# yum openjdk8
-查看JDK版本。
java -version
yum -y install java-1.8.0-openjdk-devel.x86_64
-查看JDK安装后的路径。
find /usr/lib/jvm -name 'java-1.8.0-openjdk-1.8.0*'
/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.372.b07-4.0.2.al9.x86_64
vim /etc/profile
JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.372.b07-4.0.2.al8.x86_64
PATH=$PATH:$JAVA_HOME/bin
CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export JAVA_HOME CLASSPATH PATH
source /etc/profile
# yum jdk11
如果存在JKD且当前版本低于11，则执行如下命令卸载原有的JDK。
rpm -qa | grep java | xargs rpm -e --nodeps
继续执行以下命令安装新版本JDK。
yum install -y java-11-openjdk
执行以下命令查看是否安装成功。
java -version
# JDK8: java -version
Ubuntu
add-apt-repository ppa:webupd8team/java
apt update
apt install -y oracle-java8-installer
apt install -y oracle-java8-set-default
CentOS
wget http://up.htmltoo.com/soft/java/jdk-8u361-linux-x64.rpm
yum localinstall -y jdk-8u131-linux-x64.rpm
每台机器JDK安装. # 每台服务器操作一次.
# 查找,卸载jdk
rpm -qa | grep jdk # 查找jdk
rpm -e jdk1.8-1.8.0_181-fcs.x86_64 # 卸载jdk
# 下载jdk并解压:
mkdir /usr/java
cd /usr/java
# 安装jdk https://www.oracle.com/java/technologies/downloads/ ihunter@vip.qq.com W~1
a. jdk20:
https://www.oracle.com/java/technologies/downloads/#java20
wget http://up.htmltoo.com/soft/java/jdk-20_linux-x64_bin.rpm
rpm -ivh jdk-20_linux-x64_bin.rpm
添加java环境变量（需root账号）:
vi /etc/profile
#java path
export JAVA_HOME=/usr/java/jdk-11.0.15.1/
export CLASSPATH=$:CLASSPATH:$JAVA_HOME/lib/
export PATH=$PATH:$JAVA_HOME/bin
source /etc/profile
b. jdk8:
https://www.oracle.com/java/technologies/downloads/#java8
wget http://up.htmltoo.com/soft/java/jdk-8u361-linux-x64.rpm
rpm -ivh jdk-8u361-linux-x64.rpm
添加java环境变量（需root账号）:
vi /etc/profile
#java path
export JAVA_HOME=/usr/java/default
export JRE_HOME=/usr/java/default/jre
PATH=$JAVA_HOME/bin:$PATH
CLASSPATH=.:$JAVA_HOME/lib/rt.jar
export JAVA_HOME PATH CLASSPATH
source /etc/profile
echo 'export JAVA_HOME=/usr/java/default' >> /etc/profile
echo 'export PATH=$PATH:$JAVA_HOME/bin' >> /etc/profile
source /etc/profile
c. jdk7: https://www.oracle.com/technetwork/java/javase/downloads/java-archive-downloads-javase7-521261.html
wget http://up.htmltoo.com/soft/java/jdk-7u80-linux-x64.rpm
rpm -ivh jdk-7u80-linux-x64.rpm
添加java环境变量（需root账号）:
vi /etc/profile
#java path
JAVA_HOME=/usr/java/default
JRE_HOME=/usr/java/default/jre
CLASS_PATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib
PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin
export JAVA_HOME JRE_HOME CLASS_PATH PATH
#java path
export M3_HOME=/opt/taobao/maven3
export JAVA_HOME=/usr/java/default
export JRE_HOME=/usr/java/default/jre
export CLASSPATH=.:$JAVA_HOME/jre/lib/rt.jar:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export PATH=$PATH:$M3_HOME:$JAVA_HOME/bin
source /etc/profile
# 验证java是否安装成功:
java -version # java version "*"
rpm -qa | grep jdk # java version "*"
# 如何查看jdk安装路径
java -verbose
d. win配置环境变量
1.电脑右键属性, 高级系统设置, 高级,环境变量, 系统变量,
2.新建: JAVA_HOME，C:\Program Files\Java\jdk
3.编辑: Path, %JAVA_HOME%\bin
4.如果是Win7系统，直接输入在最后面输入
;%JAVA_HOME%\bin;%JAVA_HOME%\jre\bin
5.生成 jre文件
-先进盘符,或者会出错
C:
-安装路径
cd C:\Program Files\Java\jdk\bin
jlink --module-path jmods --add-modules java.desktop --output jre
e. mysql-connector-java
https://repo1.maven.org/maven2/mysql/mysql-connector-java/
