由于Linux开发厂商不同，不同开发厂商的Linux版本的操作细节也不同。今天来说说CentOS下JDK的安装：方法一：手动解压JDK压缩包，然后设置环境变量1.在/usr/目录下创建java目录[root@localhost~]#mkdir/usr/java[root@localhost~]#cd/usr/java2.下载jdk，然后解压[root@localhostjava]#curl-Ohttp://download.oracle.com/otn-pub/java/jdk/7u79-b15/jdk-7u79-linux-x64.tar.gz[root@localhostjava]#tar-zxvfjdk-7u79-linux-x64.tar.gz3.设置环境变量[root@localhostjava]#vi/etc/profile在配置文件中添加如下内容：#setjavaenvironmentJAVA_HOME=/usr/java/jdk1.7.0_79JRE_HOME=/usr/java/jdk1.7.0_79/jreCLASS_PATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/libPATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/binexportJAVA_HOMEJRE_HOMECLASS_PATHPATH让修改生效：[root@localhostjava]#source/etc/profile4.验证JDK是否有效[root@localhostjava]#java-versionjavaversion"1.7.0_79"Java(TM)SERuntimeEnvironment(build1.7.0_79-b15)JavaHotSpot(TM)64-BitServerVM(build24.79-b02,mixedmode)方法2：用yum安装JDK1。查看yum库中有哪些jdk版本（暂时只找到openjdk）[root@localhost~]#yumsearchjava|grepjdkldapjdk-javadoc.x86_64:Javadocforldapjdkjava-1.6.0-openjdk.x86_64:OpenJDKRuntimeEnvironmentjava-1.6.0-openjdk-demo.x86_64:OpenJDKDemosjava-1.6.0-openjdk-devel.x86_64:OpenJDKDevelopmentEnvironmentjava-1.6.0-openjdk-JvaumentAPI.18_java64:OpenJDKDemosjava-1.6.0-openjdk-devel.x86_64:OpenJDKDevelopmentEnvironmentjava-1.6.0-openjdk-JvaumentAPI.18_java64:0-openjdk-src.x86_64:OpenJDKSourceBundlejava-1.7.0-openjdk.x86_64:OpenJDKRuntimeEnvironmentjava-1.7.0-openjdk-demo.x86_64:OpenJDKDemosjava-1.7.0-openjdk-devel.x86_64:OpenJDKDevelopmentEnvironment1.dk-0.0java-javadoc.noarch：OpenJDKAPIDocumentationjava-1.7.0-openjdk-src.x86_64：OpenJDKSourceBundlejava-1.8.0-openjdk.x86_64：OpenJDKRuntimeEnvironmentjava-1.8.0-openjdk-demo.x86_64：OpenJDKDemosjava-1.8.0-openjdk6_64：openjdk6_develOpenJDKDevelopmentEnvironmentjava-1.8.0-openjdk-headless.x86_64:OpenJDKRuntimeEnvironmentjava-1.8.0-openjdk-javadoc.noarch:OpenJDKAPIDocumentationjava-1.8.0-openjdk-src.x86_64:OpenJDKSourceBundleldapjdk.x86_64:TheMozillaLDAPJavaSDK2.选择版本，进行安装//选择1.7版本安装[root@localhost~]#yuminstalljava-1.7.0-openjdk//安装后默认安装目录为：/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.75.x86_643。设置环境变量[root@localhost~]#vi/etc/profile在profile文件中加入如下内容#setjavaenvironmentJAVA_HOME=/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.75.x86_64JRE_HOME=$JAVA_HOME/jreCLASS_PATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/libPATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/binexportJAVA_HOMEJRE_HOMECLASS_PATHPATH让修改生效[root@localhostjava]#来源/etc/profile4。验证（方法同上）方法三：用rpm安装JDK1。下载rpm安装文件[root@localhost~]$curl-Ohttp://download.oracle.com/otn-pub/java/jdk/7u79-b15/jdk-7u79-linux-x64.rpm2。使用rpm命令安装[root@localhost~]#rpm-ivhjdk-7u79-linux-x64.rpm3。设置环境变量[root@localhostjava]#vi/etc/profile在打开的profile文件中添加如下内容：#setjavaenvironmentJAVA_HOME=/usr/java/jdk1.7.0_79JRE_HOME=/usr/java/jdk1.7.0_79/jreCLASS_PATH=。:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/libPATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/binexportJAVA_HOMEJRE_HOMECLASS_PATHPATH让修改生效[root@localhostjava]#source/etc/个人资料4。验证（同上方法）注：与yum安装类似，无需设置环境变量即可运行java命令。rpm安装方式默认会把jdk安装到/usr/java/jdk1.7.0_79，然后通过三层链接链接到/usr/bin。具体链接如下：[root@localhost~]#cd/bin[root@localhostbin]#ll|grepjavarwxrwxrwx.1rootroot25Mar2811:24jar->/usr/java/default/bin/jarlrwxrwxrwx.1rootroot26Mar2811:24java->/usr/java/default/bin/javarwxrwxrwx.1rootroot27Mar2811:24javac->/usr/java/defaultbin/javaclrwxrwxrwx.1rootroot29Mar2811:24javadoc->/usr/java/default/bin/javadoclrwxrwxrwx.1rootroot28Mar2811:24javaws->/usr默认/bin/javawslrwxrwxrwx.1rootroot30Mar2811:24jcontrol->/usr/java/默认jcontrol[root@localhostbin]#cd/usr/java/[root@localhostjava]#lltotal4lrwxrwxrwx.1rootroot16Mar2811:24default->/usr/java/latestdrwxr-xr-x.8rootroot4096Mar2811:24jdk1.7.0_79lrwxrwxrwx.1root1:21Mar281>usr/java/jdk1.7.0_79方法四：使用apt-get在Ubuntu上安装JDK1。查看apt库中的jdk版本root@Itble:~#apt-cachesearchjava|grepjdkdefault-jdk-StandardJavaorJavacompatibleDevelopmentKitdefault-jdk-doc-StandardJava或JavacompatibleDevelopmentKit(文档)gcj-4.6-jdk-gcjandclasspathdevelopmenttoolsforJava(TM)gcj-jdk-gcjandclasspathdevelopmenttoolsforJava(TM)openjdk-6-dbg-JavaruntimebasedonOpenJDK(debuggingsymbols)openjdk-6-demo-JavaruntimebasedonOpenJDK(demosandexdevelopj6)JDK)文档openjdk-6-jdk-OpenJDKDevelopmentKit(JDK)openjdk-6-jre-lib-OpenJDKJavaruntime(architectureindependentlibraries)openjdk-6-source-OpenJDKDevelopmentKit(JDK)sourcefilesopenjdk-7-dbg-JavaruntimebasedonOpenJDK(debuggingsymbols)openjdk-7-demo-JavaruntimebasedonOpenJDK(demosandexamples)openjdk-7-doc-OpenJDKDevelopmentKit(JDK)documentationopenjdk-7-jdk-OpenJDKDevelopmentKit(JDK)openjdk-7-source-OpenJDKDevelopmentKit(JDK)sourcefilesuwsgi-plugin-jvm-openjdk-6-JavapluginforuWSGI(OpenJDK6)uwsgi-6plugin-jwsgi-openjdk-6-JWSGIpluginforuWSGI(OpenJDK6)openjdk-6-jre-OpenJDKJavaruntime,usingHotspotJITopenjdk-6-jre-headless-OpenJDKJavaruntime,usingHotspotJIT(headless)openjdk-7-jre-OpenJDKJavaruntime,usingHotspotJITopenjdk-7-jre-headless-OpenJDKJavaruntime,usingHotspotJIT(headless)openjdk-7-jre-lib-OpenJDKJavaruntime(architectureindependentlibraries)2.选择要安装的版本root@Itble:~#apt-getinstallopenjdk-7-jdk3.设置环境变量root@Itble:~#vi/etc/profile在打开的profile文件中添加如下内容#setjavaenvironmentJAVA_HOME=/usr/lib/jvm/java-1.7.0-openjdk-amd64JRE_HOME=$JAVA_HOME/jreCLASS_PATH=。:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/libPATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/binexportJAVA_HOMEJRE_HOMECLASS_PATHPATH让修改生效root@Itble:~#source/etc/个人资料4。验证（方法同上）
