用yum安装JDK
首先检查jdk是否安装, rpm -qa | grep java 或者 java -version，或者用find找到了就rm -rf删包.就是这么干脆!
1.查看yum库中都有哪些jdk版本(暂时只发现了openjdk)
[root@localhost ~]# yum search java|grep jdk
ldapjdk-javadoc.x86_64 : Javadoc for ldapjdk
java-1.6.0-openjdk.x86_64 : OpenJDK Runtime Environment
java-1.6.0-openjdk-demo.x86_64 : OpenJDK Demos
java-1.6.0-openjdk-devel.x86_64 : OpenJDK Development Environment
java-1.6.0-openjdk-javadoc.x86_64 : OpenJDK API Documentation
java-1.6.0-openjdk-src.x86_64 : OpenJDK Source Bundle
java-1.7.0-openjdk.x86_64 : OpenJDK Runtime Environment
java-1.7.0-openjdk-demo.x86_64 : OpenJDK Demos
java-1.7.0-openjdk-devel.x86_64 : OpenJDK Development Environment
java-1.7.0-openjdk-javadoc.noarch : OpenJDK API Documentation
java-1.7.0-openjdk-src.x86_64 : OpenJDK Source Bundle
java-1.8.0-openjdk.x86_64 : OpenJDK Runtime Environment
java-1.8.0-openjdk-demo.x86_64 : OpenJDK Demos
java-1.8.0-openjdk-devel.x86_64 : OpenJDK Development Environment
java-1.8.0-openjdk-headless.x86_64 : OpenJDK Runtime Environment
java-1.8.0-openjdk-javadoc.noarch : OpenJDK API Documentation
java-1.8.0-openjdk-src.x86_64 : OpenJDK Source Bundle
ldapjdk.x86_64 : The Mozilla LDAP Java SDK
2.选择版本,进行安装
//选择1.7版本进行安装
[root@localhost ~]# yum install java-1.8.0-openjdk.x86_64
//安装完之后，默认的安装目录是在: /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.161-0.b14.el7_4.x86_64
3.设置环境变量
[root@localhost ~]# vi /etc/profile
在profile文件中添加如下内容
#set java environment
JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.161-0.b14.el7_4.x86_64
JRE_HOME=$JAVA_HOME/jre
CLASS_PATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib
PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin
export JAVA_HOME JRE_HOME CLASS_PATH PATH
让修改生效
[root@localhost java]# source /etc/profile
[root@nicknailo jvm]# java -version
openjdk version "1.8.0_161"
OpenJDK Runtime Environment (build 1.8.0_161-b14)
OpenJDK 64-Bit Server VM (build 25.161-b14, mixed mode)
安装成功1
