文章目录
在linux上安装Java环境 -JDK21
从官网上下载 JDK21-Linux版本
我们首先从官网上下载 linux JDK 的安装版本，下载地址：
JDK官方下载地址
JDK21 上传到虚拟机 Centos上
将下载好的 JDK21-Linux 版本 上传到我们的linux服务器上，例如你本地的虚拟机中安装的linux 环境
上传工具你可以使用 xshell 和 xftp； 你也可以使用 Mobaxterm；
下载Mobaxterm链接地址：
填写好虚拟机linux的ip地址，用户名，点击确定，会让你填写密码，填写完毕后即可连接对应服务器
上传JDK21-Linux
将本地文件上传到对应的linux服务器上
创建JDK21解压目录并解压
首先切换到你下载的JDK目录下
创建jdk存放目录
mkdir /usr/local/java
将压缩包解压到上述目录当中
tar -zxvf jdk-21_linux-64_bin.tar.gz -C /usr/local/java
切换到 jdk 存放目录
cd /usr/local/java
查看结果如下，证明解压成功
[root@localhost java]# ls jdk-21.0.5/
bin conf include jmods legal lib LICENSE man README release
配置JAVA环境变量
创建软连接
一般linux可能会有自己自带的java环境，是jdk1.8的，它已经占用了/usr/bin/java 的这个软链接
因此你需要先删除这个软连接
rm -rf /usr/bin/java
然后重新创建 java 软链接到 /usr/bin/ 目录下
ln -s /usr/local/java/jdk-21.0.5/ /usr/bin/java
编辑系统配置文件
vi /etc/profile
按下 键盘 i 进入可编辑模式；按下shift + G 快速定位到文件结尾处
然后输入以下内容
export JAVA_HOME=/usr/bin/java
export PATH=$JAVA_HOME/bin:$PATH
输入完毕之后，按下 esc，进入到 不可编辑状态； 按下shift + ：(shift + 冒号)；此时在键盘输入字母 wq(wq表示保存退出的意思)
激活配置文件
source /etc/profile
验证java安装是否成功
java --version
若输出以下内容
[root@localhost java]# java -version
java version "21.0.5" 2024-10-15 LTS
Java(TM) SE Runtime Environment (build 21.0.5+9-LTS-239)
Java HotSpot(TM) 64-Bit Server VM (build 21.0.5+9-LTS-239, mixed mode, sharing)
表示JDK21安装环境成功
可以输入 javac 再次进行验证
[root@localhost java]# javac
Usage: javac <options> <source files>
where possible options include:
@<filename> Read options and filenames from file
-Akey[=value] Options to pass to annotation processors
--add-modules <module>(,<module>)*
Root modules to resolve in addition to the initial modules,
or all modules on the module path if <module> is ALL-MODULE-PATH.
--boot-class-path <path>, -bootclasspath <path>
Override location of bootstrap class files
--class-path <path>, -classpath <path>, -cp <path>
Specify where to find user class files and annotation processors
-d <directory> Specify where to place generated class files
-deprecation
Output source locations where deprecated APIs are used
--enable-preview
Enable preview language features.
To be used in conjunction with either -source or --release.
-encoding <encoding> Specify character encoding used by source files
-endorseddirs <dirs> Override location of endorsed standards path
-extdirs <dirs> Override location of installed extensions
-g Generate all debugging info
-g:{lines,vars,source} Generate only some debugging info
-g:none Generate no debugging info
-h <directory>
Specify where to place generated native header files
--help, -help, -? Print this help message
--help-extra, -X Print help on extra options
-implicit:{none,class}
Specify whether to generate class files for implicitly referenced files
-J<flag> Pass <flag> directly to the runtime system
--limit-modules <module>(,<module>)*
Limit the universe of observable modules
--module <module>(,<module>)*, -m <module>(,<module>)*
Compile only the specified module(s), check timestamps
--module-path <path>, -p <path>
Specify where to find application modules
--module-source-path <module-source-path>
Specify where to find input source files for multiple modules
--module-version <version>
Specify version of modules that are being compiled
-nowarn Generate no warnings
-parameters
Generate metadata for reflection on method parameters
-proc:{none,only,full}
Control whether annotation processing and/or compilation is done.
-processor <class1>[,<class2>,<class3>...]
Names of the annotation processors to run;
bypasses default discovery process
--processor-module-path <path>
Specify a module path where to find annotation processors
--processor-path <path>, -processorpath <path>
Specify where to find annotation processors
-profile <profile>
Check that API used is available in the specified profile.
This option is deprecated and may be removed in a future release.
--release <release>
Compile for the specified Java SE release.
Supported releases:
8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21
-s <directory> Specify where to place generated source files
--source <release>, -source <release>
Provide source compatibility with the specified Java SE release.
Supported releases:
8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21
--source-path <path>, -sourcepath <path>
Specify where to find input source files
--system <jdk>|none Override location of system modules
--target <release>, -target <release>
Generate class files suitable for the specified Java SE release.
Supported releases:
8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21
--upgrade-module-path <path>
Override location of upgradeable modules
-verbose Output messages about what the compiler is doing
--version, -version Version information
-Werror Terminate compilation if warnings occur
以上就是 linux 虚拟机安装 JDK21的操作过程
题外话：
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