sentos7安装jdk8

卸载

查看已经安装的jdk

[root@bogon jre]# rpm -qa|grep jdkjava-1.8.0-openjdk-headless-1.8.0.65-3.b17.el7.x86_64java-1.7.0-openjdk-1.7.0.91-2.6.2.3.el7.x86_64java-1.7.0-openjdk-headless-1.7.0.91-2.6.2.3.el7.x86_64java-1.8.0-openjdk-1.8.0.65-3.b17.el7.x86_64
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卸载命令

[root@bogon jre]# yum -y remove java-1.8.0-openjdk-headless-1.8.0.65-3.b17.el7.x86_64
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卸载完成之后Java命令不被识别

[root@bogon lib]# java -versionbash: java: command not found...
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安装

去官网下载jdk：http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html 
解压到安装目录

[root@bogon software]# tar -zxvf jdk-8u101-linux-x64.tar.gz -C /usr/local/java/
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安装完毕之后在/etc/profile文件末尾添加

[root@bogon software]# vim /etc/profileexport JAVA_HOME=/usr/local/java/jdk1.8.0_101export JRE_HOME=${JAVA_HOME}/jreexport CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/libexport PATH=${JAVA_HOME}/bin:$PATH
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使/etc/profile生效

[root@bogon jdk1.8.0_101]# source /etc/profile
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检测安装是否成功

[root@bogon jdk1.8.0_101]# java -versionjava version "1.8.0_101"Java(TM) SE Runtime Environment (build 1.8.0_101-b13)Java HotSpot(TM) 64-Bit Server VM (build 25.101-b13, mixed mode)[root@bogon jdk1.8.0_101]# javacUsage: javac <options> <source files>where possible options include:  -g                         Generate all debugging info  -g:none                    Generate no debugging info  -g:{lines,vars,source}     Generate only some debugging info  -nowarn                    Generate no warnings  -verbose                   Output messages about what the compiler is doing  -deprecation               Output source locations where deprecated APIs are used  -classpath <path>          Specify where to find user class files and annotation processors  -cp <path>                 Specify where to find user class files and annotation processors  -sourcepath <path>         Specify where to find input source files  -bootclasspath <path>      Override location of bootstrap class files  -extdirs <dirs>            Override location of installed extensions  -endorseddirs <dirs>       Override location of endorsed standards path  -proc:{none,only}          Control whether annotation processing and/or compilation is done.  -processor <class1>[,<class2>,<class3>...] Names of the annotation processors to run; bypasses default discovery process  -processorpath <path>      Specify where to find annotation processors  -parameters                Generate metadata for reflection on method parameters  -d <directory>             Specify where to place generated class files  -s <directory>             Specify where to place generated source files  -h <directory>             Specify where to place generated native header files  -implicit:{none,class}     Specify whether or not to generate class files for implicitly referenced files  -encoding <encoding>       Specify character encoding used by source files  -source <release>          Provide source compatibility with specified release  -target <release>          Generate class files for specific VM version  -profile <profile>         Check that API used is available in the specified profile  -version                   Version information  -help                      Print a synopsis of standard options  -Akey[=value]              Options to pass to annotation processors  -X                         Print a synopsis of nonstandard options  -J<flag>                   Pass <flag> directly to the runtime system  -Werror                    Terminate compilation if warnings occur  @<filename>                Read options and filenames from file