1、通过xshell登录centos，在Centos7上，通过yum install java，可以得到所有openjdk的版本。如图所示：
选择需要安装的版本，执行：yum install java-1.8.0-openjdk-devel-debug.x86_64 中间直接输入 y 即可。
[[email protected] ~]# yum install java-1.8.0-openjdk-devel-debug.x86_64
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Resolving Dependencies
--> Running transaction check
---> Package java-1.8.0-openjdk-devel-debug.x86_64 1:1.8.0.232.b09-0.el7_7 will be installed
--> Processing Dependency: java-1.8.0-openjdk-debug(x86-64) = 1:1.8.0.232.b09-0.el7_7 for package: 1:java-1.8.0-openjdk-devel-debug-1.8.0.232.b09-0.el7_7.x86_64
--> Processing Dependency: chkconfig >= 1.7 for package: 1:java-1.8.0-openjdk-devel-debug-1.8.0.232.b09-0.el7_7.x86_64
--> Processing Dependency: chkconfig >= 1.7 for package: 1:java-1.8.0-openjdk-devel-debug-1.8.0.232.b09-0.el7_7.x86_64
--> Processing Dependency: libjvm.so()(64bit) for package: 1:java-1.8.0-openjdk-devel-debug-1.8.0.232.b09-0.el7_7.x86_64
--> Processing Dependency: libjava.so()(64bit) for package: 1:java-1.8.0-openjdk-devel-debug-1.8.0.232.b09-0.el7_7.x86_64
--> Running transaction check
---> Package chkconfig.x86_64 0:1.3.61-5.el7 will be updated
--> Processing Dependency: chkconfig = 1.3.61-5.el7 for package: ntsysv-1.3.61-5.el7.x86_64
---> Package chkconfig.x86_64 0:1.7.4-1.el7 will be an update
---> Package java-1.8.0-openjdk-debug.x86_64 1:1.8.0.232.b09-0.el7_7 will be installed
--> Processing Dependency: java-1.8.0-openjdk-headless-debug(x86-64) = 1:1.8.0.232.b09-0.el7_7 for package: 1:java-1.8.0-openjdk-debug-1.8.0.232.b09-0.el7_7.x86_64
--> Processing Dependency: xorg-x11-fonts-Type1 for package: 1:java-1.8.0-openjdk-debug-1.8.0.232.b09-0.el7_7.x86_64
--> Processing Dependency: libXcomposite(x86-64) for package: 1:java-1.8.0-openjdk-debug-1.8.0.232.b09-0.el7_7.x86_64
--> Processing Dependency: gtk2(x86-64) for package: 1:java-1.8.0-openjdk-debug-1.8.0.232.b09-0.el7_7.x86_64
--> Processing Dependency: fontconfig(x86-64) for package: 1:java-1.8.0-openjdk-debug-1.8.0.232.b09-0.el7_7.x86_64
--> Processing Dependency: libgif.so.4()(64bit) for package: 1:java-1.8.0-openjdk-debug-1.8.0.232.b09-0.el7_7.x86_64
--> Processing Dependency: libXtst.so.6()(64bit) for package: 1:java-1.8.0-openjdk-debug-1.8.0.232.b09-0.el7_7.x86_64
--> Processing Dependency: libXrender.so.1()(64bit) for package: 1:java-1.8.0-openjdk-debug-1.8.0.232.b09-0.el7_7.x86_64
--> Processing Dependency: libXi.so.6()(64bit) for package: 1:java-1.8.0-openjdk-debug-1.8.0.232.b09-0.el7_7.x86_64
--> Processing Dependency: libXext.so.6()(64bit) for package: 1:java-1.8.0-openjdk-debug-1.8.0.232.b09-0.el7_7.x86_64
---> Package java-1.8.0-openjdk-headless.x86_64 1:1.8.0.232.b09-0.el7_7 will be installed
--> Processing Dependency: tzdata-java >= 2015d for package: 1:java-1.8.0-openjdk-headless-1.8.0.232.b09-0.el7_7.x86_64
。。。。。。。
libwayland-client.x86_64 0:1.15.0-1.el7 libwayland-server.x86_64 0:1.15.0-1.el7
libxshmfence.x86_64 0:1.2-1.el7 libxslt.x86_64 0:1.1.28-5.el7
lksctp-tools.x86_64 0:1.0.17-2.el7 mesa-libEGL.x86_64 0:18.3.4-5.el7
mesa-libGL.x86_64 0:18.3.4-5.el7 mesa-libgbm.x86_64 0:18.3.4-5.el7
mesa-libglapi.x86_64 0:18.3.4-5.el7 pango.x86_64 0:1.42.4-4.el7_7
pcsc-lite-libs.x86_64 0:1.8.8-8.el7 pixman.x86_64 0:0.34.0-1.el7
python-javapackages.noarch 0:3.4.1-11.el7 python-lxml.x86_64 0:3.2.1-4.el7
ttmkfdir.x86_64 0:3.0.9-42.el7 tzdata-java.noarch 0:2019c-1.el7
xorg-x11-font-utils.x86_64 1:7.5-21.el7 xorg-x11-fonts-Type1.noarch 0:7.5-9.el7
Dependency Updated:
chkconfig.x86_64 0:1.7.4-1.el7 freetype.x86_64 0:2.8-14.el7 glib2.x86_64 0:2.56.1-5.el7 libdrm.x86_64 0:2.4.97-2.el7 ntsysv.x86_64 0:1.7.4-1.el7
Complete!
[[email protected] ~]#
3、配置JAVA_HOME变量。
执行：echo $JAVA_HOME时：
[[email protected] ~]# echo $JAVA_HOME
[[email protected] ~]#
表示未配置JAVA_HOME,需要到/etc/profile中配置JAVA_HOME，配置JAVA_HOME如下：
[[email protected] etc]# which java
/usr/bin/java
[[email protected] etc]# ls -lrt /usr/bin/java
lrwxrwxrwx. 1 root root 22 Dec 19 16:54 /usr/bin/java -> /etc/alternatives/java
[[email protected] etc]# ls -lrt /etc/alternatives/java
lrwxrwxrwx. 1 root root 73 Dec 19 16:54 /etc/alternatives/java -> /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.232.b09-0.el7_7.x86_64/jre/bin/java
查找完之后即可配置JAVA_HOME
执行：vim /etc/profile 打开该文件进行编辑。在该文件后续追加：
export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.232.b09-0.el7_7.x86_64/bin/
export JRE_HOME=$JAVA_HOME/jre
export CLASSPATH=$JAVA_HOME/lib:$JRE_HOME/lib:$CLASSPATH
export PATH=$JAVA_HOME/bin:$JRE_HOME/bin:$PATH
然后保存退出，重新加载文件，执行 source /etc/profile 完成加载
执行：echo $JAVA_HOME 查看是否安装成功。
[[email protected] etc]# echo $JAVA_HOME
/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.232.b09-0.el7_7.x86_64/bin/
[[email protected] etc]#