目的pom.xml上右鍵能看到以下：
   
   而我自做聰明地認爲:Maven build 與 mvn compile 是等價的，因而我再點擊"Maven build..."以後，「Goals」是空的，如：
   
   因而就報了這樣的錯誤：

   [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]

   解決
   解決方法至少有兩種：

• 再點擊"Maven build..."以後，輸入你要執行的「Goals」，如compile,clean,test等等;

• 在pom.xml中配置默認的Goal，如：

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

  做爲project的子節點。

3.  not a JRE
   問題
   在使用pom.xml配置默認Goal的時，若是默認的Goal爲clean就沒問題，但若是是如:

   就會報錯誤：

   [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.

   通過幾番嘗試，才發現並非多個Goal的問題，而是compile Goal的問題。但使用命令的"mvn compile"又是OK的。
   幾經折騰才發現錯誤裏說的很清楚：Please ensure you are using JDK 1.4 or above and not a JRE"，它須要的是JDK而不是JRE。我給的項目中使用的是公共JRE：
   
   解決
   修改Eclipse的配置，使用JDK：Eclipse->Window->Preferences->Java->Installed JREs
   
   Finish後，項目如：
   

4. system propery is not set

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

   新建一個環境變量M2_HOME指向你的maven安裝目錄
   M2_HOME=D:\study\apache-maven-3.3.3
   而後在Window->Preference->Java->Installed JREs->Edit
   在Default VM arguments中設置
   -Dmaven.multiModuleProjectDirectory=$M2_HOME

5.      Launching New_configuration

項目上右擊->Run/Debug Settings->刪除 new_Configuration.

maven參考資料：

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

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

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