Linux安装java

1.下载

地址：

1	https://pan.baidu.com/s/1ykSB3dsaYR1ow1iaU3FScg&shfl=sharepset

2.查看

ls -lht

3.安装

创建安装目录
mkdir /usr/local/java/
    
cd /usr/local/java/
解压至安装目录
tar -zxvf jdk-8u144-linux-x64.tar.gz -C /usr/local/java/
tar -zxvf jdk-7u80-linux-x64.tar.gz -C /usr/local/java/
tar -zxvf jdk-8u251-linux-x64.tar.gz -C /usr/local/java/

4.配置

设置环境变量
vim /etc/profile
在末尾添加
export JAVA_HOME=/usr/local/java/jdk1.8.0_144
export JRE_HOME=${JAVA_HOME}/jre
export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib
export PATH=${JAVA_HOME}/bin:$PATH

在末尾添加
export JAVA_HOME=/usr/local/java/jdk1.7.0_80
export CLASSPATH=.:${JAVA_HOME}/jre/lib/rt.jar:${JAVA_HOME}/lib/dt.jar:${JAVA_HOME}/lib/tools.jar
export PATH=${JAVA_HOME}/bin


使环境变量生效
source /etc/profile
检查
java -version

5.切换JDK7和JDK8

设置环境变量
vim /etc/profile
在末尾添加
export CLASSPATH=.:${JAVA_HOME}/jre/lib/rt.jar:${JAVA_HOME}/lib/dt.jar:${JAVA_HOME}/lib/tools.jar
export PATH=${JAVA_HOME}/bin

使环境变量生效
source /etc/profile
检查
java -version


alternatives --install /usr/bin/java java /usr/local/java/jdk1.8.0_251/bin/java 1500
alternatives --install /usr/bin/java java /usr/local/java/jdk1.8.0_144/bin/java 1500
alternatives --install /usr/bin/java java /usr/local/java/jdk1.7.0_80/bin/java 1400

alternatives --remove java /usr/local/java/jdk1.8.0_144/bin/java
alternatives --remove java /usr/local/java/jdk1.7.0_80/bin/java

alternatives --config java

选1或选2
java -version