Installation OpenJDK1.8 & OracleJDK1.8 on CentOS7

---

Installation OpenJDK1.8:

1, check whether the current machine has a built-in JDK

rpm -qa |grep java
rpm -qa |grep jdk
rpm -qa |grep gcj

2, if not skip the installation steps, any uninstallation

rpm -qa | grep java | xargs rpm -e --nodeps

Step 3, yum update source

yum update -y 

4, search yum package

yum list java-1.8*   

5, the installation OpenJDK

yum install java-1.8.0-openjdk* -y

6. Verify that the installation was successful

java -version
返回信息如下，则说明安装成功：
openjdk version "1.8.0_161"
OpenJDK Runtime Environment (build 1.8.0_161-b14)
OpenJDK 64-Bit Server VM (build 25.161-b14, mixed mode)

7, other common questions:

If the command not foundcommand can not find it, then in addition to environmental issues, then you need to find the installation location OpenJDK will configure it to /etc/profilefile:

export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.161-3.b14.el6_9.x86_64
export JRE_HOME=${JAVA_HOME}/jre
export CLASSPATH=$CLASSPATH:.:${JAVA_HOME}/lib:${JAVA_HOME}/jre/lib
export PATH=${JAVA_HOME}/bin:${JAVA_HOME}/jre/bin:$PATH

After configuration is complete, click reload the file:

source /etc/profile

---

Installation OracleJDK1.8:

1, download OracleJDK1.8 & Upload

下载地址：
http://download.oracle.com/otn-pub/java/jdk/8u171-b11/512cd62ec5174c3487ac17c61aaa89e8/jdk-8u171-linux-x64.tar.gz

➜  Linux Soft scp jdk-8u171-linux-x64.tar.gz [email protected]:/opt
[email protected]'s password:
jdk-8u171-linux-x64.tar.gz

2, extract to/usr/

[root@centos-linux ~]# cd /opt/           
[root@centos-linux opt]# du -sm jdk-8u171-linux-x64.tar.gz 
183     jdk-8u171-linux-x64.tar.gz     
[root@centos-linux opt]# tar -xf jdk-8u171-linux-x64.tar.gz    
[root@centos-linux opt]# mv jdk                           
jdk1.8.0_171/               jdk-8u171-linux-x64.tar.gz    
[root@centos-linux opt]# mv jdk1.8.0_171 jdk         
jdk1.8.0_171/               jdk-8u171-linux-x64.tar.gz           
[root@centos-linux opt]# mv jdk1.8.0_171 jdk1.8  
[root@centos-linux opt]# mv jdk1.8/ /usr/
[root@centos-linux opt]# cd /usr/
[root@centos-linux usr]# ls
bin  etc  games  include  jdk1.8  lib  lib64  libexec  local  sbin  share  src  tmp
[root@centos-linux usr]# cd jdk1.8/        
[root@centos-linux jdk1.8]# pwd
/usr/jdk1.8

3, configure the environment variables

[root@centos-linux ~]# vim /etc/profile   

# 在/etc/profile文件中大约第54行添加如下内容

# Java Env
export JAVA_HOME=/usr/jdk1.8
export JRE_HOME=${JAVA_HOME}/jre
export CLASSPATH=$CLASSPATH:.:${JAVA_HOME}/lib:${JAVA_HOME}/jre/lib
export PATH=${JAVA_HOME}/bin:${JAVA_HOME}/jre/bin:$PATH  
  
[root@centos-linux ~]# source /etc/profile  

4. Verify

[root@centos-linux ~]# java -version  
java version "1.8.0_171"     
Java(TM) SE Runtime Environment (build 1.8.0_171-b11)    
Java HotSpot(TM) 64-Bit Server VM (build 25.171-b11, mixed mode)