CentOS安装OracleJDK

实践证明，OracleJDK比OpenJDK快不止一星半点，换了之后立马从满负载降到个位数负载。

1、卸载openjdk

# rpm -qa | grep -E '^(java|jdk)'
# yum remove -y java-1.8.0-openjdk java-1.8.0-openjdk-headless

2、上oracle官网下载rpm包，这里要注意cookie，不能直接下载

# wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" "http://download.oracle.com/otn-pub/java/jdk/8u144-b01/090f390dda5b47b9b721c7dfaa008135/jdk-8u144-linux-x64.rpm"

3、安装jdk

# yum install -y jdk-8u144-linux-x64.rpm

4、导出环境变量

# vim /etc/profile.d/java.sh
export JAVA_HOME=/usr/java/latest
export PATH=$JAVA_HOME/bin:$PATH

# source /etc/profile.d/java.sh

5、验证

# java -version
java version "1.8.0_144"
Java(TM) SE Runtime Environment (build 1.8.0_144-b01)
Java HotSpot(TM) 64-Bit Server VM (build 25.144-b01, mixed mode)

参考：
https://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html