Centos安装jdk1.8

#查找java相关
$ rpm -qa | grep java
#删除查找出的，noarch文件不需要删除，删除其他类型的文件
$ rpm -e --nodeps xxx
 

#在/usr/local下创建java路径
$ cd /usr/local
$ mkdir java
#解压tar包
$ tar -zxvf jdk-8u251-linux-x64.tar.gz 

#编辑配置文件
$ vim /etc/profile

#java environment
export JAVA_HOME=/usr/local/java/jdk1.8.0_251
export CLASSPATH=.:$JAVA_HOME/jre/lib/rt.jar:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export PATH=$PATH:$JAVA_HOME/bin

$ source /etc/profile

$ java -version

[root@dsxie jdk1.8.0_251]# java -version
java version "1.8.0_251"
Java(TM) SE Runtime Environment (build 1.8.0_251-b08)
Java HotSpot(TM) 64-Bit Server VM (build 25.251-b08, mixed mode)

#jdk1.8
export JAVA_HOME=/usr/local/java/jdk1.8.0_251
export CLASSPATH=.:$JAVA_HOME/jre/lib/rt.jar:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export PATH=$PATH:$JAVA_HOME/bin

#jdk11
export JAVA_HOME=/usr/local/java/jdk-11.0.7
export CLASSPATH=.:$JAVA_HOME/jre/lib/rt.jar:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export PATH=$PATH:$JAVA_HOME/bin

#修改后重新source /etc/profile

$ rm /usr/bin/java
$ rm /usr/bin/javac

$ ln -s /usr/local/java/jdk-11.0.7/bin/javac /usr/bin/javac
$ ln -s /usr/local/java/jdk-11.0.7/bin/java /usr/bin/java