<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.5.1</version>
<configuration>
<source>1.7</source>
<target>1.7</target>
</configuration>
</plugin>

此插件是设置编译的版本，跟jdk一致，缺省值为1.5，如果配置不对会导致编译错误