1.1  系统环境：

[root@nginx-daili tools]# cat/etc/redhat-release

CentOS Linux release 7.0.1406 (Core)

[root@nginx-daili tools]# uname -r

3.10.0-123.el7.x86_64

[root@nginx-daili tools]# uname -n

nginx-daili

[root@nginx-daili tools]# uname -m

x86_64

 

 

1.2  下载JDK 软件并校验包

下载编译安装包

wget http://download.oracle.com/otn-pub/java/jdk/8u73-b02/jdk-8u73-linux-x64.tar.gz

校验包

[root@nginx-daili tools]# md5sumjdk-8u73-linux-x64.tar.gz

1b0120970aa8bc182606a16bf848a686  jdk-8u73-linux-x64.tar.gz

 

[root@nginx-daili tools]# catjdk-8u73-linux-x64.md5

jdk-8u73-linux-x64.tar.gz md5: 1b0120970aa8bc182606a16bf848a686

[root@nginx-daili tools]#

 

 

1.3  解压jdk程序

[root@nginx-daili tools]# tar zxf jdk-8u73-linux-x64.tar.gz

[root@nginx-daili tools]# mv jdk1.8.0_73 /usr/lib/

1.4  创建 jdk程序目录的软链接，方便jdk以后升级

思路，给jdk 程序目录创建软链接为jdk或jvm,此处为/usr/lib/jdk软链接 （yum 安装的jdk环境默认为/usr/lib/jvm），然后给程序中的 java 和javac创建软链接到/usr/bin/下，把默认的改名。

[root@nginx-daili tools]# ln -s /usr/lib/jdk1.8.0_73/usr/lib/jdk

[root@nginx-daili tools]# mv /usr/bin/java/usr/bin/java.bak

[root@nginx-daili tools]# ln -s /usr/lib/jdk/jre/bin/java/usr/bin/java                 

[root@nginx-daili tools]# ln -s /usr/lib/jdk/bin/javac/usr/bin/javac

[root@nginx-daili tools]# ll /usr/bin/java*

lrwxrwxrwx. 1 root root 27 3月  11 09:23 /usr/bin/java ->/usr/local/jdk/jre/bin/java

lrwxrwxrwx. 1 root root 22 3月  11 08:00 /usr/bin/java.bak-> /etc/alternatives/java

lrwxrwxrwx. 1 root root 24 3月  11 09:23 /usr/bin/javac-> /usr/local/jdk/bin/java

 

创建 java 和javac软链接，方便软件升级

[root@nginx-daili tools]# ll /usr/lib/java*

lrwxrwxrwx. 1 root root 35 3月  11 09:13 /usr/local/java ->/usr/local/jdk1.8.0_73/jre/bin/java

lrwxrwxrwx. 1 root root 32 3月  11 09:13 /usr/local/javac ->/usr/local/jdk1.8.0_73/bin/javac

 

1.5  设置java环境变量

cp -p /etc/profile /etc/profile.bak$(date+%F)

 [root@nginx-daili usr]# tail -5 /etc/profile

##set environment

export JAVA_HOME=/usr/lib/jdk

export JRE_HOME=${JAVA_HOME}/jre

export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib

export PATH=${JAVA_HOME}/bin:$PATH

 

1.6  设置默认JDK（可选操作）

由于系统中可能会有默认的其他版本JDK，所以，为了将我们安装的JDK设置为默认JDK版本，还要进行如下工作。

update-alternatives --install /usr/bin/javajava /usr/lib/jvm/java7/bin/java 300

update-alternatives --install/usr/bin/javac javac /usr/lib/jvm/java7/bin/javac 300

update-alternatives --install /usr/bin/jarjar /usr/lib/jvm/java7/bin/jar 300 

update-alternatives --install/usr/bin/javah javah /usr/lib/jvm/java7/bin/javah 300 

update-alternatives --install/usr/bin/javap javap /usr/lib/jvm/java7/bin/javap 300 

执行下面命令，设置默认版本，此命令执行后，系统会列出当前存在的各种JDK版本，会提示你选择

# update-alternatives --config java

 

1.7  测试成功

[root@nginx-daili usr]# which java

/usr/lib/jdk/bin/java

[root@nginx-daili usr]# which javac

/usr/lib/jdk/bin/javac

[root@nginx-daili usr]# java -version

java version "1.8.0_73"

Java(TM) SE Runtime Environment (build1.8.0_73-b02)

Java HotSpot(TM) 64-Bit Server VM (build25.73-b02, mixed mode)