使用alternatives命令完成，必须具有root权限。
alternative命令介绍
alternatives version 1.3.30.2 - Copyright (C) 2001 Red Hat, Inc.
This may be freely redistributed under the terms of the GNU Public License.usage: alternatives --install <link> <name> <path> <priority> [--initscript <service>] [--slave <link> <name> <path>]* alternatives --remove <name> <path> alternatives --auto <name> alternatives --config <name> alternatives --display <name> alternatives --set <name> <path>看当前java版本：-bash-3.2$ /usr/sbin/alternatives --display java
java - status is auto. link currently points to /usr/lib/jvm/jre-1.6.0-sun/bin/java/usr/lib/jvm/jre-1.6.0-sun/bin/java - priority 1603 slave javaws_bin: /usr/lib/jvm/jre-1.6.0-sun/bin/javaws slave jcontrol: /usr/lib/jvm/jre-1.6.0-sun/bin/jcontrol slave keytool: /usr/lib/jvm/jre-1.6.0-sun/bin/keytool slave orbd: /usr/lib/jvm/jre-1.6.0-sun/bin/orbd slave pack200: /usr/lib/jvm/jre-1.6.0-sun/bin/pack200 slave policytool: /usr/lib/jvm/jre-1.6.0-sun/bin/policytool slave rmid: /usr/lib/jvm/jre-1.6.0-sun/bin/rmid slave rmiregistry: /usr/lib/jvm/jre-1.6.0-sun/bin/rmiregistry slave servertool: /usr/lib/jvm/jre-1.6.0-sun/bin/servertool slave tnameserv: /usr/lib/jvm/jre-1.6.0-sun/bin/tnameserv slave unpack200: /usr/lib/jvm/jre-1.6.0-sun/bin/unpack200 slave jre_exports: /usr/lib/jvm-exports/jre-1.6.0-sun slave jre: /usr/lib/jvm/jre-1.6.0-sun slave javaws: /usr/lib/jvm/jre-1.6.0-sun/javaws slave java.1: /usr/share/man/man1/java-java-1.6.0-sun-compat.1 slave javaws.1: /usr/share/man/man1/javaws-java-1.6.0-sun-compat.1 slave keytool.1: /usr/share/man/man1/keytool-java-1.6.0-sun-compat.1 slave orbd.1: /usr/share/man/man1/orbd-java-1.6.0-sun-compat.1 slave pack200.1: /usr/share/man/man1/pack200-java-1.6.0-sun-compat.1 slave policytool.1: /usr/share/man/man1/policytool-java-1.6.0-sun-compat.1 slave rmid.1: /usr/share/man/man1/rmid-java-1.6.0-sun-compat.1 slave rmiregistry.1: /usr/share/man/man1/rmiregistry-java-1.6.0-sun-compat.1 slave servertool.1: /usr/share/man/man1/servertool-java-1.6.0-sun-compat.1 slave tnameserv.1: /usr/share/man/man1/tnameserv-java-1.6.0-sun-compat.1 slave unpack200.1: /usr/share/man/man1/unpack200-java-1.6.0-sun-compat.1/usr/lib/jvm/jre-1.4.2-gcj/bin/java - priority 1420 slave javaws_bin: (null) slave jcontrol: (null) slave keytool: /usr/lib/jvm/jre-1.4.2-gcj/bin/keytool slave orbd: (null) slave pack200: (null) slave policytool: (null) slave rmid: (null) slave rmiregistry: /usr/lib/jvm/jre-1.4.2-gcj/bin/rmiregistry slave servertool: (null) slave tnameserv: (null) slave unpack200: (null) slave jre_exports: /usr/lib/jvm-exports/jre-1.4.2-gcj slave jre: /usr/lib/jvm/jre-1.4.2-gcj slave javaws: (null) slave java.1: (null) slave javaws.1: (null) slave keytool.1: (null) slave orbd.1: (null) slave pack200.1: (null) slave policytool.1: (null) slave rmid.1: (null) slave rmiregistry.1: (null) slave servertool.1: (null) slave tnameserv.1: (null) slave unpack200.1: (null)Current `best' version is /usr/lib/jvm/jre-1.6.0-sun/bin/java.安装新版本：-bash-3.2$ /usr/sbin/alternatives --install /usr/bin/java java /home/bio/software/jdk1.6.0_06-x86_64/bin/java 1664
-bash-3.2$ /usr/sbin/alternatives --install /usr/bin/javac javac /home/bio/software/jdk1.6.0_06-x86_64/bin/javac 1664[root@localhost sbin]# ./alternatives --config java[root@localhost sbin]# ./alternatives --config javac
分别选择，搞定。