Use Linux The software package management tool of the distribution to install Java software package It's easy . However , Sometimes you need to install it manually Java. This pair is based on Java Application server （ Such as Tomcat or JBoss） Your administrator is particularly important . Many open source and proprietary software products rely on these services .

How to be in Linux Manual installation on Java
Use Linux The software package management tool of the distribution to install Java software package It's easy . However , Sometimes you need to install it manually Java. This pair is based on Java Application server （ Such as Tomcat or JBoss） Your administrator is particularly important . Many open source and proprietary software products rely on these services .

Manual installation can give users better control Java Runtime environment .

Use Linux The software package management tool of the distribution to install Java software package It's easy . However , Sometimes you need to install it manually Java. This pair is based on Java Application server （ Such as Tomcat or JBoss） Your administrator is particularly important . Many open source and proprietary software products rely on these services .

Developer or runtime Suite ？

Java virtual machine Java Virtual Machine（JVM） Provide... In two different forms ：Java Development kit Java Development Kit（JDK） or Java Runtime environment Java Runtime Environment（JRE）.

Software developers often need JDK. It includes compilation 、 Binary files required to run and test the source code . Deploy a pre-established Java Applications usually only need JRE. It does not include compilers and other development tools . Due to the improvement of security and the limitation of space , Usually installed in a production environment JRE.

obtain Java

You can download open source from the Internet Java Software . You can Red Hat Developer、Adoptium.net download OpenJDK Package files , Or from Azul download Zulu Community Edition .

install Java

Set up a directory to store Java file . I like to create a simple one called java The catalog of , So I can download and unzip the package file in a special directory ：

$ mkdir -p java/jdk

Let's use... In this example JDK. Save the downloaded file to jdk Under the table of contents . Then change to this directory ：

$ cd java/jdk
$ ls
OpenJDK11U-jdk_x64_linux_hotspot_11.0.12_7.tar.gz

Extract the packaged file . Be careful ,tar A new directory will be created ：

$ tar xvzf OpenJDK11U-jdk_x64_linux_hotspot_11.0.12_7.tar.gz
$ ls
jdk-11.0.12+7 OpenJDK11U-jdk_x64_linux_hotspot_11.0.12_7.tar.gz

Use -version Option confirmation NEW JVM Version of .

$ cd jdk-11.0.12+7/bin
$ ./java -version

JVM The version output of looks like this ：

openjdk version "11.0.12" 2021-07-20
OpenJDK Runtime Environment Temurin-11.0.12+7 (build 11.0.12+7)
OpenJDK 64-Bit Server VM Temurin-11.0.12+7 (build 11.0.12+7, mixed mode)

environment variable

To ensure that a particular application works , It needs to know exactly how to locate JVM. There are two main variables that need to be set ：JAVA_HOME and PATH.

$ echo $JAVA_HOME
$ echo $PATH

These can be found in the user's .bashrc Set in file . Make sure these variables appear in Any settings PATH Existing code for after ：

#Set the JAVA_HOME
export JAVA_HOME=~/java/jdk/jdk-11.0.12+7
#Add the JAVA_HOME to the PATH
export PATH="$JAVA_HOME/bin:$PATH"

Manual installation

There are several situations that require manual installation Java. Please consider the following three situations ：

One situation may require the use of different , Maybe earlier , In your Linux The software library of the distribution is no longer available Java edition .

Another example might be a security driven decision , namely Java It will not be installed on the operating system by default or on “ Root level ” On .

The third case is that several different versions of Java, Usually because J2EE Web Multiple instances of the application run on the same server . With the increasing use of virtual machines and containers to isolate processes , This kind of operating system sharing is not very common today . However , Due to the need to maintain different container images , The understanding of manual installation is still crucial .

summary

I demonstrated that I manually installed Java How the runtime environment , But you can make a convention that best suits your needs . Final , Manual installation gives users better control Java Runtime environment .