jdk源码升级

1.下载安装jdk8 tar.gz的包或者其他服务器的jdk8的包拷贝过来

2.将准备好的jdk8复制到/usr/local/

# mv jdk1.8.0_92  /usr/local/

3.添加路径到/etc/profile,保存

# vim /etc/profile

export JAVA_HOME=/usr/local/jdk1.8.0_92

export JAVA_BIN=/usr/local/jdk1.8.0_92/bin

export PATH=$PATH:$JAVA_HOME/bin

export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar

#source /etc/profile

4.执行以后发现还是java7的版本，那么需要把jdk8设置成默认的版本

# update-alternatives  --install /usr/bin/java  java /usr/local/jdk1.8.0_92/bin/java 300

# update-alternatives  --install /usr/bin/javac  javac /usr/local/jdk1.8.0_92/bin/javac 300

# update-alternatives --config java

5.再查询java的版本