Does docker come with jdk?

Docker does not come with jdk; the docker container does not have jdk by default. If you need to run a java program, you need to install jdk in the host machine or install jdk in the container. The full name of jdk is "Java Development Kit". It is a software development toolkit in Java language, mainly used for the development of Java applications on mobile devices and embedded devices.

The operating environment of this tutorial: linux7.3 system, docker version 19.03, Dell G3 computer.

Docker comes with jdk

The docker container does not have JDK by default. If you need to run a Java program, you must either install JDK in the host machine or install JDK in the container,

The full name of jdk is "Java Development Kit", which refers to the Java language software development toolkit, which is mainly used for the development of java applications on mobile devices and embedded devices. JDK is the core of Java development, including the Java runtime environment, a bunch of Java tools and Java-based class libraries.

The following is how to install JDK in a container

1. Download the gz file of the required jdk version in the host system

2. Copy gz file to the root user directory in the container

docker cp <path to jdk gz file>/jdk-8u121-linux-x64.tar.gz <容器名称或者ID>:/root

3. Enter the container

docker exec -it <容器名称或者ID> bash

4. Unlock the gz file in the container

cd ~
tar -zxvf jdk-8u121-linux-x64.tar.gz
chown root:root ~/jdk1.8.0_121 -R

5. Establish a container system JAVA_HOME directory

mkdir /usr/lib/jvm

6. Move the jdk directory to the JAVA_HOME directory

mv ~/jdk1.8.0_121 /usr/lib/jvm

7. Install vim

yum update
yum -y install vim*

8. Set environment variables

vim ~/.bashrc
 
export JAVA_HOME=/usr/lib/jvm/jdk1.8.0_121 ## 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

9. Make the environment variables take effect immediately

source ~/.bashrc

10. Verify the JDK version

java -version

Expand knowledge

jdk (full name is Java Development Kit) is SunMicrosystems's version of Java A developer's product, it is a software development kit for the Java language, mainly used for Java applications on mobile devices and embedded devices.

JDK is the core of the entire JAVA, including Java Runtime Envirnment, a bunch of Java tools (javac/java/jdb, etc.) and Java basic class libraries (i.e. Java API including rt.jar ).

The most mainstream JDK is the JDK released by Sun. In addition to Sun, there are many companies and organizations that have developed their own JDK. IBM has developed its own JDK, and domestic Taobao has also developed its own JDK. Each organization develops its own JDK in order to improve certain aspects to meet its own needs.

JDK is a development environment for building applications, applets, and components published on the Java platform. It does not provide specific development software. What it provides is the class library and Java language specification that must be used no matter what kind of development software you use to write Java programs.

Recommended learning: "docker video tutorial"

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