CentOS 6.5安装jdk1.8

1.查看是否已经安装jdk

java -version  

2.建立目录（系统中没有安装jdk状况）

mkdir /usr/local/java

3.解压到/usr/local/java目录中

tar -zxvf jdk-8u151-linux-x64.tar.gz -C /usr/local/java

4.设置jdk环境

vi /etc/profile

5.在末尾添加

JAVA_HOME=/usr/local/java/jdk1.8.0_151
JRE_HOME=/usr/local/java/jdk1.8.0_151/jre
CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib
PATH=$JAVA_HOME/bin:$PATH
export PATH JAVA_HOME CLASSPATH

6.使环境变量生效

source /etc/profile

7.看本身配置是否正确

echo $JAVA_HOME
echo $CLASSPATH
echo $PATH

8.若是系统已经安装了其余版本的Java，修改默认JDK

update-alternatives --install /usr/bin/java java /usr/java/jdk1.8.0_66/bin/java 300

update-alternatives --install /usr/bin/javac javac /usr/java/jdk1.8.0_66/bin/javac 300

update-alternatives --config java

update-alternatives --config javac

9.检验是否安装成功

java -version

成功显示：

java version "1.8.0_66"
Java(TM) SE Runtime Environment (build 1.8.0_66-b17)
Java HotSpot(TM) 64-Bit Server VM (build 25.65-b01, mixed mode)