ubuntu中的chrome默认是没有java插件的，需要自己从网上下载。
首先从网上下载jdk或者jre：http://www.oracle.com/technetwork/java/javase/downloads/index.html
下载后解压，然后按照下图的命令进行插件的配置：
配置完成后在chrome刷新就可以显示java了。
参考：http://www.wikihow.com/Enable-Oracle-Java-in-Your-Web-Browsers-on-Ubuntu-Linux
Type/Copy/Paste: sudo mkdir /opt/google/chrome/plugins
this will create a directory called /opt/google/chrome/plugins
Type/Paste/Copy: cd /opt/google/chrome/plugins
this will change you into the google chrome plugins directory,make sure you are in this directory before you make the symbolic link
Type/Paste/Copy: sudo ln -s /usr/local/java/jre1.7.0_21/lib/i386/libnpjp2.so
this will create a symbolic link from the Java JRE( Java Runtime Environment ) plugin libnpjp2.so to your Google Chrome web browser