一、安装openjdk11

  • Ⅰ、搜索安装包
    1. yum search java-11-openjdk
  1. [root@thingsboard docker]# yum search java-11-openjdk
  2. Loaded plugins: fastestmirror
  3. Loading mirror speeds from cached hostfile
  4. ==================================== N/S matched: java-11-openjdk ====================================
  5. java-11-openjdk.i686 : OpenJDK Runtime Environment 11
  6. java-11-openjdk.x86_64 : OpenJDK 11 Runtime Environment
  7. java-11-openjdk-demo.i686 : OpenJDK Demos 11
  8. java-11-openjdk-demo.x86_64 : OpenJDK 11 Demos
  9. java-11-openjdk-devel.i686 : OpenJDK Development Environment 11
  10. java-11-openjdk-devel.x86_64 : OpenJDK 11 Development Environment
  11. java-11-openjdk-headless.i686 : OpenJDK Headless Runtime Environment 11
  12. java-11-openjdk-headless.x86_64 : OpenJDK 11 Headless Runtime Environment
  13. java-11-openjdk-javadoc.i686 : OpenJDK 11 API documentation
  14. java-11-openjdk-javadoc.x86_64 : OpenJDK 11 API documentation
  15. java-11-openjdk-javadoc-zip.i686 : OpenJDK 11 API documentation compressed in a single archive
  16. java-11-openjdk-javadoc-zip.x86_64 : OpenJDK 11 API documentation compressed in a single archive
  17. java-11-openjdk-jmods.i686 : JMods for OpenJDK 11
  18. java-11-openjdk-jmods.x86_64 : JMods for OpenJDK 11
  19. java-11-openjdk-src.i686 : OpenJDK Source Bundle 11
  20. java-11-openjdk-src.x86_64 : OpenJDK 11 Source Bundle
  21. java-11-openjdk-static-libs.i686 : OpenJDK libraries for static linking 11
  22. java-11-openjdk-static-libs.x86_64 : OpenJDK 11 libraries for static linking

  • Ⅱ、安装openjdk11

    1. yum install -y java-11-openjdk

  • Ⅲ、查看当前版本

    1. java --version

二、找到JAVA安装目录

  1. [root@thingsboard ~]# which java
  2. /usr/bin/java
  1. [root@thingsboard ~]# ls -lr /usr/bin/java
  2. lrwxrwxrwx 1 root root 22 Aug 15 13:32 /usr/bin/java -> /etc/alternatives/java
  1. [root@thingsboard ~]# ls -lrt /etc/alternatives/java
  2. lrwxrwxrwx 1 root root 64 Aug 15 13:32 /etc/alternatives/java -> /usr/lib/jvm/java-11-openjdk-11.0.12.0.7-0.el7_9.x86_64/bin/java

上面的/usr/lib/jvm/java-11-openjdk-11.0.12.0.7-0.el7_9.x86_64/就是JAVA的安装路径

三、配置JAVA的环境变量

  • Ⅰ、编辑环境变量的配置文件

    1. vim /etc/profile

  • Ⅱ、在文件底部加入以下配置

    1. export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-11.0.12.0.7-0.el7_9.x86_64
    2. export JRE_HOME=$JAVA_HOME/jre
    3. export CLASSPATH=$JAVA_HOME/lib:$JRE_HOME/lib:$CLASSPATH
    4. export PATH=$JAVA_HOME/bin:$JRE_HOME/bin:$PATH

  • Ⅲ、刷新配置，使其生效

    1. source /etc/profile

  • Ⅳ、测试配置结果

    1. [root@thingsboard ~]# echo $JAVA_HOME
    2. /usr/lib/jvm/java-11-openjdk-11.0.12.0.7-0.el7_9.x86_64
    3. [root@thingsboard ~]# 
    4. [root@thingsboard ~]# 
    5. [root@thingsboard ~]# echo $JRE_HOME
    6. /usr/lib/jvm/java-11-openjdk-11.0.12.0.7-0.el7_9.x86_64/jre
    7. [root@thingsboard ~]# 
    8. [root@thingsboard ~]# 
    9. [root@thingsboard ~]# echo $PATH
    10. /usr/lib/jvm/java-11-openjdk-11.0.12.0.7-0.el7_9.x86_64/bin:/usr/lib/jvm/java-11-openjdk-11.0.12.0.7-0.el7_9.x86_64/jre/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin
    11. [root@thingsboard ~]# 
    12. [root@thingsboard ~]# 
    13. [root@thingsboard ~]# echo $CLASSPATH
    14. /usr/lib/jvm/java-11-openjdk-11.0.12.0.7-0.el7_9.x86_64/lib:/usr/lib/jvm/java-11-openjdk-11.0.12.0.7-0.el7_9.x86_64/jre/lib:
    15. [root@thingsboard ~]#

四、安装opnjdk11后，没有jre,运行不了javac的解决方案

  1. yum install java-devel