https://www.digitalocean.com/community/tutorials/how-to-install-java-on-ubuntu-with-apt-get
安裝原生 default 的 JRE/JDK
這是較佳且容義的選擇,在 Ubuntu 12.04~ 會安裝 OpenJDK 6,而 Ubuntu 12.10+ 則會安裝 OpenJDK 7全程只需用 apt-get 安裝即可, 便利且穩定。
指令:
sudo apt-get update
sudo apt-get install default-jre
sudo apt-get install default-jdk
安裝 OpenJDK 7
指令:sudo apt-get install openjdk-7-jre
sudo apt-get install openjdk-7-jdk
安裝 Oracle JDK
前置工作:sudo apt-get install python-software-properties
sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
安裝Oracle JDK 6:
sudo apt-get install oracle-java-6-installer
安裝Oracle JDK 7:
sudo apt-get install oracle-java-7-installer
安裝Oracle JDK 8:
sudo apt-get install oracle-java-8-installer
管理 JAVA使用版本
設定 java 與 javacsudo update-alternatives --config java
sudo update-alternatives --config javac
設定 JAVA_HOME
vi /etc/environment
修改 JAVA_HOME="想採用的java path"
如: JAVA_HOME="/usr/lib/jvm/java-7-oracle"
原文如下:
This is the recommended and easiest option. This will install OpenJDK 6 on Ubuntu 12.04 and earlier and on 12.10+ it will install OpenJDK 7.Installing Java with
apt-get
is easy. First, update the package index:sudo apt-get update
Then, check if Java is not already installed:java -version
If it returns "The program java can be found in the following
packages", Java hasn't been installed yet, so execute the following
command:sudo apt-get install default-jre
This will install the Java Runtime Environment (JRE). If you instead
need the Java Development Kit (JDK), which is usually needed to compile
Java applications (for example Apache Ant, Apache Maven, Eclipse and IntelliJ IDEA execute the following command:sudo apt-get install default-jdk
That is everything that is needed to install Java. All other steps are optional and must only be executed when needed.
Installing OpenJDK 7 (optional)
To install OpenJDK 7, execute the following command:sudo apt-get install openjdk-7-jre
This will install the Java Runtime Environment (JRE). If you instead
need the Java Development Kit (JDK), execute the following command:sudo apt-get install openjdk-7-jdk
Installing Oracle JDK (optional)
The Oracle JDK is the official JDK; however, it is no longer provided by Oracle as a default installation for Ubuntu.You can still install it using apt-get. To install any version, first execute the following commands:
sudo apt-get install python-software-properties
sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
Then, depending on the version you want to install, execute one of the following commands:Oracle JDK 6
This is an old version but still in use.sudo apt-get install oracle-java6-installer
Oracle JDK 7
This is the latest stable version.sudo apt-get install oracle-java7-installer
Oracle JDK 8
This is a developer preview, the general release is scheduled for March 2014. This external article about Java 8 may help you to understand what it's all about.sudo apt-get install oracle-java8-installer
Managing Java (optional)
When there are multiple Java installations on your Droplet, the Java version to use as default can be chosen. To do this, execute the following command:sudo update-alternatives --config java
It will usually return something like this if you have 2 installations (if you have more, it will of course return more):There are 2 choices for the alternative java (providing /usr/bin/java).
Selection Path Priority Status
------------------------------------------------------------
* 0 /usr/lib/jvm/java-7-oracle/jre/bin/java 1062 auto mode
1 /usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java 1061 manual mode
2 /usr/lib/jvm/java-7-oracle/jre/bin/java 1062 manual mode
Press enter to keep the current choice[*], or type selection number:
You can now choose the number to use as default. This can also be done for the Java compiler (javac
):sudo update-alternatives --config javac
It is the same selection screen as the previous command and should be
used in the same way. This command can be executed for all other
commands which have different installations. In Java, this includes but
is not limited to: keytool
, javadoc
and jarsigner
.Setting the "JAVA_HOME" environment variable
To set theJAVA_HOME
environment variable, which is needed for some programs, first find out the path of your Java installation:sudo update-alternatives --config java
It returns something like:There are 2 choices for the alternative java (providing /usr/bin/java).
Selection Path Priority Status
------------------------------------------------------------
* 0 /usr/lib/jvm/java-7-oracle/jre/bin/java 1062 auto mode
1 /usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java 1061 manual mode
2 /usr/lib/jvm/java-7-oracle/jre/bin/java 1062 manual mode
Press enter to keep the current choice[*], or type selection number:
The path of the installation is for each:/usr/lib/jvm/java-7-oracle
/usr/lib/jvm/java-6-openjdk-amd64
/usr/lib/jvm/java-7-oracle
/etc/environment
:sudo nano /etc/environment
In this file, add the following line (replacing YOUR_PATH by the just copied path):JAVA_HOME="YOUR_PATH"
That should be enough to set the environment variable. Now reload this file:source /etc/environment
Test it by executing:echo $JAVA_HOME
If it returns the just set path, the environment variable has been
set successfully. If it doesn't, please make sure you followed all steps
correctly.文章來源:
https://www.digitalocean.com/community/tutorials/how-to-install-java-on-ubuntu-with-apt-get
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