安装JDK

1、yum方式安装JDK

1.1、配置yum仓库

gzip /etc/yum.repos.d/*
curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
curl -o /etc/yum.repos.d/epel-7.repo http://mirrors.aliyun.com/repo/epel-7.repo
yum clean all
yum makecache

1.2、安装jdk

yum install java -y

# 版本：java-1.8.0-openjdk

2、二进制方式安装

2.1、下载jdk

https://www.oracle.com/cn/java/technologies/downloads/
# 自行注册帐号下载

这里使用jdk-8u152-linux-x64.tar.gz

2.2、安装jdk

tar xf jdk-8u152-linux-x64.tar.gz -C /usr/local/
ln -s /usr/local/jdk1.8.0_152 /usr/local/jdk
cat >>/etc/profile<<'EOF'
export JAVA_HOME=/usr/local/jdk
export PATH=$JAVA_HOME/bin:$JAVA_HOME/jre/bin:$PATH
export CLASSPATH=.$CLASSPATH:$JAVA_HOME/lib:$JAVA_HOME/jre/lib:$JAVA_HOME/lib/tools.jar
EOF
source /etc/profile

2.3、验证是否安装成功

2.3.1、查询版本

]# 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)

2.3.2、检查javac

]# javac
Usage: javac <options> <source files>
where possible options include:
  -g                         Generate all debugging info
  -g:none                    Generate no debugging info
  -g:{lines,vars,source}     Generate only some debugging info
...