卸载
查看已经安装的jdk

[root@bogon jre]# rpm -qa|grep jdk
java-1.8.0-openjdk-headless-1.8.0.65-3.b17.el7.x86_64
java-1.7.0-openjdk-1.7.0.91-2.6.2.3.el7.x86_64
java-1.7.0-openjdk-headless-1.7.0.91-2.6.2.3.el7.x86_64
java-1.8.0-openjdk-1.8.0.65-3.b17.el7.x86_64

卸载命令

[root@bogon jre]# yum -y remove java-1.8.0-openjdk-headless-1.8.0.65-3.b17.el7.x86_64

卸载完成之后Java命令不被识别

[root@bogon lib]# java -version
bash: java: command not found...

安装
去官网下载jdk
解压到安装目录

# JDK1.8
wget https://beautify-breast.oss-cn-shenzhen.aliyuncs.com/BeautifyBreast/file/images/jdk-8u191-linux-x64.tar.gz

# JDK11
wget https://beautify-breast.oss-cn-shenzhen.aliyuncs.com/BeautifyBreast/file/images/jdk-11.0.16.1_linux-x64_bin.tar.gz
mkdir /usr/local/java
tar -zxvf jdk-11.0.16.1_linux-x64_bin.tar.gz -C /usr/local/java/

安装完毕之后在/etc/profile文件末尾添加

[root@bogon software]# vim /etc/profile
export JAVA_HOME=/usr/local/java/jdk-11.0.16.1
export JRE_HOME=${JAVA_HOME}/jre
export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib
export PATH=${JAVA_HOME}/bin:$PATH

使/etc/profile生效

[root@bogon jdk-11.0.16.1]# source /etc/profile

检测安装是否成功

[root@bogon jdkjdk-11.0.16.1]# java -version
java version "11.0.16.1" 2022-08-18 LTS
Java(TM) SE Runtime Environment 18.9 (build 11.0.16.1+1-LTS-1)
Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.16.1+1-LTS-1, mixed mode)
[root@bogon jdkjdk-11.0.16.1]# 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
  -nowarn                    Generate no warnings
  -verbose                   Output messages about what the compiler is doing
  -deprecation               Output source locations where deprecated APIs are used
  -classpath <path>          Specify where to find user class files and annotation processors
  -cp <path>                 Specify where to find user class files and annotation processors
  -sourcepath <path>         Specify where to find input source files
  -bootclasspath <path>      Override location of bootstrap class files
  -extdirs <dirs>            Override location of installed extensions
  -endorseddirs <dirs>       Override location of endorsed standards path
  -proc:{none,only}          Control whether annotation processing and/or compilation is done.
  -processor <class1>[,<class2>,<class3>...] Names of the annotation processors to run; bypasses default discovery process
  -processorpath <path>      Specify where to find annotation processors
  -parameters                Generate metadata for reflection on method parameters
  -d <directory>             Specify where to place generated class files
  -s <directory>             Specify where to place generated source files
  -h <directory>             Specify where to place generated native header files
  -implicit:{none,class}     Specify whether or not to generate class files for implicitly referenced files
  -encoding <encoding>       Specify character encoding used by source files
  -source <release>          Provide source compatibility with specified release
  -target <release>          Generate class files for specific VM version
  -profile <profile>         Check that API used is available in the specified profile
  -version                   Version information
  -help                      Print a synopsis of standard options
  -Akey[=value]              Options to pass to annotation processors
  -X                         Print a synopsis of nonstandard options
  -J<flag>                   Pass <flag> directly to the runtime system
  -Werror                    Terminate compilation if warnings occur
  @<filename>                Read options and filenames from file