Docker下在编译android环境时，java -version 命令明明能够正确表示java已经安装成功，环境设置正确。但是，在编译android时，检查java版本却通不过去：提示/bin/bash: java: command not found 问题，
软链接方法解决
sudo ln -s /jdk1.6.0_21/bin/jar /bin/jar
sudo ln -s /jdk1.6.0_21/bin/java /bin/java
sudo ln -s /jdk1.6.0_21/bin/javac /bin/javac
sudo ln -s /jdk1.6.0_21/bin/javah /bin/javah
sudo ln -s /jdk1.6.0_21/bin/javadoc /bin/javadoc