yum

yum -y list java* # 查询jdk版本

...
java-1.7.0-openjdk-headless.x86_64 1:1.7.0.261-2.6.22.2.el7_8 os
java-1.7.0-openjdk-javadoc.noarch 1:1.7.0.261-2.6.22.2.el7_8 os
java-1.7.0-openjdk-src.x86_64 1:1.7.0.261-2.6.22.2.el7_8 os
java-1.8.0-openjdk.i686 1:1.8.0.352.b08-2.el7_9 updates
java-1.8.0-openjdk.x86_64 1:1.8.0.352.b08-2.el7_9 updates
java-1.8.0-openjdk-accessibility.i686 1:1.8.0.352.b08-2.el7_9 updates
java-1.8.0-openjdk-accessibility.x86_64
...

yum install -y java-1.8.0-openjdk.x86_64 # 注意 -y表示安装过程中全部选择yes

java -version
java
javac # 三个命令都没问题说明安装成功

wget

java -version # 检查是否已经安装jdk

rpm -qa | grep java # 检查是否有jdk安装包 有的话需要执行 rpm -e --nodeps 包名 删除

cd /downloads/jdk # 目录是需要自己创建的

wget https://download.oracle.com/otn/java/jdk/8u351-b10/10e8cce67c7843478f41411b7003171c/jdk-8u351-linux-x64.tar.gz # 下载jdk

tar -vxf jdk-8u351-linux-x64.tar.gz # 解压

mv jdk1.8.0_351 jdk-1.8 # 改名

mkdir /usr/lib/jvm

mv jdk-1.8 /usr/lib/jvm/jdk-1.8

vi /etc/profile # 头或者尾添加下面代码

export JAVA_HOME=/usr/lib/jvm/jdk-1.8
export PATH=$JAVA_HOME/bin:$PATH
export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar

source /etc/profile # 重新加载

java -version
java
javac # 三个命令都没问题说明安装成功