安装jdk

解压

[root@iZ2ze8dv3a3meoltm5u25oZ ~]# tar zxf jdk-8u151-linux-x64.tar.gz 
[root@iZ2ze8dv3a3meoltm5u25oZ ~]# mv jdk1.8.0_151 /usr/local/jdk1.8
[root@iZ2ze8dv3a3meoltm5u25oZ ~]# rm jdk-8u151-linux-x64.tar.gz

添加变量

cat >> /etc/profile<<EOF
JAVA_HOME=/usr/local/jdk1.8/
JAVA_BIN=/usr/local/jdk1.8/bin
JRE_HOME=/usr/local/jdk1.8/jre
PATH=$PATH:/usr/local/jdk1.8/bin:/usr/local/jdk1.8/jre/bin
CLASSPATH=/usr/local/jdk1.8/jre/lib:/usr/local/jdk1.8/lib:/usr/local/jdk1.8/jre/lib/charsets.jar
EOF

使变量生效

[root@iZ2ze8dv3a3meoltm5u25pZ ~]# source /etc/profile

验证

[root@iZ2ze8dv3a3meoltm5u25pZ ~]# java -version
java version "1.8.0_151"
Java(TM) SE Runtime Environment (build 1.8.0_151-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.151-b12, mixed mode)