Linux安装配置JDK

Linux(Ubuntu24.04)安装配置open-jdk

 

一、软件包自动安装配置版本

1.检查是否安装

查看Java版本号：

java -version

2.安装

$ sudo apt install openjdk-8-jdk

安装到了哪里？

javac在/usr/lib/jvm/java-8-openjdk-amd64/bin/

java在/usr/lib/jvm/java-8-openjdk-amd64/jre/bin

 

javac

mikeli@mikeli-DELL:/usr/share/doc/openjdk-8-jdk-headless$ whereis javac
javac: /usr/bin/javac /usr/share/man/man1/javac.1.gz             
mikeli@mikeli-DELL:/usr/share/doc/openjdk-8-jdk-headless$ ll /usr/bin/javac
lrwxrwxrwx 1 root root 23 Jan 26 15:38 /usr/bin/javac -> /etc/alternatives/javac*
mikeli@mikeli-DELL:/usr/share/doc/openjdk-8-jdk-headless$ ll /etc/alternatives/javac
lrwxrwxrwx 1 root root 43 Jan 26 15:38 /etc/alternatives/javac -> /usr/lib/jvm/java-8-openjdk-amd64/bin/javac*

 

java

mikeli@mikeli-DELL:~/code/java$ whereis java
java: /usr/bin/java /usr/share/java /usr/share/man/man1/java.1.gz
mikeli@mikeli-DELL:~/code/java$ ll /usr/bin/java
lrwxrwxrwx 1 root root 22 Jan 26 15:38 /usr/bin/java -> /etc/alternatives/java*
mikeli@mikeli-DELL:~/code/java$ ll /etc/alternatives/java
lrwxrwxrwx 1 root root 46 Jan 26 15:38 /etc/alternatives/java -> /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java*

 

 

/usr/lib/jvm/java-8-openjdk-amd64/bin/目录

mikeli@mikeli-DELL:/usr/share/doc/openjdk-8-jdk-headless$ ll /usr/lib/jvm/java-8-openjdk-amd64/bin/
total 524
drwxr-xr-x 2 root root  4096 Apr  5 13:31 ./
drwxr-xr-x 7 root root  4096 Apr  5 13:31 ../
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 appletviewer*
-rwxr-xr-x 1 root root 14680 Jan 26 15:38 clhsdb*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 extcheck*
-rwxr-xr-x 1 root root 14680 Jan 26 15:38 hsdb*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 idlj*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 jar*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 jarsigner*
lrwxrwxrwx 1 root root    15 Jan 26 15:38 java -> ../jre/bin/java*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 javac*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 javadoc*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 javah*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 javap*
-rwxr-xr-x 1 root root  2806 Jan 26 15:38 java-rmi.cgi*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 jcmd*
-rwxr-xr-x 1 root root 14688 Jan 26 15:38 jconsole*
-rwxr-xr-x 1 root root 14680 Jan 26 15:38 jdb*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 jdeps*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 jfr*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 jhat*
-rwxr-xr-x 1 root root 14712 Jan 26 15:38 jinfo*
lrwxrwxrwx 1 root root    14 Jan 26 15:38 jjs -> ../jre/bin/jjs*
-rwxr-xr-x 1 root root 14712 Jan 26 15:38 jmap*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 jps*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 jrunscript*
-rwxr-xr-x 1 root root 14680 Jan 26 15:38 jsadebugd*
-rwxr-xr-x 1 root root 14712 Jan 26 15:38 jstack*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 jstat*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 jstatd*
lrwxrwxrwx 1 root root    18 Jan 26 15:38 keytool -> ../jre/bin/keytool*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 native2ascii*
lrwxrwxrwx 1 root root    15 Jan 26 15:38 orbd -> ../jre/bin/orbd*
lrwxrwxrwx 1 root root    18 Jan 26 15:38 pack200 -> ../jre/bin/pack200*
lrwxrwxrwx 1 root root    21 Jan 26 15:38 policytool -> ../jre/bin/policytool*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 rmic*
lrwxrwxrwx 1 root root    15 Jan 26 15:38 rmid -> ../jre/bin/rmid*
lrwxrwxrwx 1 root root    22 Jan 26 15:38 rmiregistry -> ../jre/bin/rmiregistry*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 schemagen*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 serialver*
lrwxrwxrwx 1 root root    21 Jan 26 15:38 servertool -> ../jre/bin/servertool*
lrwxrwxrwx 1 root root    20 Jan 26 15:38 tnameserv -> ../jre/bin/tnameserv*
lrwxrwxrwx 1 root root    20 Jan 26 15:38 unpack200 -> ../jre/bin/unpack200*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 wsgen*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 wsimport*
-rwxr-xr-x 1 root root 14664 Jan 26 15:38 xjc*

 /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/目录

mikeli@mikeli-DELL:~/code/java$ ll /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/
total 280
drwxr-xr-x 2 root root   4096 Apr  5 13:31 ./
drwxr-xr-x 5 root root   4096 Mar 24 06:54 ../
-rwxr-xr-x 1 root root  14632 Jan 26 15:38 java*
-rwxr-xr-x 1 root root  14664 Jan 26 15:38 jjs*
-rwxr-xr-x 1 root root  14664 Jan 26 15:38 keytool*
-rwxr-xr-x 1 root root  14720 Jan 26 15:38 orbd*
-rwxr-xr-x 1 root root  14664 Jan 26 15:38 pack200*
-rwxr-xr-x 1 root root  14664 Jan 26 15:38 policytool*
-rwxr-xr-x 1 root root  14664 Jan 26 15:38 rmid*
-rwxr-xr-x 1 root root  14664 Jan 26 15:38 rmiregistry*
-rwxr-xr-x 1 root root  14664 Jan 26 15:38 servertool*
-rwxr-xr-x 1 root root  14720 Jan 26 15:38 tnameserv*
-rwxr-xr-x 1 root root 111736 Jan 26 15:38 unpack200*

 

看来/usr/lib/jvm/java-8-openjdk-amd64是主目录

 

mikeli@mikeli-DELL:/usr/share/doc$ 

 

 

3.配置文件在哪？

配置path和classpath

Linux path :

mikeli@mikeli-DELL:~$ echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/snap/bin

 

classpath

mikeli@mikeli-DELL:~/software$ echo $CLASSPATH
 

 

临时配置（只对本窗口生效，新开窗口不生效）

path

mikeli@mikeli-DELL:~/software/netbeans_new/nbbuild/netbeans/bin$ export PATH="/home/mikeli/software/netbeans_new/nbbuild/netbeans/bin:$PATH"
mikeli@mikeli-DELL:~/software/netbeans_new/nbbuild/netbeans/bin$ echo $PATH
/home/mikeli/software/netbeans_new/nbbuild/netbeans/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/snap/bin

 classpath

mikeli@mikeli-DELL:~$ export CLASSPATH="/home/mikeli/software/guava-28.0-jre.jar:$CLASSPATH"
mikeli@mikeli-DELL:~$ echo $CLASSPATH
/home/mikeli/software/guava-28.0-jre.jar:

 永久生效

For bash, edit the startup file (~/.bashrc):

mikeli@mikeli-DELL:~/software$ vim ~/.bashrc 

path：在.bashrc文件中加上

PATH=/home/mikeli/software/netbeans_new/nbbuild/netbeans/bin:$PATH
export PATH

classpath：在.bashrc文件中加上

CLASSPATH=/home/mikeli/software/guava-28.0-jre.jar:$CLASSPATH
export CLASSPATH

 

 使配置生效

mikeli@mikeli-DELL:~/software$ source /etc/profile

 （新开窗口）环境变量设置生效

 

#要新打开一个窗口
mikeli@mikeli-DELL:~/software$ echo $PATH
/home/mikeli/software/netbeans_new/nbbuild/netbeans/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/snap/bin

 

＃要新打开一个窗口
mikeli@mikeli-DELL:~/software$ echo $CLASSPATH
/home/mikeli/software/guava-28.0-jre.jar:

 

参考文档

PATH and CLASSPATH (The Java™ Tutorials > Essential Java Classes > The Platform Environment)

Setting the Class Path

 What is a classpath and how do I set it?

 Linux进阶之环境变量文件/etc/profile、/etc/bashrc、/etc/environment

 

 

二、下载文件自行解压配置版本

 

三、源代码本地编译版本