linux下jdk安装

之前以为有记录过jdk的安装（然而并没有）。现在重新记录一下：

参考博客：https://www.cnblogs.com/Dylansuns/p/6974272.html

一、查看是否有安装JDK

java -version

显示：

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)

二、检测jdk安装包

rpm -qa | grep java

显示：

python-javapackages-3.4.1-6.el7_0.noarch
tzdata-java-2015a-1.el7.noarch
javapackages-tools-3.4.1-6.el7_0.noarch

三、卸载jdk

我使用的卸载方式：

yum remove *openjdk*

其它卸载方式（未亲测）

rpm -e --nodeps tzdata-java-2016g-2.el7.noarch
rpm -e --nodeps java-1.7.0-openjdk-1.7.0.111-2.6.7.8.el7.x86_64
rpm -e --nodeps java-1.7.0-openjdk-headless-1.7.0.111-2.6.7.8.el7.x86_64
rpm -e --nodeps java-1.8.0-openjdk-1.8.0.102-4.b14.el7.x86_64
rpm -e --nodeps java-1.8.0-openjdk-headless-1.8.0.102-4.b14.el7.x86_64

查看卸载情况：

rpm -qa | grep java

四、安装新的JDK

在官网下载JDK：http://www.oracle.com/technetwork/java/javase/downloads/index.html

解压压缩包

tar -zxvf jdk-8u161-linux-x64.tar.gz

修改profile文件（目录：/etc/profile），添加如下部分

# /etc/profile

# System wide environment and startup programs, for login setup
# Functions and aliases go in /etc/bashrc

# It's NOT a good idea to change this file unless you know what you
# are doing. It's much better to create a custom.sh shell script in
# /etc/profile.d/ to make custom changes to your environment, as this
# will prevent the need for merging in future updates.

#-----------------以下是添加部分---------------------------------
JAVA_HOME=/usr/java/jdk1.8.0_161
CLASSPATH=$JAVA_HOME/lib/
PATH=$PATH:$JAVA_HOME/bin
export PATH JAVA_HOME CLASSPATH
#-----------------以上是添加部分---------------------------------

pathmunge () {
    case ":${PATH}:" in
        *:"$1":*)
            ;;
        *)
            if [ "$2" = "after" ] ; then
                PATH=$PATH:$1
            else
                PATH=$1:$PATH
            fi
    esac
}
#下面部分省略

执行profile文件

source /etc/profile

查看新安装的JDK

java -version

安装结束