方法一：手动解压JDK的压缩包，然后设置环境变量
1.在/usr/目录下创建java目录
[root@localhost ~]# mkdir/usr/java [root@localhost ~]# cd /usr/java
2.下载jdk,然后解压
[root@localhost java]# curl -O http://download.Oracle.com/otn-pub/java/jdk/7u79-b15/jdk-7u79-linux-x64.tar.gz [root@localhost java]# tar -zxvf jdk-7u79-linux-x64.tar.gz
3.设置环境变量
[root@localhost java]# vi /etc/profile
在profile中添加如下内容:
#set java environment JAVA_HOME=/usr/java/jdk1.7.0_79 JRE_HOME=/usr/java/jdk1.7.0_79/jre CLASS_PATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin export JAVA_HOME JRE_HOME CLASS_PATH PATH
让修改生效:
[root@localhost java]# source /etc/profile
4.验证JDK有效性
[root@localhost java]# java -version java version "1.7.0_79"Java(TM) SE Runtime Environment (build 1.7.0_79-b15) Java HotSpot(TM) 64-Bit Server VM (build 24.79-b02, mixed mode)
方法二：用yum安装JDK
1.查看yum库中都有哪些jdk版本(暂时只发现了openjdk)
[root@localhost ~]# yum search java|grep jdk ldapjdk-javadoc.x86_64 : Javadoc for ldapjdk 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.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 java-1.8.0-openjdk-demo.x86_64 : OpenJDK Demos java-1.8.0-openjdk-devel.x86_64 : OpenJDK Development Environment java-1.8.0-openjdk-headless.x86_64 : OpenJDK Runtime Environment java-1.8.0-openjdk-javadoc.noarch : OpenJDK API Documentation java-1.8.0-openjdk-src.x86_64 : OpenJDK Source Bundle ldapjdk.x86_64 : The Mozilla LDAP Java SDK
2.选择版本,进行安装
//选择1.7版本进行安装
[root@localhost ~]# yum install java-1.7.0-openjdk
//安装完之后，默认的安装目录是在: /usr/lib/jvm/java-1.7.0-openjdk-1.7.0.75.x86_64
3.设置环境变量
[root@localhost ~]# vi /etc/profile
在profile文件中添加如下内容
#set java environment JAVA_HOME=/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.75.x86_64 JRE_HOME=$JAVA_HOME/jre CLASS_PATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin export JAVA_HOME JRE_HOME CLASS_PATH PATH
让修改生效
[root@localhost java]# source /etc/profile
4.验证(同上一方法)
方法三：用rpm安装JDK
1.下载rpm安装文件
[root@localhost ~]$ curl -O http://download.oracle.com/otn-pub/java/jdk/7u79-b15/jdk-7u79-linux-x64.rpm
2.使用rpm命令安装
[root@localhost ~]# rpm -ivh jdk-7u79-linux-x64.rpm
3.设置环境变量
[root@localhost java]# vi /etc/profile
在打开的profile文件中添加如下内容
#set java environment JAVA_HOME=/usr/java/jdk1.7.0_79 JRE_HOME=/usr/java/jdk1.7.0_79/jre CLASS_PATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin export JAVA_HOME JRE_HOME CLASS_PATH PATH
让修改生效
[root@localhost java]# source /etc/profile
4.验证(同上一方法)
注:和yum安装类似，不用设置环境变量就可以运行java命令。rpm安装方式默认会把jdk安装到/usr/java/jdk1.7.0_79，然后通过三层链接，链接到/usr/bin,具体链接如下：
[root@localhost ~]# cd /bin [root@localhost bin]# ll|grep java lrwxrwxrwx. 1 root root 25 Mar 28 11:24 jar ->/usr/java/default/bin/jar lrwxrwxrwx. 1 root root 26 Mar 28 11:24 java -> /usr/java/default/bin/java lrwxrwxrwx. 1 root root 27 Mar 28 11:24 javac ->/usr/java/default/bin/javac lrwxrwxrwx. 1 root root 29 Mar 28 11:24 javadoc ->/usr/java/default/bin/javadoc lrwxrwxrwx. 1 root root 28 Mar 28 11:24 javaws ->/usr/java/default/bin/javaws lrwxrwxrwx. 1 root root 30 Mar 28 11:24 jcontrol ->/usr/java/default/bin/jcontrol [root@localhost bin]# cd /usr/java/[root@localhost java]# ll total 4lrwxrwxrwx. 1 root root 16 Mar 28 11:24 default-> /usr/java/latest drwxr-xr-x. 8 root root 4096 Mar 28 11:24 jdk1.7.0_79 lrwxrwxrwx. 1 root root 21 Mar 28 11:24 latest -> /usr/java/jdk1.7.0_79