我们编译一个java文件里发现提示没有安装java编译器
Command 'javac' not found, but can be installed with: sudo apt install openjdk-11-jdk-headless # version 11.0.11+9-0ubuntu2~20.04, or sudo apt install default-jdk # version 2:1.11-72 sudo apt install openjdk-13-jdk-headless # version 13.0.7+5-0ubuntu1~20.04 sudo apt install openjdk-16-jdk-headless # version 16.0.1+9-1~20.04 sudo apt install openjdk-17-jdk-headless # version 17+35-1~20.04 sudo apt install openjdk-8-jdk-headless # version 8u292-b10-0ubuntu1~20.04 sudo apt install ecj # version 3.16.0-1
打开终端输入：
apt-cache search openjdk
查看下资源库中JDK的相应版本
default-jdk-headless - Standard Java or Java compatible Development Kit (headless) default-jre - 标准 Java 或兼容 Java 的运行环境 default-jre-headless - 标准 Java 或兼容 Java 的运行环境（headless） openjdk-11-jre - OpenJDK Java 运行时环境，使用 Hotspot JIT default-jdk - Standard Java or Java compatible Development Kit default-jdk-doc - Standard Java or Java compatible Development Kit (documentation) openjdk-11-dbg - Java runtime based on OpenJDK (debugging symbols) openjdk-11-doc - OpenJDK Development Kit (JDK) documentation openjdk-11-jdk - OpenJDK Development Kit (JDK) openjdk-11-jdk-headless - OpenJDK Development Kit (JDK) (headless) openjdk-11-jre-headless - OpenJDK Java runtime, using Hotspot JIT (headless) openjdk-11-source - OpenJDK Development Kit (JDK) source files libreoffice - office productivity suite (metapackage) openjdk-8-jre - OpenJDK Java 运行时环境，使用 Hotspot JIT crypto-policies - unify the crypto policies used by different applications and libraries jtreg - Regression Test Harness for the OpenJDK platform libhsdis0-fcml - HotSpot disassembler plugin using FCML libjax-maven-plugin - Using the xjc goal with OpenJDK 11+ openjdk-11-demo - Java runtime based on OpenJDK (demos and examples) openjdk-11-jre-dcevm - Alternative VM for OpenJDK 11 with enhanced class redefinition openjdk-11-jre-zero - Alternative JVM for OpenJDK, using Zero openjdk-8-dbg - Java runtime based on OpenJDK (debugging symbols) openjdk-8-demo - Java runtime based on OpenJDK (demos and examples) openjdk-8-doc - OpenJDK Development Kit (JDK) documentation openjdk-8-jdk - OpenJDK Development Kit (JDK) openjdk-8-jdk-headless - OpenJDK Development Kit (JDK) (headless)
我们安装JDK－8
sudo apt install openjdk-8-jdk
正在读取软件包列表... 完成 正在分析软件包的依赖关系树 正在读取状态信息... 完成 将会同时安装下列软件： ca-certificates-java fonts-dejavu-extra java-common libatk-wrapper-java libatk-wrapper-java-jni libice-dev libpthread-stubs0-dev libsm-dev libx11-dev libxau-dev libxcb1-dev libxdmcp-dev libxt-dev openjdk-8-jdk-headless openjdk-8-jre openjdk-8-jre-headless x11proto-core-dev x11proto-dev xorg-sgml-doctools xtrans-dev 建议安装： default-jre libice-doc libsm-doc libx11-doc libxcb-doc libxt-doc openjdk-8-demo openjdk-8-source visualvm icedtea-8-plugin fonts-ipafont-gothic fonts-ipafont-mincho fonts-wqy-microhei fonts-wqy-zenhei 下列【新】软件包将被安装： ca-certificates-java fonts-dejavu-extra java-common libatk-wrapper-java libatk-wrapper-java-jni libice-dev libpthread-stubs0-dev libsm-dev libx11-dev libxau-dev libxcb1-dev libxdmcp-dev libxt-dev openjdk-8-jdk openjdk-8-jdk-headless openjdk-8-jre openjdk-8-jre-headless x11proto-core-dev x11proto-dev xorg-sgml-doctools xtrans-dev 升级了 0 个软件包，新安装了 21 个软件包，要卸载 0 个软件包，有 0 个软件包未被升级。 需要下载 43.4 MB 的归档。 解压缩后会消耗 162 MB 的额外空间。 您希望继续执行吗？ [Y/n] y
可见jre等一些软件同时被安装
正在处理用于 ca-certificates (20210119~20.04.2) 的触发器 ... Updating certificates in /etc/ssl/certs... 0 added, 0 removed; done. Running hooks in /etc/ca-certificates/update.d... done. done. 正在处理用于 sgml-base (1.29.1) 的触发器 ... 正在设置 x11proto-dev (2019.2-1ubuntu1) ... 正在设置 libxau-dev:amd64 (1:1.0.9-0ubuntu1) ... 正在设置 libice-dev:amd64 (2:1.0.10-0ubuntu1) ... 正在设置 libsm-dev:amd64 (2:1.2.3-1) ... 正在设置 libxdmcp-dev:amd64 (1:1.1.3-0ubuntu1) ... 正在设置 x11proto-core-dev (2019.2-1ubuntu1) ... 正在设置 libxcb1-dev:amd64 (1.14-2) ... 正在设置 libx11-dev:amd64 (2:1.6.9-2ubuntu1.2) ... 正在设置 libxt-dev:amd64 (1:1.1.5-1) ...
配置环境变量, 编辑如下文件
vim ~/.bashrc
在最后一行加:
export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64 export PATH=$JAVA_HOME/bin:$PATH export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
测试jdk是否安装成功:
java -version openjdk version "1.8.0_292" OpenJDK Runtime Environment (build 1.8.0_292-8u292-b10-0ubuntu1~20.04-b10) OpenJDK 64-Bit Server VM (build 25.292-b10, mixed mode)
完成安装