maven设置默认JDK版本

1. 安装目录下的conf/setting.xml中profiles标签下  
2. 
   
3. <profile>  
4.     <id>jdk-1.7</id>  
5.     <activation>  
6.         <activeByDefault>true</activeByDefault>  
7.         <jdk>1.7</jdk>  
8.     </activation>  
9.     <properties>  
10.         <maven.compiler.source>1.7</maven.compiler.source>  
11.         <maven.compiler.target>1.7</maven.compiler.target>  
12.         <maven.compiler.compilerVersion>1.7</maven.compiler.compilerVersion>  
13.     </properties>   
14. </profile>