Rhel6下JDK1.6.0_26的配置
紅帽子下JDK的配置比Ubuntu的要方便些，直接下載，解壓，配置環境變量就行了。
1）建立目錄/usr/java
將jdk-6u26-linux-i586-rpm.bin拷貝到RHEL下的/usr/java下。
2） 修改文件權限，執行chmod 755 jdk-6u26-linux-i586-rpm.bin
3） 開始安裝，執行./ jdk-6u26-linux-i586-rpm.bin
4） 設置環境變量，打開/etc/profile，在文件末尾，done與unset i之間加入如下環境變量配置
JAVA_HOME=/usr/java/jdk1.6.0_26
CLASSPATH=.:$JAVA_HOME/lib.tools.jar
PATH=$JAVA_HOME/bin:$PATH
export JAVA_HOME CLASSPATH PATH
5） 重啓終端
6） 驗證是否安裝成功，執行java –version，將顯示如下信息
java version "1.6.0_26"
Java(TM) SE Runtime Environment (build 1.6.0_26-b03)
Java HotSpot(TM) Client VM (build 20.1-b02, mixed mode, sharing)
PS：Redhat Enterprise Linux 6.4 安裝Oracle JDK替換OpenJDK
缺省java版本爲OpenJDK 1.7:
# java -version
java version "1.7.0_09-icedtea"
OpenJDK Runtime Environment (rhel-2.3.4.1.el6_3-x86_64)
OpenJDK 64-Bit Server VM (build 23.2-b09, mixed mode)
# update-alternatives --config java
There are 2 programs which provide 'java'.
Selection Command
-----------------------------------------------
*+ 1 /usr/lib/jvm/jre-1.7.0-openjdk.x86_64/bin/java
2 /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/java
安裝Oracle JDK 1.7:
# rpm -ivh /mnt/hgfs/pub/jdk-7u45-linux-x64.rpm
update-alternatives添加Oracle JDK 1.7:
# update-alternatives --install /usr/bin/java java /usr/java/jdk1.7.0_45/bin/java 1
更改缺省JDK版本:
# update-alternatives --config java
There are 3 programs which provide 'java'.
Selection Command
-----------------------------------------------
*+ 1 /usr/lib/jvm/jre-1.7.0-openjdk.x86_64/bin/java
2 /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/java
3 /usr/java/jdk1.7.0_45/bin/java
Enter to keep the current selection[+], or type selection number: 3
# java -version
java version "1.7.0_45"
Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
Java HotSpot(TM) 64-Bit Server VM (build 24.45-b08, mixed mode)