Ubuntu replaces the Java environment with the installed version of OPENJDK as Oracle's JDK

1. View the JDK version installed by the system

[email protected]: ~# java-version
Java Version "1.7.0_79"
OpenJDK Runtime Environment (IcedTea 2.5.5) (7U79-2.5.5-0UBUNTU1)
OpenJDK 64-bit Server VM (build 24.79-b02, Mixed mode)

2. Upload the JDK to the/OPT directory

[email protected]: ~# cd/opt
[email protected]:/opt# ls
Jdk-6u45-linux-x64.bin

3. Modify the permissions of the JDK

[email protected]:/opt# chmod +x Jdk-6u45-linux-x64.bin

4. Execute the JDK file

[email protected]:/opt#./jdk-6u45-linux-x64.bin

5. Check out the extracted directory

[email protected]:/opt# ls
jdk1.6.0_45 Jdk-6u45-linux-x64.bin

6. Create a soft link

[email protected]:/opt# ln-s Jdk1.6.0_45/java
[email protected]:/opt# ls
Java jdk1.6.0_45

7. Modify the environment variable configuration file

[email protected]:/opt# vim/etc/profile

#set Java Environment
Export Java_home=/opt/java
Export Jre_home=/opt/java
Export classpath==.: $CLASSPATH: $JAVA _home/lib: $JRE _home/lib
Export path= $PATH: $JAVA _home/bin: $JRE _home/bin

8. Let the configuration file take effect

[email protected]:/opt# source/etc/profile

9. View the Java version

[email protected]: ~# java-version
Java Version "1.7.0_79"
OpenJDK Runtime Environment (IcedTea 2.5.5) (7U79-2.5.5-0UBUNTU1)
OpenJDK 64-bit Server VM (build 24.79-b02, Mixed mode)

10. View the Java version of the new configuration

[email protected]: ~#/opt/java/bin/java-version
Java Version "1.6.0_45"
Java (TM) SE Runtime Environment (build 1.6.0_45-b06)
Java HotSpot (TM) 64-bit Server VM (build 20.45-b01, Mixed mode)

11. Create a link

[email protected]: ~# update-alternatives--install/usr/bin/java Java/opt/java/bin/java 300
[email protected]: ~# update-alternatives--install/usr/bin/javac Javac/opt/java/bin/javac 300
Update-alternatives:using/opt/java/bin/javac to Provide/usr/bin/javac (javac) in Auto mode

12. Configure the system default Java environment

[email protected]: ~# update-alternatives--config java
There is 2 choices for the alternative Java (Providing/usr/bin/java).

Selection Path Priority Status
------------------------------------------------------------
* 0/usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java 1071 Auto mode
1/opt/java/bin/java Manual Mode
2/usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java 1071 Manual Mode

Press ENTER to keep the current choice[*], or type selection number:1

[email protected]: ~# update-alternatives--config Javac
There is a alternative in link Group Javac (providing/usr/bin/javac):/opt/java/bin/javac
Nothing to configure.

13. See if it takes effect

[email protected]: ~# java-version
Java Version "1.6.0_45"
Java (TM) SE Runtime Environment (build 1.6.0_45-b06)
Java HotSpot (TM) 64-bit Server VM (build 20.45-b01, Mixed mode)

This article is from the "Cloud Life" blog, make sure to keep this source http://ovcer.blog.51cto.com/1145188/1652637

Ubuntu replaces the Java environment with the installed version of OPENJDK as Oracle's JDK