This article mainly introduces how to install the JDK in the Linux environment, because in the Linux environment, Java is often inseparable, so the author will share with you the process of jdk1.8.
0、 We first have a clean Linux environment
Proceed as follows:
[ root@itheima ~]# cat /etc/redhat-release
CentOS Linux release 7.5.1804(Core)[root@itheima ~]# ll
Total amount 0
1、 Check the jdk version in the linux system
[ root@itheima ~]# java -version
Shown as follows:
openjdk version "1.8.0_161"
OpenJDK Runtime Environment(build 1.8.0_161-b14)
OpenJDK 64-Bit Server VM(build 25.161-b14, mixed mode)
2、 Check the jdk installation package under linux
[ root@itheima ~]# rpm -qa | grep java
or
[ root@itheima ~]# rpm -qa | grep jdk
Shown as follows:
python-javapackages-3.4.1-11.el7.noarch
java-1.8.0-openjdk-headless-1.8.0.161-2.b14.el7.x86_64
tzdata-java-2018c-1.el7.noarch
java-1.7.0-openjdk-1.7.0.171-2.6.13.2.el7.x86_64
java-1.8.0-openjdk-1.8.0.161-2.b14.el7.x86_64
javapackages-tools-3.4.1-11.el7.noarch
java-1.7.0-openjdk-headless-1.7.0.171-2.6.13.2.el7.x86_64
or
copy-jdk-configs-3.3-2.el7.noarch
java-1.8.0-openjdk-headless-1.8.0.161-2.b14.el7.x86_64
java-1.7.0-openjdk-1.7.0.171-2.6.13.2.el7.x86_64
java-1.8.0-openjdk-1.8.0.161-2.b14.el7.x86_64
java-1.7.0-openjdk-headless-1.7.0.171-2.6.13.2.el7.x86_64
3、 Uninstall openjdk first (4 files in total)
[ root@itheima ~]# rpm -e --nodeps java-1.8.0-openjdk-headless-1.8.0.161-2.b14.el7.x86_64
[ root@itheima ~]# rpm -e --nodeps java-1.7.0-openjdk-1.7.0.171-2.6.13.2.el7.x86_64
[ root@itheima ~]# rpm -e --nodeps java-1.8.0-openjdk-1.8.0.161-2.b14.el7.x86_64
[ root@itheima ~]# rpm -e --nodeps java-1.7.0-openjdk-headless-1.7.0.171-2.6.13.2.el7.x86_64
After the deletion, you can use the rpm -qa | grep java or rpm -qa | grep jdk command to check whether it is deleted
[ root@itheima ~]# rpm -qa | grep java
python-javapackages-3.4.1-11.el7.noarch
tzdata-java-2018c-1.el7.noarch
javapackages-tools-3.4.1-11.el7.noarch
[ root@itheima ~]# rpm -qa | grep jdk
copy-jdk-configs-3.3-2.el7.noarch
[ root@itheima ~]#
4、 Install new Oracle JDK1.8
Use the command: cd /usr/local/ to enter the local directory, and use the ll (two lowercase L) command or the ls command (ll itself is not a command, just an alias for the ls -l command) All non-implicit files in the current directory. If you want to see the hidden (starting with ., such as: .test.txt) file information, you can use ll -a to view, as follows:
[ root@itheima ~]# cd /usr/local/[root@itheima local]# ll
Total amount 0
drwxr-xr-x.2 root root 64 Nov 112018 bin
drwxr-xr-x.2 root root 64月112018 etc
drwxr-xr-x.2 root root 64月112018 games
drwxr-xr-x.2 root root 64 Nov 112018 include
drwxr-xr-x.2 root root 64 Nov 112018 lib
drwxr-xr-x.2 root root 64 Nov 112018 lib64
drwxr-xr-x.2 root root 64 Nov 112018 libexec
drwxr-xr-x.2 root root 64 Nov 112018 sbin
drwxr-xr-x.5 root root 49 Nov 200:50 share
drwxr-xr-x.2 root root 64 Nov 112018 src
After entering the local directory, use the mkdir java command to create a java directory to store your own jdk.
Extension: If you want to create multiple directories at the same level at one time, you can use mkdir brother1 brother2 (if you want to create more, just add it at the end, separated by spaces). If you want to create a parent-child directory (parent/child) at once, you can create it by mkdir -p parent/child/grandson, as follows:
[ root@itheima local]# mkdir java
[ root@itheima local]# ll
Total amount 0
drwxr-xr-x.2 root root 64 Nov 112018 bin
drwxr-xr-x.2 root root 64月112018 etc
drwxr-xr-x.2 root root 64月112018 games
drwxr-xr-x.2 root root 64 Nov 112018 include
drwxr-xr-x.2 root root 611/819:01 java
drwxr-xr-x.2 root root 64 Nov 112018 lib
drwxr-xr-x.2 root root 64 Nov 112018 lib64
drwxr-xr-x.2 root root 64 Nov 112018 libexec
drwxr-xr-x.2 root root 64 Nov 112018 sbin
drwxr-xr-x.5 root root 49 Nov 200:50 share
drwxr-xr-x.2 root root 64 Nov 112018 src
5、 Use the SSH link tool SecureCRT to connect to the Linux system and open the SFTP session
Upload the downloaded jdk installation package jdk-8u191-linux-x64.tar.gz to the /usr/local/java directory of the Linux system
sftp> pwd
/root
sftp> cd /usr/local/java/
sftp> pwd
/usr/local/java
sftp> put -r "C:\Users\Bruce\Desktop\jdk-8u191-linux-x64.tar.gz"
Uploading jdk-8u191-linux-x64.tar.gz to /usr/local/java/jdk-8u191-linux-x64.tar.gz
100 % 187259KB 46814KB/s 00:00:04
C:\Users\Bruce\Desktop\jdk-8u191-linux-x64.tar.gz:191753373 bytes transferred in4seconds(46814 KB/s)
sftp> put -r "C:\Users\Bruce\Desktop\jdk-8u191-linux-x64.tar.gz"
Uploading jdk-8u191-linux-x64.tar.gz to /usr/local/java/jdk-8u191-linux-x64.tar.gz
100 % 187259KB 62419KB/s 00:00:03
C:\Users\Bruce\Desktop\jdk-8u191-linux-x64.tar.gz:191753373 bytes transferred in3seconds(62419 KB/s)
sftp>
After the transfer is complete, ll command to view
[ root@itheima java]# ll
Total amount 187260-rw-r--r--.1 root root 19175337311 month 817:07 jdk-8u191-linux-x64.tar.gz
[ root@itheima java]#
6、 Unzip the jdk-8u191-linux-x64.tar.gz installation package
[ root@itheima java]# tar -zxvf jdk-8u191-linux-x64.tar.gz
After decompression, the following appears:
............
jdk1.8.0_191/jre/lib/fontconfig.SuSE.10.properties.src
jdk1.8.0_191/jre/lib/fontconfig.SuSE.11.bfc
jdk1.8.0_191/jre/COPYRIGHT
jdk1.8.0_191/jre/THIRDPARTYLICENSEREADME-JAVAFX.txt
jdk1.8.0_191/jre/Welcome.html
jdk1.8.0_191/jre/README
jdk1.8.0_191/README.html
[ root@itheima java]# ll
Total amount 187260
drwxr-xr-x.710143245 October 620:55 jdk1.8.0_191
- rw-r--r--.1 root root 19175337311 month 817:07 jdk-8u191-linux-x64.tar.gz
At this time, the installation package is useless. I usually delete the installation package and delete the installation package through rm -f jdk-8u191-linux-x64.tar.gz.
Here -f means not to ask for deletion. If you don't add -f, it will ask you if you want to delete the installation package. If you are sure to delete, add -f.
If you want to delete a directory and there are directories or files in this directory, such as parent/child/grandson, you can use rm to delete all the directories and files (including parent) under the parent in such a directory -rf parent command can be deleted. rm -rf parent means to delete recursively without asking.
[ root@itheima java]# rm -rf jdk-8u191-linux-x64.tar.gz
[ root@itheima java]# ll
Total amount 0
drwxr-xr-x.710143245 October 620:55 jdk1.8.0_191
[ root@itheima java]#
7、 Set environment variables
Open the profile file disk to configure environment variables through the vim /etc/profile command
[ root@itheima java]# vim /etc/profile
After opening, press i to enter insert (insert) mode, add environment variables at the end of the file, the content is as follows:
JAVA_HOME=/usr/local/java/jdk1.8.0_191
JRE_HOME=/usr/local/java/jdk1.8.0_191/jre
CLASS_PATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib
PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin
export JAVA_HOME JRE_HOME CLASS_PATH PATH
After adding, save and exit. There are two commands for saving and exiting. The first is: hold down the shift key and then double-press z (this is what I often use because it is convenient and fast), the second is :wq command, there is a command to exit without saving :q! Note: The above three commands are all in non-insert mode (in insert mode, press the Esc key in the upper left corner of the keyboard to exit insert mode, which is wrong Insert mode).
8、 After saving, enter: source /etc/profile command to make the environment variable just configured take effect
[ root@itheima java]# source /etc/profile
[ root@itheima java]#
9、 Test whether the jdk is installed successfully
Enter the javac command. If the following text appears, the compilation is successful (if the language you used when you installed centos7 was English, then the English formatted like this appears)
[ root@itheima java]# javac
usage: javac <options><source files>
among them,Possible options include:-g Generate all debugging information
- g:none does not generate any debugging information
- g:{lines,vars,source}Only generate some debugging information
- nowarn does not generate any warnings
- verbose prints messages about what the compiler is doing
- deprecation output the source location using the obsolete API
- classpath <path>Specify where to find user class files and annotation handlers
- cp <path>Specify where to find user class files and annotation handlers
- sourcepath <path>Specify where to find the input source file
- bootclasspath <path>Override the location of the boot file
- extdirs <table of Contents>Override the location of installed extensions
- endorseddirs <table of Contents>Override the location of the signature path
- proc:{none,only}Control whether to perform annotation processing and/Or compile.
- processor <class1>[,<class2>,<class3>...]The name of the annotation handler to run;Bypass the default search process
- processorpath <path>Specify where to find annotation handlers
- parameters generate metadata for reflection of method parameters
- d <table of Contents>Specify where to place the generated class files
- s <table of Contents>Specify where to place the generated source files
- h <table of Contents>Specify where to place the generated native header file
- implicit:{none,class}Specify whether to generate class files for implicit reference files
- encoding <coding> 指定源文件使用的字符coding
- source <Release> 提供与指定Release的源兼容性
- target <Release>Generate class files for specific VM versions
- profile <Configuration file> 请确保使用的 API 在指定的Configuration file中可用
- version version information
- help output a summary of standard options
- A keyword[=value]Options passed to the annotation handler
- X output a summary of non-standard options
- J<mark>Directly<mark>Passed to the runtime system
- Werror terminates compilation when warning
@< file name> 从文件读取选项和file name
[ root@itheima java]#
Or enter java -version
[ root@itheima java]# java -version
java version "1.8.0_191"Java(TM) SE Runtime Environment(build 1.8.0_191-b12)
Java HotSpot(TM)64-Bit Server VM(build 25.191-b12, mixed mode)[root@itheima java]#
If the above information appears, it means that your own jdk is completely installed successfully! ! !
Reference link:
https://blog.csdn.net/hui_2016/article/details/69941850
https://www.cnblogs.com/Dylansuns/p/6974272.html
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