linux下安装ｊｄｋ

linux下安装jdk
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• 创建一个目录用于存放解压后的文件，并解压缩到该目录下

  sudo mkdir  /opt/java8
  sudo tar -zxvf jdk-8u221-linux-x64.tar.gz -C  /opt/java8

• 修改环境变量
  sudo vim ~/.bashrc

  • 进入文件，末尾追加如下内容：
    export JAVA_HOME=/opt/java8/jdk1.8.0_221 //这里要注意目录要换成自己- 解压的jdk目录

        export JRE_HOME=${JAVA_HOME}/jre  
        export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib  
        export PATH=${JAVA_HOME}/bin:$PATH
    
    
    
    - 使环境变量生效
    ` source ~/.bashrc`
    - 设置系统默认jdk

  sudo update-alternatives –install /usr/bin/java java /opt/java8/jdk1.8.0_221/bin/java 300
  sudo update-alternatives –install /usr/bin/javac javac /opt/java8/jdk1.8.0_221/bin/javac 300
  sudo update-alternatives –install /usr/bin/jar jar /opt/java8/jdk1.8.0_221/bin/jar 300
  sudo update-alternatives –install /usr/bin/javah javah /opt/java8/jdk1.8.0_221/bin/javah 300
  sudo update-alternatives –install /usr/bin/javap javap /opt/java8/jdk1.8.0_221/bin/javap 300
  ```

  • 然后执行：
    sudo update-alternatives --config java

• 测试是否安装成功
  java -version
  突发情况