Linux-centos-7-64 bit: 1, install Java environment

In general, we will have to uninstall the Linux openjdk, and then install the Sun's JDK.

Start the terminal (run in the virtual machine)

First check to see if the Linux-brought JDK is installed.

Enter the following command to view the installed Java version information.

java -version

Enter the following command to view the information for the JDK.

rpm -qa|grep java

Uninstall the already installed Java, as shown in. (Note: The TAB key can be added, sometimes the package name will be abbreviated, do not worry about spelling mistakes)

yum -y remove java-1.7.0-openjdk-1.7.0.75-2.5.4.2.el7_0.x

Removal success

Uninstall the other one, as shown in.

-y remove tzdata-java-2015a-1.el7.noarch

Delete Complete

Next, install the Sun's JDK GZ format

Official website: http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html

The WINSCP tool is created directly from a remote connection or can be created from the command line

Create a share under/mnt Currently, you can view all the files in the directory by ls-a the various resource files.

-a

Create a Java directory under/usr/local to install the Java program in this directory, and enter the following command:

mkdir /usr/local/java

Copy the JDK file to the/usr/local/java directory and view it and enter the following command:

 cp jdk-8u91-linux-x64.gz /usr/local/java/ cd /usr/local-a

Unzip the file to the current directory and enter the following command:

-xzvf jdk-8u91-linux-x64.gz  

After decompression, in the/usr/local/java directory will generate a new directory jdk1.8.0_91, which is stored in the extracted files.

For ease of Setup later, we have renamed the directory jdk1.8.0_91 to jdk-1.8 and entered the following command:

mv jdk1.8.0_91 jdk-1.8  

Or, if the file you downloaded is in RPM format, replace it with the following command at the tar command above, and the other steps will be the same.

-ivh jdk-8u91-linux-x64.rpm  

Finally, the environment variable is set.

Enter the configuration file by entering the following command.

vi /etc/profile

Enter the configuration file, as shown, to remove the first row in the red box and change the configuration information to the following three lines.

export JAVA_HOME=/usr/local/java/jdk-1.8export PATH=$JAVA_HOME/bin:$PATHexport CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar

Then press the ESC key to end: wq! Save exit (remember to add a colon before)
Preparation:
"Colon", or ":" (without double quotes), a colon appears below, waiting for the input command
W:write, writing
Q:quit, exit
: wq! Save and exit
: Q Direct exit (Prerequisite: Document not changed)
: q! Do not save direct exit
:! Forced exit (not recommended)

Let the environment variable take effect.

Execute the configuration file so that it takes effect immediately and enter the following command:

source /etc/profile

To verify that the installation was successful, enter the following command:

java -version

(if command not found is displayed (commands not found) indicates that there is no Java-based soft link, see below)

Create a soft link to Java in the/sbin directory

At this point we enter the Java command in the shell, we will prompt the Java command is not found in/usr/bin, because we have not

$JAVA _home/bin/java to create a soft link in the/sbin directory

Create a soft link command to the/sbin/java directory

ln -s /usr/local/java/jdk-1.8/bin/java /sbin/java

As indicated by the completion

Report:
Running java-version without the relevant version information, the following error occurred:

DL failure on line 685error:failed/usr/local/jdk-1.8/jre/lib/i386/client/libjvm.so, because/usr/local/jdk-1.8/jre/ Lib/i386/client/libjvm.so:cannot Restore segment prot after Reloc:permission denied

Later through the query, it is the problem of SELinux setup.

The solution is as follows:

1. Open/etc/selinux/config
2. Change Selinux=enforcing to Selinux=disabled
3. Restart Linux

Run the first Java program.

Create a new Helloworld.java file as shown in.

Edit the file as shown in.

Save the file, compile and run as shown in.

Run successfully!

Linux-centos-7-64 bit: 1, install Java environment