Introduction to installing and configuring JDK under CentOS system

Preface

When it comes to JDK, we have to mention an old interview question:
JDK (Java Development Kit)
JRE (Java Runtime Environment)
JVM (Java Virtual Machine)

I bought an Alibaba Cloud server on Singles’ Day, and it has been gathering dust ever since. Today I had nothing to do, so I took it out to play with it!
I have to say, Alibaba’s business is really fast. As soon as I made the purchase, the Alibaba staff called me to promote some services. I just said “I’m a student” and the topic was immediately ended!

After connecting remotely, I found that the host name is long and ugly, so I changed it first!

View the current host name

hostname

Modify the host name

hostnamectl set-hostname hayden 

Restart the service

Modification completed

Check and uninstall OpenJDK

Check Java related information to see if the system comes with OpenJDK and related installation packages. If so, uninstall them first.

java -version

rpm -qa | grep java

// rpm (RedHat Package Manger): RedHat software management tool, a tool used for packaging and installation // -qa (query, all)
// grep (global search rgular expression (RE) and print out the line): is a powerful text search tool 

If you find that OpenJDK and installation packages are installed, first uninstall them in sequence

rpm -e --nodeps tzdata-java-2012c-1.el6.noarch

rpm -e --nodeps java-1.6.0-openjdk-1.6.0.0-1.45.1.11.1.el6.x86_64

// -e: Delete the specified package // --nodeps: Do not verify the interdependence of package files

Install JDK using the downloaded compressed package

Download the corresponding JDK version compressed package from Oracle official website to your local computer
Oracle - Java Downloads

Create a new java directory in the usr directory and use sftp to put the downloaded JDK compressed package into this directory

mkdir /usr/java
ll /usr 

Enter the java directory and unzip the JDK compressed package. After the unzipping is complete, you can choose whether to delete the compressed package based on your mood!

cd /usr/java
ll
tar -zxvf jdk-8u311-linux-x64.tar.gz
ls

JDK environment configuration

Edit the profile file, add the following configuration at the end of the file, save and exit

vim /etc/profile

export JAVA_HOME=/usr/java/jdk1.8.0_311 
export CLASSPATH=.:$JAVA_HOME/jre/lib/rt.jar:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar 
export PATH=$PATH:$JAVA_HOME/bin

vim / vi editor shortcuts

:set nu // Display line number G // Jump to the last line of text G$ // Jump to the last character of the last line gg // Jump to the first character of the first line 0 // Jump to the first character of the current line

Reload the /etc/profile file through the source command to make the configuration effective

source /etc/profile 

Test whether the configuration is successful

Enter the following command, and the following information is displayed, indicating that the configuration is successful

java -version 

Of course, there is more than one way to install JDK. You can also install JDK through yum and rpm commands, but the configuration method is the same, exposing the JDK related paths

Install JDK via yum command

Search for JDK installation packages

yum search java | grep jdk

Download JDK, the default path is: /usr/lib/jvm/

yum install java-1.8.0-openjdk.x86_64

Install JDK through rpm command

Download the rpm installation package

wget http://download.oracle.com/otn-pub/java/jdk/8u181-b13/96a7b8442fe848ef90c96a2fad6ed6d1/jdk-8u181-linux-x64.rpm?AuthParam=1534132498_e541d098d71f6243516fa69cd17eba60

Install JDK

rpm -ivh jdk-8u181-linux-x64.rpm?AuthParam=1534132498_e541d098d71f6243516fa69cd17eba60

This is the end of this article about installing and configuring JDK under CentOS system. For more relevant CentOS configuration JDK content, please search for previous articles on 123WORDPRESS.COM or continue to browse the following related articles. I hope everyone will support 123WORDPRESS.COM in the future!