jdk环境

安装方式一  jdk环境

干净的环境 将tar包解压到 /usr/local下 版本为jdk-8u211-linux-x64.tar.gz  路径为/usr/local/jdk1.8.0_211

 /usr/local 在当前用户下执行此环境变量(将本机配置好jdk环境)

#!/bin/bash
wget http://192.168.130.150/jdk/jdk-8u211-linux-x64.tar.gz
tar xf jdk-8u211-linux-x64.tar.gz -C /usr/local/
echo "export JAVA_HOME=/usr/local/jdk1.8.0_211" >> /etc/profile.d/jdk8.sh
echo "export CLASS_PATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/jar/tools.jar:$JAVA_HOME/jre/lib" >> /etc/profile.d/jdk8.sh
echo "export PATH=$JAVA_HOME/bin:$JAVA_HOME/jre/bin:$PATH" >> /etc/profile.d/jdk8.sh
echo "export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/apr/lib" >> /etc/profile.d/jdk8.sh

chmod +x /etc/profile.d/jdk8.sh
source /etc/profile.d/jdk8.sh 
java -version

如果用脚本  需要在外面命令行执行 source /etc/profile.d/jdk8.sh   因为脚本里面加载了环境变量，外面还没有执行，重启亦可以

安装方式二 openjdk

查看CentOS自带JDK是否已安装

1	[root@test ~]# yum list installed |grep java

若有自带安装的JDK，应如下操作进行卸载CentOS系统自带Java环境

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[root@test ~]# java -version java version "1.7.0_181" OpenJDK Runtime Environment (rhel-2.6.14.8.el6_9-x86_64 u181-b00) OpenJDK 64-Bit Server VM (build 24.181-b00, mixed mode)   [root@test ~]# yum -y remove java-1.7.0-openjdk* [root@test ~]# yum -y remove tzdata-java.noarch   [root@test ~]# java --version -bash: /usr/bin/java: No such file or directory

查看yum库中的Java安装包

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[root@test ~]# yum -y list java* Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * base: centos.ustc.edu.cn * extras: centos.ustc.edu.cn * updates: centos.ustc.edu.cn base | 3.7 kB 00:00 extras | 3.4 kB 00:00 updates | 3.4 kB 00:00 Available Packages java-1.5.0-gcj.x86_64 1.5.0.0-29.1.el6 base java-1.5.0-gcj-devel.x86_64 1.5.0.0-29.1.el6 base java-1.5.0-gcj-javadoc.x86_64 1.5.0.0-29.1.el6 base java-1.5.0-gcj-src.x86_64 1.5.0.0-29.1.el6 base java-1.6.0-openjdk.x86_64 1:1.6.0.40-1.13.12.6.el6_8 updates java-1.6.0-openjdk-demo.x86_64 1:1.6.0.40-1.13.12.6.el6_8 updates java-1.6.0-openjdk-devel.x86_64 1:1.6.0.40-1.13.12.6.el6_8 updates java-1.6.0-openjdk-javadoc.x86_64 1:1.6.0.40-1.13.12.6.el6_8 updates java-1.6.0-openjdk-src.x86_64 1:1.6.0.40-1.13.12.6.el6_8 updates java-1.7.0-openjdk.x86_64 1:1.7.0.111-2.6.7.2.el6_8 updates java-1.7.0-openjdk-demo.x86_64 1:1.7.0.111-2.6.7.2.el6_8 updates java-1.7.0-openjdk-devel.x86_64 1:1.7.0.111-2.6.7.2.el6_8 updates java-1.7.0-openjdk-javadoc.noarch 1:1.7.0.111-2.6.7.2.el6_8 updates java-1.7.0-openjdk-src.x86_64 1:1.7.0.111-2.6.7.2.el6_8 updates java-1.8.0-openjdk.x86_64 1:1.8.0.101-3.b13.el6_8 updates java-1.8.0-openjdk-debug.x86_64 1:1.8.0.101-3.b13.el6_8 updates java-1.8.0-openjdk-demo.x86_64 1:1.8.0.101-3.b13.el6_8 updates java-1.8.0-openjdk-demo-debug.x86_64 1:1.8.0.101-3.b13.el6_8 updates java-1.8.0-openjdk-devel.x86_64 1:1.8.0.101-3.b13.el6_8 updates java-1.8.0-openjdk-devel-debug.x86_64 1:1.8.0.101-3.b13.el6_8 updates java-1.8.0-openjdk-headless.x86_64 1:1.8.0.101-3.b13.el6_8 updates java-1.8.0-openjdk-headless-debug.x86_64 1:1.8.0.101-3.b13.el6_8 updates java-1.8.0-openjdk-javadoc.noarch 1:1.8.0.101-3.b13.el6_8 updates java-1.8.0-openjdk-javadoc-debug.noarch 1:1.8.0.101-3.b13.el6_8 updates java-1.8.0-openjdk-src.x86_64 1:1.8.0.101-3.b13.el6_8 updates java-1.8.0-openjdk-src-debug.x86_64 1:1.8.0.101-3.b13.el6_8 updates java_cup.x86_64 1:0.10k-5.el6 base java_cup-javadoc.x86_64 1:0.10k-5.el6 base java_cup-manual.x86_64 1:0.10k-5.el6 base javacc.x86_64 4.1-0.5.el6 base javacc-demo.x86_64 4.1-0.5.el6 base javacc-manual.x86_64 4.1-0.5.el6 base javassist.noarch 3.9.0-6.el6 base javassist-javadoc.noarch 3.9.0-6.el6 base

以yum库中java-1.8.0为例, "*"表示将java-1.8.0的所有相关Java程序都安装上

1	[root@test ~]# yum -y install java-1.8.0-openjdk*

查看刚安装的Java版本信息。
输入："java -version" 可查看Java版本
输入："javac" 可查看Java的编译器命令用法

备注：一个环境，要用安装包就都用，要用yum也就都用yum，方便以后排错，openjdk有可能在有些环境下报错