在CentOS 7中安装与配置JDK8

1. 检查已经安装的jdk

rpm -qa | grep java

可能的结果如下:

java-1.7.0-openjdk-1.7.0.99-2.6.5.0.el7_2.x86_64
python-javapackages-3.4.1-11.el7.noarch
java-1.8.0-openjdk-headless-1.8.0.77-0.b03.el7_2.x86_64
java-1.8.0-openjdk-1.8.0.77-0.b03.el7_2.x86_64
tzdata-java-2016c-1.el7.noarch
javapackages-tools-3.4.1-11.el7.noarch
java-1.7.0-openjdk-headless-1.7.0.99-2.6.5.0.el7_2.x86_64

2. 移除已经安装的open-jdk及依赖的程序

yum remove tzdata-java-2016c-1.el7.noarch

此时所有的open-jdk和其它对open-jdk有依赖的软件都会被移除

3.到oracle下载jdk8, 如我下载的是jdk-8u65-linux-x64.rpm

在对应目录下执行安装命令:

rpm -ivh jdk-8u65-linux-x64.rpm

程序默认安装到 /usr/java/jdk1.8.0_65

检查安装情况:

[root@pole jdk]# java -version
java version "1.8.0_65"
Java(TM) SE Runtime Environment (build 1.8.0_65-b17)
Java HotSpot(TM) 64-Bit Server VM (build 25.65-b01, mixed mode)
[root@pole jdk]# javac -version
javac 1.8.0_65

检查文件路径:

[root@pole jdk]# whereis java
java: /usr/bin/java /usr/lib/java /etc/java /usr/share/java /usr/share/man/man1/java.1
[root@pole jdk]# ll /usr/bin/java
lrwxrwxrwx 1 root root 22 Mar 28 11:52 /usr/bin/java -> /etc/alternatives/java
[root@pole jdk]# ll /etc/alternatives/java
lrwxrwxrwx 1 root root 34 Mar 28 11:52 /etc/alternatives/java -> /usr/java/jdk1.8.0_65/jre/bin/java

添加环境变量文件:

[root@pole jdk]# vi /etc/profile.d/jdk8.sh

添加以下内容

JAVA_HOME=/usr/java/jdk1.8.0_65
JRE_HOME=/usr/java/jdk1.8.0_65/jre
CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib

export JAVA_HOME JRE_HOME CLASSPATH

使修改生效

source /etc/profile

检查是否生效

[root@pole jdk]# env|grep java
JRE_HOME=/usr/java/jdk1.8.0_65/jre
JAVA_HOME=/usr/java/jdk1.8.0_65
CLASSPATH=.:/usr/java/jdk1.8.0_65/lib/dt.jar:/usr/java/jdk1.8.0_65/lib/tools.jar:/usr/java/jdk1.8.0_65/jre/lib

到此OK了.