How to configure custom JDK in CentOS7

Since the centos7-dvd image selected comes with open jdk, it needs to be uninstalled. First query the built-in jdk:

rpm -qa | grep java

There will be 7 things with java names. Delete the files with openjdk among them. The command is as follows:

rpm -e --nodeps java-1.8.0-openjdk-1.8.0.102-4.b14.el7.x86_64
rpm -e --nodeps java-1.8.0-openjdk-headless-1.8.0.102-4.b14.el7.x86_64
rpm -e --nodeps java-1.7.0-openjdk-headless-1.7.0.111-2.6.7.8.el7.x86_64
rpm -e --nodeps java-1.7.0-openjdk-1.7.0.111-2.6.7.8.el7.x86_64

Execute again rpm -qa | grep java command, there are only three left:

javapackages-tools-3.4.1-11.el7.noarch
tzdata-java-2016g-2.el7.noarch
python-javapackages-3.4.1-11.el7.noarch

Then install the jdk you need, first enter the local directory:

cd /usr/local/

in Create a folder under this directory and name it jdk to store jdk files. Download file:

// wget 地址
wget

Get the url by right-clicking -> copy the link address, and then execute the command. It feels so good and the download speed is so fast!

Then execute the command:

tar -zxvf jdk-8u131-linux-x64.tar.gz

The result is an error, the error message:

gzip: stdin: not in gzip format
tar: Child returned status 1
tar: Error is not recoverable: exiting now

After searching online for a long time, I finally found the solution. First, use the file command to view the real attributes of the file:

file jdk-8u131-linux-x64.tar.gz

Display the result:

[root@localhost jdk]# file jdk-8u131-linux-x64.tar.gz 
jdk-8u131-linux-x64.tar.gz: HTML document, ASCII text, with very long lines, with CRLF line terminators

It turns out that the downloaded web page (html) is what I said about a few hundred megabytes of stuff? It opens in seconds. Then you can only download it manually, and then execute the rz command, select the downloaded file and transfer it to the Linux virtual machine, and perform decompression:

tar -zxvf jdk-8u131-linux-x64.tar.gz

The decompressed file is:

drwxr-xr-x. 8 10 143 4096 3月  15 16:35 jdk1.8.0_131

Delete the compressed file (optional):

rm -f jdk-8u131-linux-x64.tar.gz

Configure environment variables:

vim /etc/profile

Enter i to enter edit mode and add environment variables at the end of the file:

export JAVA_HOME=/usr/local/jdk/jdk1.8.0_131
export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export PATH=$PATH:$JAVA_HOME/bin

Press the esc key and enter wq (save and exit).
After saving, make the newly configured environment take effect:

source /etc/profile

Check whether the jdk installation is complete:

java -version

Display the result:

[root@localhost jdk]# java -version
java version "1.8.0_131"
Java(TM) SE Runtime Environment (build 1.8.0_131-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.131-b11, mixed mode)

indicates that the configuration is successful.

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