1、先查看centos中自带的jdk并卸载
[root@root ~]# rpm -qa | grep java //查看
tzdata-java-2016c-1.el6.noarch
java-1.6.0-openjdk-1.6.0.38-1.13.10.4.el6.x86_64
java-1.7.0-openjdk-1.7.0.99-2.6.5.1.el6.x86_64
[root@root ~]# rpm -e --allmatches --nodeps java-1.6.0-openjdk-1.6.0.38-1.13.10.4.el6.x86_64 //卸载
[root@root ~]# rpm -e --allmatches --nodeps java-1.7.0-openjdk-1.7.0.99-2.6.5.1.el6.x86_64 //卸载
[root@root ~]# rpm -qa | grep java //再次查看
tzdata-java-2016c-1.el6.noarch
2、yum 命令查找jdk 两种方法：
//第一种：
[root@root ~]# yum -y list java*
已加载插件：fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
* base: mirrors.neusoft.edu.cn
* extras: mirrors.neusoft.edu.cn
* updates: mirrors.huaweicloud.com
可安装的软件包
java-1.5.0-gcj.x86_64 1.5.0.0-29.1.el6 base
java-1.5.0-gcj-devel.x86_64 1.5.0.0-29.1.el6 base
java-1.5.0-gcj-javadoc.x86_64 1.5.0.0-29.1.el6 base
java-1.5.0-gcj-src.x86_64 1.5.0.0-29.1.el6 base
java-1.6.0-openjdk.x86_64 1:1.6.0.41-1.13.13.1.el6_8 base //jdk6
java-1.6.0-openjdk-demo.x86_64 1:1.6.0.41-1.13.13.1.el6_8 base
java-1.6.0-openjdk-devel.x86_64 1:1.6.0.41-1.13.13.1.el6_8 base
java-1.6.0-openjdk-javadoc.x86_64 1:1.6.0.41-1.13.13.1.el6_8 base
java-1.6.0-openjdk-src.x86_64 1:1.6.0.41-1.13.13.1.el6_8 base
java-1.7.0-openjdk.x86_64 1:1.7.0.201-2.6.16.0.el6_10 updates //jdk7
java-1.7.0-openjdk-demo.x86_64 1:1.7.0.201-2.6.16.0.el6_10 updates
java-1.7.0-openjdk-devel.x86_64 1:1.7.0.201-2.6.16.0.el6_10 updates
java-1.7.0-openjdk-javadoc.noarch 1:1.7.0.201-2.6.16.0.el6_10 updates
java-1.7.0-openjdk-src.x86_64 1:1.7.0.201-2.6.16.0.el6_10 updates
java-1.8.0-openjdk.x86_64 1:1.8.0.191.b12-0.el6_10 updates //jdk8
java-1.8.0-openjdk-debug.x86_64 1:1.8.0.191.b12-0.el6_10 updates
java-1.8.0-openjdk-demo.x86_64 1:1.8.0.191.b12-0.el6_10 updates
java-1.8.0-openjdk-demo-debug.x86_64 1:1.8.0.191.b12-0.el6_10 updates
java-1.8.0-openjdk-devel.x86_64 1:1.8.0.191.b12-0.el6_10 updates
java-1.8.0-openjdk-devel-debug.x86_64 1:1.8.0.191.b12-0.el6_10 updates
java-1.8.0-openjdk-headless.x86_64 1:1.8.0.191.b12-0.el6_10 updates
java-1.8.0-openjdk-headless-debug.x86_64 1:1.8.0.191.b12-0.el6_10 updates
java-1.8.0-openjdk-javadoc.noarch 1:1.8.0.191.b12-0.el6_10 updates
java-1.8.0-openjdk-javadoc-debug.noarch 1:1.8.0.191.b12-0.el6_10 updates
java-1.8.0-openjdk-src.x86_64 1:1.8.0.191.b12-0.el6_10 updates
java-1.8.0-openjdk-src-debug.x86_64 1:1.8.0.191.b12-0.el6_10 updates
java_cup.x86_64 1:0.10k-5.el6 base
java_cup-javadoc.x86_64 1:0.10k-5.el6 base
java_cup-manual.x86_64 1:0.10k-5.el6 base
javacc.x86_64 4.1-0.5.el6 base
javacc-demo.x86_64 4.1-0.5.el6 base
javacc-manual.x86_64 4.1-0.5.el6 base
javassist.noarch 3.9.0-6.el6 base
javassist-javadoc.noarch 3.9.0-6.el6 base
//第二种：
[root@root ~]# yum search jdk
已加载插件：fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
* base: mirrors.neusoft.edu.cn
* extras: mirrors.neusoft.edu.cn
* updates: mirrors.huaweicloud.com
===================================== N/S Matched: jdk ======================================
copy-jdk-configs.noarch : JDKs configuration files copier
java-1.6.0-openjdk.x86_64 : OpenJDK Runtime Environment //jdk6
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 //jdk7
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 //jdk8
java-1.8.0-openjdk-debug.x86_64 : OpenJDK Runtime Environment with full debug on
java-1.8.0-openjdk-demo.x86_64 : OpenJDK Demos
java-1.8.0-openjdk-demo-debug.x86_64 : OpenJDK Demos with full debug on
java-1.8.0-openjdk-devel.x86_64 : OpenJDK Development Environment
java-1.8.0-openjdk-devel-debug.x86_64 : OpenJDK Development Environment with full debug on
java-1.8.0-openjdk-headless.x86_64 : OpenJDK Runtime Environment
java-1.8.0-openjdk-headless-debug.x86_64 : OpenJDK Runtime Environment with full debug on
java-1.8.0-openjdk-javadoc.noarch : OpenJDK API Documentation
java-1.8.0-openjdk-javadoc-debug.noarch : OpenJDK API Documentation for packages with debug
: on
java-1.8.0-openjdk-src.x86_64 : OpenJDK Source Bundle
java-1.8.0-openjdk-src-debug.x86_64 : OpenJDK Source Bundle for packages with debug on
ldapjdk-javadoc.x86_64 : Javadoc for ldapjdk
icedtea-web.x86_64 : Additional Java components for OpenJDK - Java browser plug-in and Web
: Start implementation
ldapjdk.x86_64 : The Mozilla LDAP Java SDK
Name and summary matches only, use "search all" for everything.
3、安装jdk 作者安装 java-1.8.0-openjdk.x86_64
[root@root ~]# yum install java-1.8.0-openjdk.x86_64
已加载插件：fastestmirror, refresh-packagekit, security
设置安装进程
Loading mirror speeds from cached hostfile
* base: mirrors.neusoft.edu.cn
* extras: mirrors.neusoft.edu.cn
* updates: mirrors.huaweicloud.com
解决依赖关系
--> 执行事务检查
---> Package java-1.8.0-openjdk.x86_64 1:1.8.0.191.b12-0.el6_10 will be 安装
--> 处理依赖关系 java-1.8.0-openjdk-headless = 1:1.8.0.191.b12-0.el6_10，它被软件包 1:java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64 需要
--> 处理依赖关系 libjvm.so(SUNWprivate_1.1)(64bit)，它被软件包 1:java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64 需要
--> 处理依赖关系 libjli.so(SUNWprivate_1.1)(64bit)，它被软件包 1:java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64 需要
--> 处理依赖关系 libjava.so(SUNWprivate_1.1)(64bit)，它被软件包 1:java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64 需要
--> 处理依赖关系 libjvm.so()(64bit)，它被软件包 1:java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64 需要
--> 处理依赖关系 libjli.so()(64bit)，它被软件包 1:java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64 需要
--> 处理依赖关系 libjava.so()(64bit)，它被软件包 1:java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64 需要
--> 处理依赖关系 libawt.so()(64bit)，它被软件包 1:java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64 需要
--> 执行事务检查
---> Package java-1.8.0-openjdk-headless.x86_64 1:1.8.0.191.b12-0.el6_10 will be 安装
--> 处理依赖关系 tzdata-java >= 2014f-1，它被软件包 1:java-1.8.0-openjdk-headless-1.8.0.191.b12-0.el6_10.x86_64 需要
--> 处理依赖关系 nss >= 3.36.0，它被软件包 1:java-1.8.0-openjdk-headless-1.8.0.191.b12-0.el6_10.x86_64 需要
--> 执行事务检查
---> Package nss.x86_64 0:3.21.0-8.el6 will be 升级
--> 处理依赖关系 nss = 3.21.0-8.el6，它被软件包 nss-sysinit-3.21.0-8.el6.x86_64 需要
--> 处理依赖关系 nss(x86-64) = 3.21.0-8.el6，它被软件包 nss-tools-3.21.0-8.el6.x86_64 需要
---> Package nss.x86_64 0:3.36.0-9.el6_10 will be an update
--> 处理依赖关系 nss-util >= 3.36.0，它被软件包 nss-3.36.0-9.el6_10.x86_64 需要
--> 处理依赖关系 nspr >= 4.19.0，它被软件包 nss-3.36.0-9.el6_10.x86_64 需要
--> 处理依赖关系 libnssutil3.so(NSSUTIL_3.33)(64bit)，它被软件包 nss-3.36.0-9.el6_10.x86_64 需要
--> 处理依赖关系 libnssutil3.so(NSSUTIL_3.31)(64bit)，它被软件包 nss-3.36.0-9.el6_10.x86_64 需要
--> 处理依赖关系 libnssutil3.so(NSSUTIL_3.24)(64bit)，它被软件包 nss-3.36.0-9.el6_10.x86_64 需要
---> Package tzdata-java.noarch 0:2018g-1.el6 will be 安装
--> 执行事务检查
---> Package nspr.x86_64 0:4.11.0-1.el6 will be 升级
---> Package nspr.x86_64 0:4.19.0-1.el6 will be an update
---> Package nss-sysinit.x86_64 0:3.21.0-8.el6 will be 升级
---> Package nss-sysinit.x86_64 0:3.36.0-9.el6_10 will be an update
---> Package nss-tools.x86_64 0:3.21.0-8.el6 will be 升级
---> Package nss-tools.x86_64 0:3.36.0-9.el6_10 will be an update
---> Package nss-util.x86_64 0:3.21.0-2.el6 will be 升级
---> Package nss-util.x86_64 0:3.36.0-1.el6 will be an update
--> 完成依赖关系计算
依赖关系解决
=================================================================================================
软件包 架构 版本 仓库 大小
=================================================================================================
正在安装:
java-1.8.0-openjdk x86_64 1:1.8.0.191.b12-0.el6_10 updates 212 k
为依赖而安装:
java-1.8.0-openjdk-headless x86_64 1:1.8.0.191.b12-0.el6_10 updates 32 M
tzdata-java noarch 2018g-1.el6 updates 186 k
为依赖而更新:
nspr x86_64 4.19.0-1.el6 base 114 k
nss x86_64 3.36.0-9.el6_10 updates 865 k
nss-sysinit x86_64 3.36.0-9.el6_10 updates 53 k
nss-tools x86_64 3.36.0-9.el6_10 updates 460 k
nss-util x86_64 3.36.0-1.el6 base 72 k
事务概要
=================================================================================================
Install 3 Package(s)
Upgrade 5 Package(s)
总下载量：34 M
确定吗？[y/N]：y //确定下载
下载软件包：
(1/8): java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64.rpm | 212 kB 00:00
(2/8): java-1.8.0-openjdk-headless-1.8.0.191.b12-0.el6_10.x86_64.rpm | 32 MB 00:10
(3/8): nspr-4.19.0-1.el6.x86_64.rpm | 114 kB 00:00
(4/8): nss-3.36.0-9.el6_10.x86_64.rpm | 865 kB 00:00
(5/8): nss-sysinit-3.36.0-9.el6_10.x86_64.rpm | 53 kB 00:00
(6/8): nss-tools-3.36.0-9.el6_10.x86_64.rpm | 460 kB 00:00
(7/8): nss-util-3.36.0-1.el6.x86_64.rpm | 72 kB 00:00
(8/8): tzdata-java-2018g-1.el6.noarch.rpm | 186 kB 00:00
-------------------------------------------------------------------------------------------------
总计 2.6 MB/s | 34 MB 00:13
warning: rpmts_HdrFromFdno: Header V3 RSA/SHA1 Signature, key ID c105b9de: NOKEY
Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
Importing GPG key 0xC105B9DE:
Userid : CentOS-6 Key (CentOS 6 Official Signing Key) <[email protected]>
Package: centos-release-6-8.el6.centos.12.3.x86_64 (@anaconda-CentOS-201605220104.x86_64/6.8)
From : /etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
确定吗？[y/N]：y //确定 y
运行 rpm_check_debug
执行事务测试
事务测试成功
执行事务
Warning: RPMDB altered outside of yum.
** Found 1 pre-existing rpmdb problem(s), 'yum check' output follows:
1:libreoffice-ure-4.3.7.2-2.el6.x86_64 has missing requires of libjvm.so()(64bit)
正在升级 : nspr-4.19.0-1.el6.x86_64 1/13
正在升级 : nss-util-3.36.0-1.el6.x86_64 2/13
正在升级 : nss-3.36.0-9.el6_10.x86_64 3/13
正在升级 : nss-sysinit-3.36.0-9.el6_10.x86_64 4/13
正在安装 : tzdata-java-2018g-1.el6.noarch 5/13
正在安装 : 1:java-1.8.0-openjdk-headless-1.8.0.191.b12-0.el6_10.x86_64 6/13
正在安装 : 1:java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64 7/13
正在升级 : nss-tools-3.36.0-9.el6_10.x86_64 8/13
清理 : nss-tools-3.21.0-8.el6.x86_64 9/13
清理 : nss-3.21.0-8.el6.x86_64 10/13
清理 : nss-sysinit-3.21.0-8.el6.x86_64 11/13
清理 : nss-util-3.21.0-2.el6.x86_64 12/13
清理 : nspr-4.11.0-1.el6.x86_64 13/13
Verifying : 1:java-1.8.0-openjdk-headless-1.8.0.191.b12-0.el6_10.x86_64 1/13
Verifying : nss-sysinit-3.36.0-9.el6_10.x86_64 2/13
Verifying : nss-util-3.36.0-1.el6.x86_64 3/13
Verifying : 1:java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64 4/13
Verifying : nss-tools-3.36.0-9.el6_10.x86_64 5/13
Verifying : nspr-4.19.0-1.el6.x86_64 6/13
Verifying : nss-3.36.0-9.el6_10.x86_64 7/13
Verifying : tzdata-java-2018g-1.el6.noarch 8/13
Verifying : nss-util-3.21.0-2.el6.x86_64 9/13
Verifying : nss-3.21.0-8.el6.x86_64 10/13
Verifying : nss-sysinit-3.21.0-8.el6.x86_64 11/13
Verifying : nss-tools-3.21.0-8.el6.x86_64 12/13
Verifying : nspr-4.11.0-1.el6.x86_64 13/13
已安装:
java-1.8.0-openjdk.x86_64 1:1.8.0.191.b12-0.el6_10
作为依赖被安装:
java-1.8.0-openjdk-headless.x86_64 1:1.8.0.191.b12-0.el6_10 tzdata-java.noarch 0:2018g-1.el6
作为依赖被升级:
nspr.x86_64 0:4.19.0-1.el6 nss.x86_64 0:3.36.0-9.el6_10
nss-sysinit.x86_64 0:3.36.0-9.el6_10 nss-tools.x86_64 0:3.36.0-9.el6_10
nss-util.x86_64 0:3.36.0-1.el6
完毕！
4、检验安装
[root@root ~]# java -version
openjdk version "1.8.0_191"
OpenJDK Runtime Environment (build 1.8.0_191-b12)
OpenJDK 64-Bit Server VM (build 25.191-b12, mixed mode)
5、yum 命令安装默认安装路径为 /usr/lib/jvm
//查看安装路径
[root@root ~]# cd /usr/lib/jvm
[root@root jvm]# ll
总用量 4
drwxr-xr-x 3 root root 4096 12月 22 11:08 java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64 //这里
lrwxrwxrwx 1 root root 21 12月 22 11:09 jre -> /etc/alternatives/jre
lrwxrwxrwx 1 root root 27 12月 22 11:09 jre-1.8.0 -> /etc/alternatives/jre_1.8.0
lrwxrwxrwx 1 root root 52 12月 22 11:09 jre-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64 -> java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre
lrwxrwxrwx 1 root root 52 12月 22 11:09 jre-1.8.0-openjdk.x86_64 -> java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre
lrwxrwxrwx 1 root root 29 12月 22 11:09 jre-openjdk -> /etc/alternatives/jre_openjdk
// /etc/alternatives 的目录下面会有个java链接，指向/usr/lib/jvm/jre-1.8.0-openjdk.x86_64/bin/java
[root@root jvm]# cd /etc/alternatives
[root@root alternatives]# ll
总用量 108
……
lrwxrwxrwx 1 root root 46 12月 22 11:09 java -> /usr/lib/jvm/jre-1.8.0-openjdk.x86_64/bin/java
lrwxrwxrwx 1 root root 78 12月 22 11:09 java.1.gz -> /usr/share/man/man1/java-java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64.1.gz
lrwxrwxrwx 1 root root 73 12月 22 11:09 jjs -> /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre/bin/jjs
lrwxrwxrwx 1 root root 77 12月 22 11:09 jjs.1.gz -> /usr/share/man/man1/jjs-java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64.1.gz
lrwxrwxrwx 1 root root 65 12月 22 11:09 jre -> /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre
lrwxrwxrwx 1 root root 65 12月 22 11:09 jre_1.8.0 -> /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre
lrwxrwxrwx 1 root root 65 12月 22 11:09 jre_1.8.0_exports -> /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre
lrwxrwxrwx 1 root root 68 12月 22 11:09 jre_exports -> /usr/lib/jvm-exports/jre-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64
lrwxrwxrwx 1 root root 65 12月 22 11:09 jre_openjdk -> /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre
lrwxrwxrwx 1 root root 65 12月 22 11:09 jre_openjdk_exports -> /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-0.el6_10.x86_64/jre
……
6、设置jdk环境变量
[root@root alternatives]# vim /etc/profile
在文件最后加入如下配置：
#set java environment
JAVA_HOME=/usr/lib/jvm/jre-1.8.0-openjdk.x86_64
PATH=$PATH:$JAVA_HOME/bin
CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export JAVA_HOME CLASSPATH PATH
保存退出。
7、使profile文件立马生效
[root@root alternatives]# . /etc/profile // . 后面有个空格
---------------------