Centos7 Installing the JDK

1, uninstall the system's own OPENJDK and related Java files

(1) Check the OPENJDK version information that comes with the system, and in the command window, type: java-version

(2) Rpm-qa | grep java

RPM Management Suite
-qa use Inquiry mode to query all packages

In the above file:
The following few can be removed
Java-1.7.0-openjdk-1.7.0.151-2.6.11.1.el7_4.x86_64
Java-1.8.0-openjdk-headless-1.8.0.151-1.b12.el7_4.x86_64
Java-1.8.0-openjdk-1.8.0.151-1.b12.el7_4.x86_64
Java-1.7.0-openjdk-headless-1.7.0.151-2.6.11.1.el7_4.x86_64

Noarch files can not be deleted
Python-javapackages-3.4.1-11.el7.noarch
Tzdata-java-2017c-1.el7.noarch
Javapackages-tools-3.4.1-11.el7.noarch

(3) Complete the delete file command in the Command window type (note the need to switch to the root user, otherwise it will delete the failure):

RPM-E--nodeps java-1.7.0-openjdk-1.7.0.151-2.6.11.1.el7_4.x86_64
RPM-E--nodeps java-1.8.0-openjdk-headless-1.8.0.151-1.b12.el7_4.x86_64
RPM-E--nodeps java-1.8.0-openjdk-1.8.0.151-1.b12.el7_4.x86_64
RPM-E--nodeps java-1.7.0-openjdk-headless-1.7.0.151-2.6.11.1.el7_4.x86_64

Command Description:
RPM Management Suite
-e Delete the specified package
--nodeps does not verify the correlation of the suite files

(4) Check whether it has been deleted successfully
In the Command window, type: java-version

The delegate has been deleted successfully.

2. Download JDK

(1) Historical version: Http://www.oracle.com/technetwork/java/javase/archive-139210.html
I was in the Centos7 browser to download the JDK:

Download by browser will be downloaded by default to the current user's download directory,
For example, the current login user is root, then the download location is "/root/Download/jdk-8u144-linux-x64.tar.gz":

Download Complete:

(2) You can see the specific path of the downloaded package:

Find/-name ". tar.gz"

(3) Back up the file to software and copy it to/usr/java:

(4) Unzip the JDK under/usr/java
TAR-ZXVF jdk-8u144-linux-x64.tar.gz

(5) Remove JDK

RM-RF jdk-8u144-linux-x64.tar.gz

4. Configuring the JDK environment variables

(1) Editing global variables
Vi/etc/profile

Enter Insert State:
Paste the following on the last line of the text:
Note that java_home=/usr/java/jdk1.8.0_144 is your own directory.

"Note": CentOS6 above is javahome,centos7 {java_home}

(2) Allow the environment variable you just set to take effect and check if the installation was successful

Immediate effect: Source/etc/profile

View Java version: Java-version

Centos7 Installing the JDK