linux 下卸载ｊｄｋ重新安装配置JDK

一、jdk1.4卸载

Redhat Enterprise 5 中自带安装了jdk1.4，在安装jdk1.6前，把jdk1.4卸载：

1. 首先查看系统自带的JDK版本：
[code="java"]
# java -version
java version "1.4.2"
gij (GNU libgcj) version 4.1.2 20080704 (Red Hat 4.1.2-48)

Copyright (C) 2006 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
[/code]
2. 确定JDK的具体版本号，然后将其卸载：
[code="java"]
# rpm -qa | grep jdk
# rpm -qa | grep gcj
libgcj-4.1.2-42.el5
java-1.4.2-gcj-compat-1.4.2.0-40jpp.115
[/code]
上面先确认jdk的具体版本号，然后使用rpm -e --nodeps命令删除上面查找的内容：

#rpm -e --nodeps java-1.4.2-gcj-compat-1.4.2.0-40jpp.115

Complete!

3. 再次检查JDK版本，卸载成功:
[code="java"]
# java -version

-bash: ./usr/bin/java: No such file or directory

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二、jdk1.6安装

下面开始手动安装the latest jdk1.6 version，jdk-6u33-linux-i586.bin

1. 给jdk-6u33-linux-i586.bin分配权限，具体的这里要给它可执行的权限
# chmod +x jdk-6u33-linux-i586.bin

2. 然后解压：./jdk-6u33-linux-i586.bin
# ./jdk-6u33-linux-i586.bin

3. 执行之后会有一堆agreement什么的，一路more下去。接着有个确认安装的，输入yes，然后回车。开始解压。一直到

Java(TM) SE Development Kit 6 successfully installed.
.........
Press Enter to continue.....
Done.

4. 解压后的文件如下所示：
# ls
jdk1.6.0_33 jdk-6u33-linux-i586.bin

5. 一般都将安装文件放在usr/local下，执行拷贝：
[code="java"]
# mv jdk1.6.0_33 /usr/local
# cd /usr/local
# ls
bin etc games include jdk1.6.0_33 lib libexec sbin share src
[/code]
6. jdk已经成功搬运到了/usr/local下，然后就是最后一步，设置环境变量了。

7. 这里有两种设置，一种是通过export设置临时生效，重启之后设置会丢失，一种是将设置写入/etc/profile文件中，可以一直生效。所以，最好的设置当然是写入文件中了。先执行下面命令：
# vi /etc/profile

8. 打开profile文件后输入i进入insert模式，在文件最后面添加如下内容。
export JAVA_HOME="/usr/local/jdk1.6.0_33"
export CLASS_PATH="$JAVA_HOME/lib:$JAVA_HOME/jre/lib"
export PATH=".:$PATH:$JAVA_HOME/bin"
然后esc，输入:wq,保存退出。

9. 然后需要设置让更改生效：
[code="java"]
# source /etc/profile
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当然，如果你喜欢重启的话，你reboot也可以。

10. 查看当前jdk版本。
[code="java"]
# java -version
java version "1.6.0_33"
Java(TM) SE Runtime Environment (build 1.6.0_33-b03)
Java HotSpot(TM) Client VM (build 20.8-b03, mixed mode, sharing)
[/code]

安装完毕！
==========================================================
另一种方法：
[code="sql"]
# yum remove java
Loaded plugins: rhnplugin, security
This system is not registered with RHN.
RHN support will be disabled.
Setting up Remove Process
Resolving Dependencies
--> Running transaction check
---> Package java-1.4.2-gcj-compat.i386 0:1.4.2.0-40jpp.115 set to be erased
--> Processing Dependency: java-gcj-compat for package: antlr
--> Processing Dependency: java-gcj-compat for package: antlr
--> Processing Dependency: java-gcj-compat >= 1.0.64 for package: gjdoc
--> Processing Dependency: java-gcj-compat >= 1.0.64 for package: gjdoc
--> Running transaction check
---> Package antlr.i386 0:2.7.6-4jpp.2 set to be erased
---> Package gjdoc.i386 0:0.7.7-12.el5 set to be erased
--> Finished Dependency Resolution

Dependencies Resolved

====================================================================================================================================
Package Arch Version Repository Size
====================================================================================================================================
Removing:
java-1.4.2-gcj-compat i386 1.4.2.0-40jpp.115 installed 441
Removing for dependencies:
antlr i386 2.7.6-4jpp.2 installed 2.5 M
gjdoc i386 0.7.7-12.el5 installed 1.7 M

Transaction Summary
====================================================================================================================================
Remove 3 Package(s)
Reinstall 0 Package(s)
Downgrade 0 Package(s)

Is this ok [y/N]: y
Downloading Packages:
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
Erasing : antlr 1/3
Erasing : gjdoc 2/3
Erasing : java-1.4.2-gcj-compat 3/3

Removed:
java-1.4.2-gcj-compat.i386 0:1.4.2.0-40jpp.115

Dependency Removed:
antlr.i386 0:2.7.6-4jpp.2 gjdoc.i386 0:0.7.7-12.el5

Complete!

[/code]