linux安装java的jdk环境

1.wget下载。

# wget --no-check-certificate --no-cookies --header "Cookie: oraclelicense=accept-securebackup-cookie" https://download.oracle.com/otn-pub/java/jdk/8u191-b12/2787e4a523244c269598db4e85c51e0c/jdk-8u191-linux-x64.tar.gz

2.移动到/usr/java解压。

# tar -zxvf jdk-8u191-linux-x64.tar.gz

3.修改vim /etc/profile。

 export JAVA_HOME=/usr/java/jdk1.8.0_191
 export CLASSPATH=.:$JAVA_HOME/jre/lib/rt.jar:$JAVA_HOME/lib/tools.jar
 export PATH=$PATH:$JAVA_HOME/bin

4.查看安装是否成功。

# source /etc/profile
# java -version

5.如果存在1.7jdk，需要切换链接。

 //配置链接
 # update-alternatives --install /usr/bin/java java /usr/java/jdk1.8.0_191/bin/java 300
 # update-alternatives --install /usr/bin/javac javac /usr/java/jdk1.8.0_191/bin/javac 300

 //切换链接到1.8
 # update-alternatives --config java  
 There is 1 program that provides 'java'.
  Selection    Command
 -----------------------------------------------
 *+ 1           /usr/java/jdk1.8.0_191/bin/java

 //查看java版本
 # java -version