ubuntu更改java为openjdk

修改环境变量

vim ~/.bashrc

export JAVA_HOME=/usr/lib/jvm/java-7-sun 
export JRE_HOME=${JAVA_HOME}/jre 
export CLASSPATH=:${JAVA_HOME}/lib:${JRE_HOME}/lib 
export PATH=${JAVA_HOME}/bin:$PATH

一定要加上:$PATH否则会覆盖系统path

source ~/.bashrc

配置默认使用的JDK版本

sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/java-7-sun/bin/java 300 
sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/java-7-sun/bin/javac 300 
sudo update-alternatives --install /usr/bin/jar jar /usr/lib/jvm/java-7-sun/bin/jar 300

sudo update-alternatives --config java  

输入1，2，3代表默认使用的jdk版本

java -version

java version “1.7.0_03”
Java(TM) SE Runtime Environment (build 1.7.0_03-b04)

Java HotSpot(TM) Server VM (build 22.1-b02, mixed mode)