CentOS8.2安装Java 14.0.2的教程详解

[root@nfsclient ~]# dnf -y install java-11-openjdk java-11-openjdk-devel
Last metadata expiration check: 0:29:58 ago on Wed 09 Dec 2020 10:25:45 PM CST.
Dependencies resolved.
==============================================================================================================================
 Package              Architecture   Version                    Repository      Size
==============================================================================================================================
Installing:
 java-11-openjdk          x86_64      1:11.0.9.11-0.el8_2              AppStream      251 k
 java-11-openjdk-devel       x86_64      1:11.0.9.11-0.el8_2              AppStream      3.4 M
Installing dependencies:
 copy-jdk-configs          noarch      3.7-1.el8                   AppStream      27 k
 java-11-openjdk-headless      x86_64      1:11.0.9.11-0.el8_2              AppStream      40 M
 javapackages-filesystem      noarch      5.3.0-1.module_el8.0.0+11+5b8c10bd       AppStream      30 k
 lksctp-tools            x86_64      1.0.18-3.el8                  base        100 k
 ttmkfdir              x86_64      3.0.9-54.el8                  AppStream      62 k
 tzdata-java            noarch      2020d-1.el8                  AppStream      190 k
 xorg-x11-fonts-Type1        noarch      7.5-19.el8                   AppStream      522 k
Enabling module streams:
 javapackages-runtime                201801

Transaction Summary
==============================================================================================================================

[root@nfsclient ~]# java --version
openjdk 11.0.9 2020-10-20 LTS
OpenJDK Runtime Environment 18.9 (build 11.0.9+11-LTS)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.9+11-LTS, mixed mode, sharing)

# verify to create test program
[root@nfsclient ~]# cat >/tmp/java_test.java<<EOF
class java_test {
  public static void main(String[] args) {
    System.out.println("Hello Java World !");
  }
}
EOF

[root@dlp ~]# javac java_test.java
[root@dlp ~]# java java_test
Hello Java World !

如果你从CentOS官方存储库中安装了多个版本的Java，你可以用其他的方法来切换它们。

[root@nfsclient ~]# java --version
openjdk 11.0.5 2019-10-15 LTS
OpenJDK Runtime Environment 18.9 (build 11.0.5+10-LTS)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.5+10-LTS, mixed mode, sharing)
[root@dlp ~]# javac --version
javac 11.0.5

[root@nfsclient tmp]# dnf -y install jdk-14.0.2_linux-x64_bin.rpm

[root@nfsclient tmp]# java --version
java 14.0.2 2020-07-14
Java(TM) SE Runtime Environment (build 14.0.2+12-46)
Java HotSpot(TM) 64-Bit Server VM (build 14.0.2+12-46, mixed mode, sharing)

[root@nfsclient tmp]# cat >/etc/profile.d/jdk14.sh <<EOF
export JAVA_HOME=/usr/java/default
export PATH=\$PATH:\$JAVA_HOME/bin
EOF

To use Java Home, source the file.

[root@nfsclient tmp]# source /etc/profile.d/jdk14.sh

测试Java安装。
为了测试我们的Java安装，让我们创建一个简单的html文件。创建一个test.java文件，其内容如下

[root@nfsclient ~]# cat >/tmp/HelloWorld.java<<EOF
public class HelloWorld {
	public static void main(String[] args) {
	System.out.println(“Hello, world”);
	}
}
EOF

[root@nfsclient ~]# cat >/tmp/java_test01.java<<EOF
class java_test {
  public static void main(String[] args) {
    System.out.println("Hello Java World !");
  }
}
EOF

[root@nfsclient ~]#javac java_test01.java
[root@nfsclient ~]# java java_test01
Hello Java World !

如果你从CentOS官方存储库中安装了多个版本的Java，你可以用其他的方法来切换它们。

[root@nfsclient tmp]# alternatives --config java

There are 2 programs which provide 'java'.

 Selection  Command
-----------------------------------------------
  1      java-11-openjdk.x86_64 (/usr/lib/jvm/java-11-openjdk-11.0.9.11-0.el8_2.x86_64/bin/java)
*+ 2      /usr/java/jdk-14.0.2/bin/java

Enter to keep the current selection[+], or type selection number: 2

[root@nfsclient ~]#alternatives --config javac

[root@nfsclient ~]# alternatives --install /usr/bin/javac javac /usr/java/jdk-14.0.2/bin/javac 100
[root@nfsclient tmp]# alternatives --config javac

There are 2 programs which provide 'javac'.

 Selection  Command
-----------------------------------------------
  1      java-11-openjdk.x86_64 (/usr/lib/jvm/java-11-openjdk-11.0.9.11-0.el8_2.x86_64/bin/javac)
*+ 2      /usr/java/jdk-14.0.2/bin/javac

Enter to keep the current selection[+], or type selection number: