java 快速入门

oracle

账号: [e-mail]
密码: Java2019

mac

snowdreams1006@snowdreams1006deMacBook-Pro datax-web-2.1.2 % which java
/usr/bin/java

snowdreams1006@snowdreams1006deMacBook-Pro datax-web-2.1.2 % whereis java
/usr/bin/java

snowdreams1006@snowdreams1006deMacBook-Pro datax-web-2.1.2 % java -version

snowdreams1006@snowdreams1006deMacBook-Pro datax-web-2.1.2 % /usr/libexec/java_home -V
Matching Java Virtual Machines (1):
    1.8.0_261, x86_64:	"Java SE 8"	/Library/Java/JavaVirtualMachines/jdk1.8.0_261.jdk/Contents/Home

/Library/Java/JavaVirtualMachines/jdk1.8.0_261.jdk/Contents/Home

snowdreams1006@snowdreams1006deMacBook-Pro datax-web-2.1.2 % ls /Library/Java/JavaVirtualMachines/jdk1.8.0_261.jdk/Contents/Home

COPYRIGHT				jmc.txt
LICENSE					jre
README.html				legal
THIRDPARTYLICENSEREADME-JAVAFX.txt	lib
THIRDPARTYLICENSEREADME.txt		man
bin					release
include					src.zip
javafx-src.zip

# java
export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_261.jdk/Contents/Home
export CLASSPATH=$JAVA_HOME/lib/tools.jar:$JAVA_HOME/lib/dt.jar:.
export PATH=$JAVA_HOME/bin:$PATH:.

snowdreams1006@snowdreams1006deMacBook-Pro datax-web-2.1.2 % vim ~/.bash_profile
snowdreams1006@snowdreams1006deMacBook-Pro datax-web-2.1.2 % source ~/.bash_profile

snowdreams1006@snowdreams1006deMacBook-Pro datax-web-2.1.2 % echo $JAVA_HOME
/Library/Java/JavaVirtualMachines/jdk1.8.0_261.jdk/Contents/Home

yum

yum search java

yum list java*

yum install java-1.8.0-openjdk-devel.x86_64

java-1.8.0-openjdk.i686                     1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk.x86_64                   1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-accessibility.i686       1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-accessibility.x86_64     1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-demo.i686                1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-demo.x86_64              1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-devel.i686               1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-devel.x86_64             1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-headless.i686            1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-headless.x86_64          1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-javadoc.noarch           1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-javadoc-zip.noarch       1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-src.i686                 1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-src.x86_64               1:1.8.0.262.b10-0.el7_8      updates

export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.171-8.b10.el6_9.x86_64
export CLASSPATH=.:$JAVA_HOME/jre/lib/rt.jar:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export PATH=$PATH:$JAVA_HOME/bin

source  /etc/profile

java -version

tar.gz

mkdir /usr/local/java/

tar -zxvf jdk-8u171-linux-x64.tar.gz -C /usr/local/java/

vim /etc/profile

export JAVA_HOME=/usr/local/java/jdk1.8.0_171
export JRE_HOME=${JAVA_HOME}/jre
export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib
export PATH=${JAVA_HOME}/bin:$PATH

source /etc/profile

ln -s /usr/local/java/jdk1.8.0_171/bin/java /usr/bin/java

java -version

use

• check java

yum list installed | grep java

java-1.8.0-openjdk.x86_64             1:1.8.0.262.b10-0.el7_8         @updates  
java-1.8.0-openjdk-devel.x86_64       1:1.8.0.262.b10-0.el7_8         @updates  
java-1.8.0-openjdk-headless.x86_64    1:1.8.0.262.b10-0.el7_8         @updates  
javapackages-tools.noarch             3.4.1-11.el7                    @base     
python-javapackages.noarch            3.4.1-11.el7                    @base     
tzdata-java.noarch                    2020a-1.el7                     @updates

rpm -qa |grep -i jdk

copy-jdk-configs-3.3-10.el7_5.noarch
java-1.8.0-openjdk-headless-1.8.0.262.b10-0.el7_8.x86_64
java-1.8.0-openjdk-1.8.0.262.b10-0.el7_8.x86_64
java-1.8.0-openjdk-devel-1.8.0.262.b10-0.el7_8.x86_64

java -version

openjdk version "1.8.0_262"
OpenJDK Runtime Environment (build 1.8.0_262-b10)
OpenJDK 64-Bit Server VM (build 25.262-b10, mixed mode)

whereis java
java: /usr/bin/java /usr/lib/java /etc/java /usr/share/java /usr/share/man/man1/java.1.gz

which java
/usr/bin/java

echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin

echo $JAVA_HOME

• search java

[root@snowdreams1006 datax]# yum list java*|grep java-1.8.0-openjdk
Repository epel is listed more than once in the configuration
java-1.8.0-openjdk.i686                     1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk.x86_64                   1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-accessibility.i686       1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-accessibility.x86_64     1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-demo.i686                1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-demo.x86_64              1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-devel.i686               1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-devel.x86_64             1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-headless.i686            1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-headless.x86_64          1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-javadoc.noarch           1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-javadoc-zip.noarch       1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-src.i686                 1:1.8.0.262.b10-0.el7_8      updates
java-1.8.0-openjdk-src.x86_64               1:1.8.0.262.b10-0.el7_8      updates

• install/uninstall java

yum install java-1.8.0-openjdk-devel.x86_64 -y

yum remove java-1.8.0-openjdk*  -y 

• config java

ls -hltr /usr/bin/java

lrwxrwxrwx 1 root root 22 9月   7 20:54 /usr/bin/java -> /etc/alternatives/java

ls -hltr /etc/alternatives/java
lrwxrwxrwx 1 root root 73 9月   7 20:54 /etc/alternatives/java -> /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.262.b10-0.el7_8.x86_64/jre/bin/java

ls -hltr /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.262.b10-0.el7_8.x86_64/jre/bin/java
-rwxr-xr-x 1 root root 8.8K 8月   7 00:43 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.262.b10-0.el7_8.x86_64/jre/bin/java

env |grep JAVA_HOME
JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.262.b10-0.el7_8.x86_64

ls /usr/lib/jvm/
java
java-1.8.0
java-1.8.0-openjdk
java-1.8.0-openjdk-1.8.0.262.b10-0.el7_8.x86_64
java-openjdk
jre
jre-1.8.0
jre-1.8.0-openjdk
jre-1.8.0-openjdk-1.8.0.262.b10-0.el7_8.x86_64
jre-openjdk

vim /etc/profile

# java
export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.262.b10-0.el7_8.x86_64
export JRE_HOME=$JAVA_HOME/jre 
export CLASS_PATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib 
export PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin

source  /etc/profile

java -version

ref docs

• CentOS使用yum安装jdk
• CentOS 7 安装 JAVA环境（JDK 1.8）
• 在CentOS7.4中安装jdk的几种方法及配置环境变量
• 在macOS系统中 下载、安装、使用Java8