Linux:Ubuntu 14.04 Server 离线安装Jjava8（及在线安装）

• （离线安装）首先，通过winscp上传本地下载好的jdk-8u102-linux-x64.gz

• （离线安装）将jdk-8u102-linux-x64.gz解压到到/usr/lib/jvm下，并把文件夹名重命名为java-8-oracle:

hadoop@master:/usr/lib$ mkdir jvm
hadoop@master:/usr/lib$ ls

。。。jvm 。。。
hadoop@master:/usr/lib$ cd /home/hadoop
hadoop@master:~$ sudo cp -r jdk-8u102-linux-x64.gz /usr/lib
hadoop@master:~$ cd /usr/lib

hadoop@master:/usr/lib$ ls

... jdk-8u102-linux-x64.gz ...

hadoop@master:/usr/lib$ sudo tar -zxvf jdk-8u102-linux-x64.gz -C jvm/

hadoop@master:/usr/lib$ cd jvm
hadoop@master:/usr/lib/jvm$ ls
jdk1.8.0_102

hadoop@master:/usr/lib$ cd ..
hadoop@master:/usr/lib$ sudo rm jdk-8u102-linux-x64.gz
hadoop@master:/usr/lib$ cd jvm
hadoop@master:/usr/lib/jvm$ mv jdk1.8.0_102/ java-8-oracle
mv: cannot move ‘jdk1.8.0_102/’ to ‘java-8-oracle’: Permission denied
hadoop@master:/usr/lib/jvm$ sudo mv jdk1.8.0_102/ java-8-oracle/
hadoop@master:/usr/lib/jvm$ ls
java-8-oracle
hadoop@master:/usr/lib/jvm$

• （离线安装）设置环境变量

hadoop@master:~$ sudo vim /etc/profile
在profile文件末尾追加一下行：

export JAVA_HOME=/usr/lib/jvm/java-8-oracle
export JRE_HOME=/usr/lib/jvm/java-8-oracle
export PATH=$JAVA_HOME/bin:$JAVA_HOME/jre/bin:$PATH
export CLASSPATH=$CLASS_PATH::$JAVA_HOME/lib:$JAVA_HOME/jre/lib

（esc,:wq!保存）
hadoop@master:~$ sudo update-alternatives --install /usr/bin/Java java /usr/lib/jvm/java-8-oracle/bin/java 300
update-alternatives: using /usr/lib/jvm/java-8-oracle/bin/java to provide /usr/bin/Java (java) in auto mode
hadoop@master:~$ sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/java-8-oracle/bin/javac 300
update-alternatives: using /usr/lib/jvm/java-8-oracle/bin/javac to provide /usr/bin/javac (javac) in auto mode
hadoop@master:~$ sudo update-alternatives --config java
There is only one alternative in link group java (providing /usr/bin/Java): /usr/lib/jvm/java-8-oracle/bin/java
Nothing to configure.
hadoop@master:~$ sudo update-alternatives --config javac
There is only one alternative in link group javac (providing /usr/bin/javac): /usr/lib/jvm/java-8-oracle/bin/javac
Nothing to configure.

•  （离线安装）测试是否安装好

java -version我测试不行，于是重启了服务器，发现可以。

hadoop@master:~$ java -version
java version "1.8.0_102"
Java(TM) SE Runtime Environment (build 1.8.0_102-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.102-b14, mixed mode)

• 在线安装方法一：

sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
sudo apt-get install Oracle-java8-Installer

如果在执行 sudo add-apt-repository ppa:webupd8team/java 命令时，提示“Cannot add PPA:xxx”，一般是因为CA证书损坏。执行如下命令修复：

sudo apt-get install --reinstall ca-certificates

设置JAVA_HOME环境变量：

$ vim /etc/profile

在文件最前面添加如下单独一行（注意 = 号前后不能有空格），并保存：

export JAVA_HOME=/usr/lib/jvm/java-8-oracle

/*按esc 输入 :wq保存并退出*/

• 在线安装方法二：

wget http://download.oracle.com/otn-pub/java/jdk/8u161-b12/2f38c3b165be4555a1fa6e98c45e0808/jdk-8u161-linux-x64.tar.gz?AuthParam=1522506006_6fffc05b7c064c1b0023fd4a4f8612b8
mv jdk-8u161-linux-x64.tar.gz\?AuthParam\=1522506006_6fffc05b7c064c1b0023fd4a4f8612b8 jdk-8u161-linux-x64.tar.gz
mkdir /usr/local/java/
tar -zxvf jdk-8u161-linux-x64.tar.gz -C /usr/local/java/

vi /etc/profile

在/etc/profile 末尾添加以下记录：
# config java class path
export JAVA_HOME=/usr/local/java/jdk1.8.0_161
export JRE_HOME=${JAVA_HOME}/jre
export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib
export PATH=${JAVA_HOME}/bin:$PATH

source /etc/profile

测试
java -version
[root@localhost jdk1.8.0_161]# java -version
java version "1.8.0_161"
Java(TM) SE Runtime Environment (build 1.8.0_161-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.161-b12, mixed mode)
[root@localhost jdk1.8.0_161]# vi /etc/profile

针对方法二，也可以参考：https://blog.csdn.net/fuyuwei2015/article/details/73195936

参考：http://blog.csdn.net/sddi1989/article/details/7995042