CentOS 7 configure Java language development environment#

Initial setting reference: http://blog.csdn.net/wh211212/article/details/52923673

Install JDK8

Install Java SE Development Kit 8 (JDK8) and build the Java environment

Download and install JDK 8
[ Ensure the latest version and source URL of the JDK on the Oracle download site]http://www.oracle.com/technetwork/java/javase/downloads/index.html

[ root@linuxprobe ~]# curl -L "http://download.oracle.com/otn-pub/java/jdk/8u121-b13/e9e7ea248e2c4826b92b3f075a80e441/jdk-8u121-linux-x64.rpm"-H "Cookie: oraclelicense=accept-securebackup-cookie"-H "Connection: keep-alive"-O
# Use yum or rpm to install jdk (here a yum is an example)
[ root@linuxprobe ~]# yum localinstall jdk-8u121-linux-x64.rpm -y
Loaded plugins: fastestmirror
Examining jdk-8u121-linux-x64.rpm:2000:jdk1.8.0_121-1.8.0_121-fcs.x86_64
Marking jdk-8u121-linux-x64.rpm to be installed
Resolving Dependencies
- - > Running transaction check
- - - > Package jdk1.8.0_121.x86_64 2000:1.8.0_121-fcs will be installed
- - > Finished Dependency Resolution

Dependencies Resolved

===============================================================================================================================================================================================================================================================================
 Package                                                         Arch                                                      Version                                                               Repository                                                               Size
===============================================================================================================================================================================================================================================================================
Installing:
 jdk1.8.0_121                                                    x86_64                                                    2000:1.8.0_121-fcs                                                    /jdk-8u121-linux-x64                                                    263 M

Transaction Summary
===============================================================================================================================================================================================================================================================================
Install  1 Package

Total size:263 M
Installed size:263 M
Downloading packages:
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
 Installing :2000:jdk1.8.0_121-1.8.0_121-fcs.x86_64                                                                                                                                                                                                                      1/1
Unpacking JAR files...
 tools.jar...
 plugin.jar...
 javaws.jar...
 deploy.jar...
 rt.jar...
 jsse.jar...
 charsets.jar...
 localedata.jar...
 Verifying  :2000:jdk1.8.0_121-1.8.0_121-fcs.x86_64                                                                                                                                                                                                                      1/1

Installed:
 jdk1.8.0_121.x86_64 2000:1.8.0_121-fcs

Complete![root@linuxprobe ~]# java -version
java version "1.8.0_121"Java(TM) SE Runtime Environment(build 1.8.0_121-b13)
Java HotSpot(TM)64-Bit Server VM(build 25.121-b13, mixed mode)
# Set jdk environment variables
[ root@linuxprobe ~]# vi /etc/profile
# add follows to the end
export JAVA_HOME=/usr/java/defaultexport PATH=$PATH:$JAVA_HOME/bin
export CLASSPATH=.:$JAVA_HOME/jre/lib:$JAVA_HOME/lib:$JAVA_HOME/lib/tools.jar
[ root@linuxprobe ~]# source /etc/profile

Reference link: http://blog.csdn.net/gsls200808/article/details/52336745 (use curl and wget to download the latest version of JDK)

If another version of JDK is installed, please change the default value as follows:

# In java-1.8.0-openjdk as an example
[ root@linuxprobe ~]# yum install java-1.8.0-openjdk -y
[ root@linuxprobe ~]# alternatives --config java

There are 2 programs which provide 'java'.

 Selection    Command
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 /usr/java/jdk1.8.0_121/jre/bin/java
*+2   java-1.8.0-openjdk.x86_64(/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.121-0.b13.el7_3.x86_64/jre/bin/java)
# Choose the latest version of Oracle JDK installed through yum
Enter to keep the current selection[+], or type selection number:1

Create a test program to ensure that the java environment is normal

[ root@linuxprobe ~]# vi day.java
 import java.util.Calendar;classday{publicstaticvoidmain(String[] args){
  Calendar cal = Calendar.getInstance();
  int year = cal.get(Calendar.YEAR);
  int month = cal.get(Calendar.MONTH)+1;
  int day = cal.get(Calendar.DATE);
  int hour = cal.get(Calendar.HOUR_OF_DAY);
  int minute = cal.get(Calendar.MINUTE);
  System.out.println(year +"/"+ month +"/"+ day +" "+ hour +":"+ minute);}}

# compile
[ root@linuxprobe ~]# javac day.java 
[ root@linuxprobe ~]# java day
2017 /4/1221:49