CentOS安装多个JDK版本、自动切换环境变量 |
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老项目使用JDK1.7，因此系统中安装多个JDK版本，为了便于切换，修改了/etc/profile文件，每次加载文件自动获取对应JDK版本的环境变量。 检查Java 版本 // 检查系统java 版本 [root@centos7-18 data]# java -version openjdk version "1.8.0_272" OpenJDK Runtime Environment (build 1.8.0_272-b10) OpenJDK 64-Bit Server VM (build 25.272-b10, mixed mode) [root@centos7-18 data]# 检查yum java 安装版本 [root@centos7-18 data]# yum list | grep java-1.7 java-1.7.0-openjdk.x86_64 1:1.7.0.261-2.6.22.2.el7_8 @base java-1.7.0-openjdk-devel.x86_64 1:1.7.0.261-2.6.22.2.el7_8 @base java-1.7.0-openjdk-headless.x86_64 1:1.7.0.261-2.6.22.2.el7_8 @base java-1.7.0-openjdk-accessibility.x86_64 1:1.7.0.261-2.6.22.2.el7_8 base java-1.7.0-openjdk-demo.x86_64 1:1.7.0.261-2.6.22.2.el7_8 base java-1.7.0-openjdk-javadoc.noarch 1:1.7.0.261-2.6.22.2.el7_8 base java-1.7.0-openjdk-src.x86_64 1:1.7.0.261-2.6.22.2.el7_8 base [root@centos7-18 data]# 安装JDK 1.7 yum -y install java-1.7.0-openjdk-devel.x86_64 设置JDK环境变量 vim /etc/profile根据当前版本java命令路径，获取对应的JAVA_HOME路径 #export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.252.b09-2.el7_8.x86_64 #JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk # 注意路径和文件名 // 在/etc/profile定义，每次根据当前java 切换不同的Java环境变量 JAVA_PATH=$(readlink -f /usr/bin/java) # 获取当前java命令路径 JAVA_HOME=${JAVA_PATH%/jre/bin*} # 截取JAVA_HOME路径，shell语法参考{var%.*} CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JAVA_HOME/jre/lib/rt.jar PATH=$JAVA_HOME/bin:$PATH export JAVA_HOME CLASSPATH PATHshell语法链接: shell之文件路径截取. // 环境变量生效 source /etc/profile // 验证环境变量 echo $JAVA_HOME && echo $CLASSPATH && echo $PATH 切换JDK当前JDK1.8 // 当前JDK版本及环境变量 [root@centos7-18 ~]# java -version openjdk version "1.8.0_272" OpenJDK Runtime Environment (build 1.8.0_272-b10) OpenJDK 64-Bit Server VM (build 25.272-b10, mixed mode) [root@centos7-18 ~]# [root@centos7-18 ~]# echo $JAVA_HOME && echo $CLASSPATH && echo $PATH /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.272.b10-1.el7_9.x86_64 .:/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.272.b10-1.el7_9.x86_64/lib/dt.jar:/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.272.b10-1.el7_9.x86_64/lib/tools.jar:/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.272.b10-1.el7_9.x86_64/jre/lib/rt.jar /usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/usr/lib/jvm/java-1.8.0-openjdk/bin:/root/bin:/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.272.b10-1.el7_9.x86_64/bin:/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.261-2.6.22.2.el7_8.x86_64/bin:/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.272.b10-1.el7_9.x86_64/bin [root@centos7-18 ~]#切换JDK1.7，并重新加载环境变量 // 切换JDK1.8 [root@centos7-18 ~]# alternatives --config java 共有 2 个提供“java”的程序。 选项 命令 ----------------------------------------------- *+ 1 java-1.8.0-openjdk.x86_64 (/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.272.b10-1.el7_9.x86_64/jre/bin/java) 2 java-1.7.0-openjdk.x86_64 (/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.261-2.6.22.2.el7_8.x86_64/jre/bin/java) 按 Enter 保留当前选项[+]，或者键入选项编号：2 [root@centos7-18 ~]# // 重新加载环境变量 [root@centos7-18 ~]# source /etc/profile [root@centos7-18 ~]# 检查切换结果 // 检查JDK 版本 [root@centos7-18 ~]# java -version java version "1.7.0_261" OpenJDK Runtime Environment (rhel-2.6.22.2.el7_8-x86_64 u261-b02) OpenJDK 64-Bit Server VM (build 24.261-b02, mixed mode) [root@centos7-18 ~]# // 检查环境变量 [root@centos7-18 ~]# echo $JAVA_HOME && echo $CLASSPATH && echo $PATH /usr/lib/jvm/java-1.7.0-openjdk-1.7.0.261-2.6.22.2.el7_8.x86_64 .:/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.261-2.6.22.2.el7_8.x86_64/lib/dt.jar:/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.261-2.6.22.2.el7_8.x86_64/lib/tools.jar:/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.261-2.6.22.2.el7_8.x86_64/jre/lib/rt.jar /usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/usr/lib/jvm/java-1.8.0-openjdk/bin:/root/bin:/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.272.b10-1.el7_9.x86_64/bin:/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.261-2.6.22.2.el7_8.x86_64/bin:/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.272.b10-1.el7_9.x86_64/bin:/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.261-2.6.22.2.el7_8.x86_64/bin [root@centos7-18 ~]# |
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