方法一、安装JDK
1、查看可用的JDK版本
yum -y list java*
结果如下：
Repodata is over 2 weeks old. Install yum-cron? Or run: yum makecache fast Available Packages java-1.6.0-openjdk.x86_64 1:1.6.0.41-1.13.13.1.el7_3 os java-1.6.0-openjdk-demo.x86_64 1:1.6.0.41-1.13.13.1.el7_3 os java-1.6.0-openjdk-devel.x86_64 1:1.6.0.41-1.13.13.1.el7_3 os java-1.6.0-openjdk-javadoc.x86_64 1:1.6.0.41-1.13.13.1.el7_3 os java-1.6.0-openjdk-src.x86_64 1:1.6.0.41-1.13.13.1.el7_3 os java-1.7.0-openjdk.x86_64 1:1.7.0.261-2.6.22.2.el7_8 os java-1.7.0-openjdk-accessibility.x86_64 1:1.7.0.261-2.6.22.2.el7_8 os java-1.7.0-openjdk-demo.x86_64 1:1.7.0.261-2.6.22.2.el7_8 os java-1.7.0-openjdk-devel.x86_64 1:1.7.0.261-2.6.22.2.el7_8 os 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 1:1.8.0.292.b10-1.el7_9 updates java-1.8.0-openjdk.x86_64 1:1.8.0.292.b10-1.el7_9 updates java-1.8.0-openjdk-accessibility.i686 1:1.8.0.292.b10-1.el7_9 updates java-1.8.0-openjdk-accessibility.x86_64 1:1.8.0.292.b10-1.el7_9 updates java-1.8.0-openjdk-demo.i686 1:1.8.0.292.b10-1.el7_9 updates java-1.8.0-openjdk-demo.x86_64 1:1.8.0.292.b10-1.el7_9 updates java-1.8.0-openjdk-devel.i686 1:1.8.0.292.b10-1.el7_9 updates java-1.8.0-openjdk-devel.x86_64 1:1.8.0.292.b10-1.el7_9 updates java-1.8.0-openjdk-headless.i686 1:1.8.0.292.b10-1.el7_9 updates java-1.8.0-openjdk-headless.x86_64 1:1.8.0.292.b10-1.el7_9 updates java-1.8.0-openjdk-javadoc.noarch 1:1.8.0.292.b10-1.el7_9 updates java-1.8.0-openjdk-javadoc-zip.noarch 1:1.8.0.292.b10-1.el7_9 updates java-1.8.0-openjdk-src.i686 1:1.8.0.292.b10-1.el7_9 updates java-1.8.0-openjdk-src.x86_64 1:1.8.0.292.b10-1.el7_9 updates java-11-openjdk.i686 1:11.0.11.0.9-1.el7_9 updates java-11-openjdk.x86_64 1:11.0.11.0.9-1.el7_9 updates java-11-openjdk-demo.i686 1:11.0.11.0.9-1.el7_9 updates java-11-openjdk-demo.x86_64 1:11.0.11.0.9-1.el7_9 updates java-11-openjdk-devel.i686 1:11.0.11.0.9-1.el7_9 updates java-11-openjdk-devel.x86_64 1:11.0.11.0.9-1.el7_9 updates java-11-openjdk-headless.i686 1:11.0.11.0.9-1.el7_9 updates java-11-openjdk-headless.x86_64 1:11.0.11.0.9-1.el7_9 updates java-11-openjdk-javadoc.i686 1:11.0.11.0.9-1.el7_9 updates java-11-openjdk-javadoc.x86_64 1:11.0.11.0.9-1.el7_9 updates java-11-openjdk-javadoc-zip.i686 1:11.0.11.0.9-1.el7_9 updates java-11-openjdk-javadoc-zip.x86_64 1:11.0.11.0.9-1.el7_9 updates java-11-openjdk-jmods.i686 1:11.0.11.0.9-1.el7_9 updates java-11-openjdk-jmods.x86_64 1:11.0.11.0.9-1.el7_9 updates java-11-openjdk-src.i686 1:11.0.11.0.9-1.el7_9 updates java-11-openjdk-src.x86_64 1:11.0.11.0.9-1.el7_9 updates java-11-openjdk-static-libs.i686 1:11.0.11.0.9-1.el7_9 updates java-11-openjdk-static-libs.x86_64 1:11.0.11.0.9-1.el7_9 updates java-atk-wrapper.i686 0.30.4-5.el7 os java-atk-wrapper.x86_64 0.30.4-5.el7 os java-dirq.noarch 1.8-1.el7 epel java-dirq-javadoc.noarch 1.8-1.el7 epel java-latest-openjdk.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-debug.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-demo.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-demo-debug.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-demo-fastdebug.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-devel.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-devel-debug.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-devel-fastdebug.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-fastdebug.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-headless.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-headless-debug.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-headless-fastdebug.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-javadoc.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-javadoc-zip.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-jmods.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-jmods-debug.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-jmods-fastdebug.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-src.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-src-debug.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-src-fastdebug.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-static-libs.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-static-libs-debug.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-latest-openjdk-static-libs-fastdebug.x86_64 1:16.0.1.0.9-1.rolling.el7 epel java-oauth.noarch 20100601-13.el7 epel java-oauth-javadoc.noarch 20100601-13.el7 epel java-runtime-decompiler.noarch 3.0-2.el7 epel java-runtime-decompiler-javadoc.noarch 3.0-2.el7 epel java_cup.noarch 1:0.11a-16.el7 os java_cup-javadoc.noarch 1:0.11a-16.el7 os java_cup-manual.noarch 1:0.11a-16.el7 os javacc.noarch 5.0-10.el7 os javacc-demo.noarch 5.0-10.el7 os javacc-javadoc.noarch 5.0-10.el7 os javacc-manual.noarch 5.0-10.el7 os javacc-maven-plugin.noarch 2.6-17.el7 os javacc-maven-plugin-javadoc.noarch 2.6-17.el7 os javamail.noarch 1.4.6-8.el7 os javamail-javadoc.noarch 1.4.6-8.el7 os javapackages-tools.noarch 3.4.1-11.el7 os javaparser.noarch 1.0.11-3.el7 epel javaparser-javadoc.noarch 1.0.11-3.el7 epel javassist.noarch 3.16.1-10.el7 os javassist-javadoc.noarch 3.16.1-10.el7 os javastroke.x86_64 0.5.1-33.el7 epel javawriter.noarch 2.5.1-4.el7 epel javawriter-javadoc.noarch 2.5.1-4.el7 epel
2、查看Linux的系统位数
getconf LONG_BIT
结果为64位
3、安装1.8的jdk
yum install -y java-1.8.0-openjdk-devel.x86_64 --setopt=usr_w_check=false
安装成功后，默认安装路径在/usr/lib/jvm/下边，
注意：带-devel的安装的是jdk，而不带-devel的，实际上安装的是jre！
/usr/lib/jvm目录中内容如下：
total 4 lrwxrwxrwx 1 root root 26 Nov 20 20:38 java -> /etc/alternatives/java_sdk lrwxrwxrwx 1 root root 32 Nov 20 20:38 java-1.8.0 -> /etc/alternatives/java_sdk_1.8.0 lrwxrwxrwx 1 root root 40 Nov 20 20:38 java-1.8.0-openjdk -> /etc/alternatives/java_sdk_1.8.0_openjdk drwxr-xr-x 7 root root 4096 Nov 20 20:38 java-1.8.0-openjdk-1.8.0.312.b07-1.el7_9.x86_64 lrwxrwxrwx 1 root root 34 Nov 20 20:38 java-openjdk -> /etc/alternatives/java_sdk_openjdk lrwxrwxrwx 1 root root 21 Nov 20 20:38 jre -> /etc/alternatives/jre lrwxrwxrwx 1 root root 27 Nov 20 20:38 jre-1.8.0 -> /etc/alternatives/jre_1.8.0 lrwxrwxrwx 1 root root 35 Nov 20 20:38 jre-1.8.0-openjdk -> /etc/alternatives/jre_1.8.0_openjdk lrwxrwxrwx 1 root root 51 Nov 20 20:38 jre-1.8.0-openjdk-1.8.0.312.b07-1.el7_9.x86_64 -> java-1.8.0-openjdk-1.8.0.312.b07-1.el7_9.x86_64/jre lrwxrwxrwx 1 root root 29 Nov 20 20:38 jre-openjdk -> /etc/alternatives/jre_openjdk
4、查看jdk版本
java -version
结果
openjdk version "1.8.0_312" OpenJDK Runtime Environment (build 1.8.0_312-b07) OpenJDK 64-Bit Server VM (build 25.312-b07, mixed mode)
说明安装成功!
5、查看java的安装路径
which java
结果为：/usr/bin/java
ls -lrt /usr/bin/java
6、设置环境变量
vim /etc/profile
在profile文件末尾新增如下内容：
#set java environment JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.312.b07-1.el7_9.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
7、使配置立即生效
source /etc/profile
8、输入javac
[root@xxx ~]# 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
方法二：安装jdk
1、下载
官网下载地址：https://www.oracle.com/java/technologies/downloads/
下载完后如下所示：
2、上传到服务器
3、解压
tar -zxvf jdk-8u331-linux-x64.tar.gz
4、设置环境变量
vim /etc/profile
在profile文件末尾新增如下内容：
#set java environment JAVA_HOME=/root/jenkins/data/jdk1.8.0_331 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
使配置生效
source /etc/profile
5、查看是否生效
java -version
结果如下所示：
[root@xxx jdk1.8.0_331]# java -version java version "1.8.0_331" Java(TM) SE Runtime Environment (build 1.8.0_331-b09) Java HotSpot(TM) 64-Bit Server VM (build 25.331-b09, mixed mode)
二、卸载JDK
1、使用rpm -qa | grep java | xargs rpm -e --nodeps 批量卸载所有带有Java的文件
rpm -qa | grep java | xargs rpm -e --nodeps
2、查看linux上面所有的jdk安装包
rpm -qa | grep jdk
结果如下
copy-jdk-configs-3.3-10.el7_5.noarch java-1.8.0-openjdk-headless-1.8.0.312.b07-1.el7_9.x86_64 java-1.8.0-openjdk-1.8.0.312.b07-1.el7_9.x86_64 java-1.8.0-openjdk-devel-1.8.0.312.b07-1.el7_9.x86_64
3、rpm -e --nodeps卸载对应的包
rpm -e --nodeps copy-jdk-configs-3.3-10.el7_5.noarch rpm -e --nodeps java-1.8.0-openjdk-headless-1.8.0.312.b07-1.el7_9.x86_64 rpm -e --nodeps java-1.8.0-openjdk-1.8.0.312.b07-1.el7_9.x86_64 rpm -e --nodeps java-1.8.0-openjdk-devel-1.8.0.312.b07-1.el7_9.x86_64
如果删除不了，使用下面的命令
rpm -ev python-javapackages-3.4.1-11.el7.noarch --nodeps rpm -ev javapackages-tools-3.4.1-11.el7.noarch --nodeps rpm -ev tzdata-java-2021e-1.el7.noarch --nodeps
4、删除残留jdk文件
find / -name jdk
5、卸载jdk
rm -rf JDK地址
6、vim命令编辑文件profile
vim /etc/profile
删除下面的配置
export JAVA_HOME=/root/jenkins/data/jdk1.8.0_202 export CLASSPATH=$:CLASSPATH:$JAVA_HOME/lib/ export PATH=$PATH:$JAVA_HOME/bin
删除配置的环境变量，至此JDK卸载完毕
执行下面的命令使配置生效
source /etc/profile
7、检查下自带的jdk
rpm -qa |grep java rpm -qa |grep jdk rpm -qa |grep gcj
结果
python-javapackages-3.4.1-11.el7.noarch tzdata-java-2021e-1.el7.noarch javapackages-tools-3.4.1-11.el7.noarch
