linux（centos 7）安装 jdk8

卸载自带的open jdk

centos 7 自带open jdk1.8版本，但由于不支持javac，从而无法完成代码的编译操作，故卸载此jdk安装jdk8。

查看已安装的jdk

[root@localhost jdk]# rpm -qa|grep jdk
java-1.8.0-openjdk-headless-1.8.0.345.b01-1.el7_9.x86_64
java-1.7.0-openjdk-1.7.0.261-2.6.22.2.el7_8.x86_64
copy-jdk-configs-3.3-10.el7_5.noarch
java-1.8.0-openjdk-1.8.0.345.b01-1.el7_9.x86_64
java-1.7.0-openjdk-headless-1.7.0.261-2.6.22.2.el7_8.x86_64

卸载命令

[root@localhost jdk]# yum -y remove java-1.8.0-openjdk-headless-1.8.0.345.b01-1.el7_9.x86_64
[root@localhost jdk]# yum -y remove java-1.7.0-openjdk-1.7.0.261-2.6.22.2.el7_8.x86_64
...

卸载完成之后Java命令不被识别

[root@localhost jdk]# java -version
bash: java: command not found...

安装 jdk8

去官网下载jdk：http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html 解压到安装目录

解压 jdk8

tar -zxvf jdk-8u101-linux-x64.tar.gz

设置环境变量

 vim /etc/profile

添加如下：

#java
export JAVA_HOME=/home/xxx/bonc/download/jdk
export CLASSPATH=.:$JAVA_HOME/lib:$JAVA_HOME/jre/lib
export PATH=$PATH:$JAVA_HOME/bin:$JAVA_HOME/jre/bin

使文件生效

 source /etc/profile

检验是否安装成功

[root@localhost ~]# java -version
java version "1.8.0_152"
Java(TM) SE Runtime Environment (build 1.8.0_152-b16)
Java HotSpot(TM) 64-Bit Server VM (build 25.152-b16, mixed mode)

[root@localhost ~]# javac
Usage: javac  
where possible options include: