1, to the Sun's official website download
If the path cannot be found, please Baidu "Oracle technology Networkjavajava SEDownloads"
Select Accept License and select the JDK download that fits your model.
2, unzip the file, modify the filename
$ sudo mkdir/usr/lib/jvm$ sudo tar zxvf jdk-7u21-linux-i586.tar.gz-c/usr/lib/jvm$ cd/usr/lib/jvm$ sudo mv jdk1.7.0_21 Java
3. Add Environment variables
$ sudo vim ~/.BASHRC
Add the following:
Export Java_home=/usr/lib/jvm/java export JRE_HOME=${JAVA_HOME}/JRE export classpath=.:${java_home}/lib:${jre_ Home}/lib export Path=${java_home}/bin: $PATH
4. Configuring the default JDK version
sudo update-alternatives--install/usr/bin/java java/usr/lib/jvm/java/bin/java sudo update-alternatives-- Install/usr/bin/javac javac/usr/lib/jvm/java/bin/javac sudo update-alternatives--install/usr/bin/jar jar/ Usr/lib/jvm/java/bin/jar sudo update-alternatives--install/usr/bin/javah javah/usr/lib/jvm/java/bin/javah sudo update-alternatives--install/usr/bin/javap javap/usr/lib/jvm/java/bin/javap 300
And then execute
sudo update-alternatives--config java
If you first install the JDK, you will be prompted
There is only one alternative in link Group Java (providing/usr/bin/java):/usr/lib/jvm/java/bin/java no configuration required.
For non-initial installation, there will be different versions of the JDK option.
Because I am installing Ubuntu 14.04 in a virtual machine, OPENJDK is not installed by default, so there is no need to select the JDK version. If the Ubuntu version is installed on a physical machine, there are several candidates that can be used to replace Java (providing/usr/bin/java).
Select the path priority state------------------------------------------------------------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/bin/java 300 manual mode \# to maintain current value Press ENTER, or type the number of your choice: 2update-alternatives: Use/usr/lib/jvm/java-8/bin/java to provide/usr/bin/java (Java) in manual mode.
5. Testing
$ Java-versionjava Version "1.7.0_21" Java (tm) SE Runtime Environment (build 1.7.0_21-b11) Java HotSpot (tm) Server VM (Buil D 23.21-B01, Mixed mode)
Ubuntu 14.04 Installation JDK 8,ubuntu14.04