在Linux中利⽤yum安装JDK的实现步骤
⼀、卸载centos⾃带的jdk
1.查看当前的jdk版本，并卸载
root@localhost opt]# rpm -qa|grep java
java-1.6.0-openjdk-1.6.0.37-1.13.9.4.el5_11
tzdata-java-2015g-1.el5
//卸载
[root@localhost opt]# rpm -e --allmatches --nodeps java-1.6.0-openjdk-1.6.0.37-1.13.9.4.el5_11
[root@localhost opt]# rpm -e --allmatches --nodeps tzdata-java-2015g-1.el5
⼆、安装Jdk
1.查java相关得列表
[root@localhost jre-1.6.0-openjdk.x86_64]# yum -y list java*
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* addons: mirrors.btte
* base: centos.ustc.edu
* extras: centos.ustc.edu
* updates: centos.ustc.edu
Installed Packages
java-1.6.0-openjdk.x86_64          1:1.6.0.37-1.13.9.4.el5_11        installed
Available Packages
java-1.4.2-gcj-compat.x86_64          1.4.2.0-40jpp.115          base
java-1.4.2-gcj-compat-devel.i386        1.4.2.0-40jpp.115          base
java-1.4.2-gcj-compat-devel.x86_64        1.4.2.0-40jpp.115          base
java-1.4.2-gcj-compat-javadoc.x86_64        1.4.2.0-40jpp.115          base
java-1.4.2-gcj-compat-src.x86_64        1.4.2.0-40jpp.115          base
java-1.6.0-openjdk-demo.x86_64        1:1.6.0.37-1.13.9.4.el5_11        updates
java-1.6.0-openjdk-devel.x86_64        1:1.6.0.37-1.13.9.4.el5_11        updates
java-1.6.0-openjdk-javadoc.x86_64        1:1.6.0.37-1.13.9.4.el5_11        updates
java-1.6.0-openjdk-src.x86_64        1:1.6.0.37-1.13.9.4.el5_11        updates
java-1.7.0-openjdk.x86_64          1:1.7.0.91-2.6.2.1.el5_11        updates
java-1.7.0-openjdk-demo.x86_64        1:1.7.0.91-2.6.2.1.el5_11        updates
java-1.7.0-openjdk-devel.x86_64        1:1.7.0.91-2.6.2.1.el5_11        updates
java-1.7.0-openjdk-javadoc.x86_64        1:1.7.0.91-2.6.2.1.el5_11        updates
java-1.7.0-openjdk-src.x86_64        1:1.7.0.91-2.6.2.1.el5_11        updates
java_cup.x86_64            1:0.10-0.k.6jpp.1          base
java_cup-javadoc.x86_64          1:0.10-0.k.6jpp.1          base
java_cup-manual.x86_64          1:0.10-0.k.6jpp.1          base
javacc.x86_64            4.0-3jpp.3            base
javacc-demo.x86_64            4.0-3jpp.3            base
javacc-manual.x86_64            4.0-3jpp.3            base
或
[root@localhost jre-1.6.0-openjdk.x86_64]# yum search jdk
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* addons: mirrors.btte
* base: centos.ustc.edu
* extras: centos.ustc.edu
* updates: centos.ustc.edu
========================================================== Matched: jdk ========================================================== java-1.6.0-openjdk.x86_64 : OpenJDK Runtime Environment
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
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.x86_64 : OpenJDK API Documentation
java-1.7.0-openjdk-src.x86_64 : OpenJDK Source Bundle
gnu-crypto-sasl-jdk1.4.x86_64 : Gnu Crypto SASL API
jakarta-commons-beanutils.x86_64 : Jakarta Commons BeanUtils Package
jakarta-commons-collections.x86_64 : Jakarta Commons Collections Package
jakarta-commons-launcher.x86_64 : The Launcher Component is designed to be a cross platform Java application launcher.
ldapjdk.x86_64 : The Mozilla LDAP Java SDK
ldapjdk-javadoc.x86_64 : Javadoc for ldapjdk
mockobjects-alt-jdk1.4.x86_64 : Mockable API for JDK 1.4
mockobjects-jdk1.4.x86_64 : MockObjects for 1.4 JDK
2.安装jdk
[root@localhost ~]# yum install java-1.6.0-openjdk.x86_64
……
Total download size: 44 M
Is this ok [y/N]: y
3.安装完成之后，验证
[root@localhost ~]# java -versionjdk最新下载安装步骤
java version "1.6.0_37"
OpenJDK Runtime Environment (IcedTea6 1.13.9) (rhel-1.13.9.4.el5_11-x86_64)
OpenJDK 64-Bit Server VM (build 23.25-b01, mixed mode)
4.通过yum默认安装的路径为
/usr/lib/jvm
[root@localhost ~]# cd /usr/lib/jvm
[root@localhost jvm]# ll
total 24
drwxr-xr-x 3 root root 4096 Jan 12 20:01 java-1.6.0-openjdk-1.6.0.37.x86_64
lrwxrwxrwx 1 root root 21 Jan 12 20:01 jre -> /etc/alternatives/jre
lrwxrwxrwx 1 root root 27 Jan 12 20:01 jre-1.6.0 -> /etc/alternatives/jre_1.6.0
lrwxrwxrwx 1 root root 38 Jan 12 20:01 jre-1.6.0-openjdk.x86_64 -> java-1.6.0-openjdk-1.6.0.37.x86_64/jre
lrwxrwxrwx 1 root root 29 Jan 12 20:01 jre-openjdk -> /etc/alternatives/jre_openjdk
如果机器上同时安装了多个jdk的话，java命令只能指向⼀个版本的jdk，为了在全局中⽅便修改jdk版本  /etc/alternatives的⽬录下⾯会有个java链接，指向默认需要执⾏的版本的jdk的bin/java 命令
[root@localhost jvm]# cd /etc/alternatives
[root@localhost alternatives]# ll
total 204
lrwxrwxrwx 1 root root 46 Jan 12 20:01 java -> /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/java
⽽/etc/alternatives/java⼜会被软连接到/usr/bin/java
5.将jdk的安装路径加⼊到JAVA_HOME
⽅法⼀：
[root@localhost bin]# vi /etc/profile
在⽂件最后加⼊：
#set java environment
JAVA_HOME=/usr/lib/jvm/jre-1.6.0-openjdk.x86_64
PATH=$PATH:$JAVA_HOME/bin
CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export JAVA_HOME CLASSPATH PATH
修改/etc/profile之后让其⽣效
[root@localhost alternatives]# . /etc/profile
注意 . 之后应有⼀个空格
⽅法⼆：
或者是安装上⾯创建java命令的形式，以⽅便修改
[root@localhost jvm]# cd /etc/alternatives
[root@localhost alternatives]# ln -s /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/ java_home
创建⼀个/etc/alternatives/java_home的软连接，将该连接指向到当前Jdk的根⽬录
然后将改连接的路径加进去
#set java environment
JAVA_HOME=/etc/alternatives/java_home
PATH=$PATH:$JAVA_HOME/bin
CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export JAVA_HOME CLASSPATH PATH
[root@localhost alternatives]# export |grep JAVA_HOME
declare -x JAVA_HOME="/etc/alternatives/java_home"
总结
以上就是这篇⽂章的全部内容，希望⼤家能够喜欢。

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