在 CentOS 7 系统安装 Java 8

Installing Java 8 on CentOS 7

Step 1: Update

As a matter of best practice we’ll update before installing any new programs:

yum -y update

Step 2: Install Java 8

yum install java-1.8.0-openjdk

Step 3: Verify Java is Installed

java -version

Example Output:

java -version
openjdk version "1.8.0_191"
OpenJDK Runtime Environment (build 1.8.0_191-b12)
OpenJDK 64-Bit Server VM (build 25.191-b12, mixed mode)

Set Java’s Home Environment

Step 1: Find Java’s Path

Let’s set the JAVA_HOME variable, using the following command will give us a path so we can set the variable.

update-alternatives --config java

You’ll see a prompt to “Enter to keep the current selection[+], or type selection number:”, if you had multiple Java version you could set the default here, but all we need is the path of Java so we can exit pressing enter. The highlighted area is the path we will need to copy/paste into our .bash_profile file.

Selection    Command
-----------------------------------------------
*+ 1           java-1.8.0-openjdk.x86_64 (/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-1.el7_6.x86_64/jre/bin/java)</code?

Step 2: Setting Java’s Path in Your Environment

After copying your Java’s path, open the .bash_profile with your text editor.

vim .bash_profile

Export your Java path into the .bash_profile by adding the following to the bottom of the file. (Your path may look different from mine, and it’s not important that they vary.)

export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-1.el7_6.x86_64/jre/bin/java

Refresh the File:

source .bash_profile

When you use the JAVA_HOME variable you’ll now be able to see the path you set.

echo $JAVA_HOME

Example Output:

/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-1.el7_6.x86_64/jre/bin/java

参考资料：

https://www.liquidweb.com/kb/install-java-8-on-centos-7/