查看现有jdk
命令:rpm -qa | grep jdk
结果：java-1.6.0-openjdk-1.6.0.0-1.45.1.11.1.el6.i686
卸载现有jdk
命令yum -y remove java-1.6.0-openjdk-1.6.0.0-1.45.1.11.1.el6.i686
如果出现找不到openjdk source的话，那么还可以这样卸载
命令yum -y remove java java-1.6.0-openjdk-1.6.0.0-1.45.1.11.1.el6.i686
等一段时间就Complete了。
下载Sun的JDK。我下载的是
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jdk-6u37-linux-i586-rpm.bin
如果是64位系统的话，要下载：
jdk-6u37-linux-x64-rpm.bin
之类的64位专用的包
到/usr目录下创建java目录，将下载的文件放到/usr/java目录下
先将这个文件变为可执行文件（chmod 777） ：
[root@dc-01 java]# chmod 777 jdk-6u37-linux-i586-rpm.bin
然后执行这个文件件进行安装：
[root@dc-01 java]# ./jdk-6u37-linux-i586-rpm.bin
Unpacking...
Checksumming...
Extracting...
inflating: jdk-6u37-linux-i586.rpm
inflating: sun-javadb-common-10.6.2-1.1.i386.rpm
inflating: sun-javadb-core-10.6.2-1.1.i386.rpm
inflating: sun-javadb-client-10.6.2-1.1.i386.rpm
inflating: sun-javadb-demo-10.6.2-1.1.i386.rpm
inflating: sun-javadb-docs-10.6.2-1.1.i386.rpm
inflating: sun-javadb-javadoc-10.6.2-1.1.i386.rpm
Preparing... ########################################### [100%]
1:jdk ########################################### [100%]
Unpacking JAR files...
rt.jar...
jsse.jar...
charsets.jar...
tools.jar...
localedata.jar...
plugin.jar...
javaws.jar...
deploy.jar...
Installing JavaDB
Preparing... ########################################### [100%]
1:sun-javadb-common ########################################### [ 17%]
2:sun-javadb-core ########################################### [ 33%]
3:sun-javadb-client ########################################### [ 50%]
4:sun-javadb-demo ########################################### [ 67%]
5:sun-javadb-docs ########################################### [ 83%]
6:sun-javadb-javadoc ########################################### [100%]
Java(TM) SE Development Kit 6 successfully installed.
Product Registration is FREE and includes many benefits:
* Notification of new versions, patches, and updates
* Special offers on Oracle products, services and training
* Access to early releases and documentation
Product and system data will be collected. If your configuration
supports a browser, the JDK Product Registration form will
be presented. If you do not register, none of this information
will be saved. You may also register your JDK later by
opening the register.html file (located in the JDK installation
directory) in a browser.
For more information on what data Registration collects and
how it is managed and used, see:
http://java.sun.com/javase/registration/JDKRegistrationPrivacy.html
Press Enter to continue.....
这个时候按一下回车。
出现Done .
至此安装结束。
接下来配置JDK：
vi /etc/profile打开profile文件，在profile文件的末尾加上：
JAVA_HOME=/usr/java/jdk1.6.0_37
PATH=$JAVA_HOME/bin:$PATH
CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export JAVA_HOME
export PATH
export CLASSPATH
保存并关闭profile文件，执行source /etc/profile命令让修改生效。
运行下java-version 看一下java版本 ：
[root@dc-01 java]# java -version
java version "1.6.0_37"
Java(TM) SE Runtime Environment (build 1.6.0_37-b06)
Java HotSpot(TM) Client VM (build 20.12-b01, mixed mode, sharing)
[root@dc-01 java]#
================================================
至此，整个安装过程完毕。