ubuntu指定默认jdk
将我要添加的jdk加入java菜单选项

update-alternatives --install /usr/bin/java java /usr/lib/jvm/java/jdk1.6.0_12/bin/java 300update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/java/jdk1.6.0_12/bin/javac 300

sudo update-alternatives --config java

?

There are 2 choices for the alternative java (providing /usr/bin/java).  Selection    Path                                      Priority   Status------------------------* 0            /usr/lib/jvm/java-6-openjdk/jre/bin/java   1061      auto mode  1            /usr/lib/jvm/java-6-openjdk/jre/bin/java   1061      manual mode  2            /usr/lib/jvm/java-6-sun/jre/bin/java       63        manual modePress enter to keep the current choice[*], or type selection number: 2    

?

选择java-6-sun后，再输入java -version，就会显示Sun的JDK信息了