先下载JDK

For 64 Bit:-

# cd /opt/

# wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" "http://download.oracle.com/otn-pub/java/jdk/7u75-b13/jdk-7u75-linux-x64.tar.gz"

For 32 Bit:-

# cd /opt/

# wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" "http://download.oracle.com/otn-pub/java/jdk/7u75-b13/jdk-7u75-linux-i586.tar.gz"

解压缩并移动到/opt下

# tar xzf jdk-7u75-linux-x64.tar.gz
# mv jdk1.7.0_75 /opt

设置为默认虚拟机

# cd /opt/jdk1.7.0_75/

# alternatives --install /usr/bin/java java /opt/jdk1.7.0_75/bin/java 2

# alternatives --config java

出现以下选项时选择4
There are 4 programs which provide 'java'.

  Selection    Command

-----------------------------------------------

*  1           /usr/lib/jvm/jre-1.6.0-openjdk/bin/java

 + 2           /opt/jdk1.7.0_60/bin/java

   3           /opt/jdk1.7.0_72/bin/java

   4           /opt/jdk1.7.0_75/bin/java

Enter to keep the current selection[+], or type selection number: 4 [Press Enter]

# alternatives --install /usr/bin/jar jar /opt/jdk1.7.0_75/bin/jar 2

# alternatives --install /usr/bin/javac javac /opt/jdk1.7.0_75/bin/javac 2

# alternatives --set jar /opt/jdk1.7.0_75/bin/jar

# alternatives --set javac /opt/jdk1.7.0_75/bin/javac 

现在可以试一下java的版本了,输出如下

# java -version

java version "1.7.0_75"

Java(TM) SE Runtime Environment (build 1.7.0_75-b13)

Java HotSpot(TM) 64-Bit Server VM (build 24.75-b04, mixed mode)

设置一下环境变量

cat >> /etc/profile.d/java7.sh << EOF

export JAVA_HOME=/opt/jdk1..0_75

export JRE_HOME=/opt/jdk1..0_75/jre

export PATH=\$PATH:/opt/jdk1..0_75/bin:/opt/jdk1..0_75/jre/bin

EOF

重开一下终端 env|grep HOME 就可以看见结果了