Unable to locate the Javac Compiler 解决办法
在使用eclipse 运行 maven install的时候，出现这个错误：
[ERROR] Unable to locate the Javac Compiler in:
D:\Program Files\Java\jre6\..\lib\tools.jar
Please ensure you are using JDK 1.4 or above and
not a JRE (the com.sun.tools.javac.Main class is required).
In most cases you can change the location of your Java
installation by setting the JAVA_HOME environment variable.
解决方法：
window-->preferences-->java-->Installed JREs,编辑此项,改成jdk路径即可（之前报错是jre路径）,如下图