linux上使用yum安装openjdk1.8
JDK 环境变量
使用yum查找jdk: yum search java|grep jdk
# yum search java|grep jdk ldapjdk-javadoc.noarch : Javadoc for ldapjdk java-1.6.0-openjdk.x86_64 : OpenJDK Runtime Environment java-1.6.0-openjdk-demo.x86_64 : OpenJDK Demos java-1.6.0-openjdk-devel.x86_64 : OpenJDK Development Environment java-1.6.0-openjdk-javadoc.x86_64 : OpenJDK API Documentation java-1.6.0-openjdk-src.x86_64 : OpenJDK Source Bundle java-1.7.0-openjdk.x86_64 : OpenJDK Runtime Environment java-1.7.0-openjdk-accessibility.x86_64 : OpenJDK accessibility connector java-1.7.0-openjdk-demo.x86_64 : OpenJDK Demos java-1.7.0-openjdk-devel.x86_64 : OpenJDK Development Environment java-1.7.0-openjdk-headless.x86_64 : The OpenJDK runtime environment without java-1.7.0-openjdk-javadoc.noarch : OpenJDK API Documentation java-1.7.0-openjdk-src.x86_64 : OpenJDK Source Bundle java-1.8.0-openjdk.i686 : OpenJDK Runtime Environment java-1.8.0-openjdk.x86_64 : OpenJDK Runtime Environment java-1.8.0-openjdk-accessibility.i686 : OpenJDK accessibility connector java-1.8.0-openjdk-accessibility.x86_64 : OpenJDK accessibility connector java-1.8.0-openjdk-accessibility-debug.i686 : OpenJDK accessibility connector java-1.8.0-openjdk-accessibility-debug.x86_64 : OpenJDK accessibility connector java-1.8.0-openjdk-debug.i686 : OpenJDK Runtime Environment with full debug on java-1.8.0-openjdk-debug.x86_64 : OpenJDK Runtime Environment with full debug on java-1.8.0-openjdk-demo.i686 : OpenJDK Demos java-1.8.0-openjdk-demo.x86_64 : OpenJDK Demos java-1.8.0-openjdk-demo-debug.i686 : OpenJDK Demos with full debug on java-1.8.0-openjdk-demo-debug.x86_64 : OpenJDK Demos with full debug on java-1.8.0-openjdk-devel.i686 : OpenJDK Development Environment java-1.8.0-openjdk-devel.x86_64 : OpenJDK Development Environment java-1.8.0-openjdk-devel-debug.i686 : OpenJDK Development Environment with full java-1.8.0-openjdk-devel-debug.x86_64 : OpenJDK Development Environment with java-1.8.0-openjdk-headless.i686 : OpenJDK Runtime Environment java-1.8.0-openjdk-headless.x86_64 : OpenJDK Runtime Environment java-1.8.0-openjdk-headless-debug.i686 : OpenJDK Runtime Environment with full java-1.8.0-openjdk-headless-debug.x86_64 : OpenJDK Runtime Environment with full java-1.8.0-openjdk-javadoc.noarch : OpenJDK API Documentation java-1.8.0-openjdk-javadoc-debug.noarch : OpenJDK API Documentation for packages java-1.8.0-openjdk-javadoc-zip.noarch : OpenJDK API Documentation compressed in java-1.8.0-openjdk-javadoc-zip-debug.noarch : OpenJDK API Documentation java-1.8.0-openjdk-src.i686 : OpenJDK Source Bundle java-1.8.0-openjdk-src.x86_64 : OpenJDK Source Bundle java-1.8.0-openjdk-src-debug.i686 : OpenJDK Source Bundle for packages with java-1.8.0-openjdk-src-debug.x86_64 : OpenJDK Source Bundle for packages with java-11-openjdk.i686 : OpenJDK Runtime Environment 11 java-11-openjdk.x86_64 : OpenJDK Runtime Environment 11 java-11-openjdk-debug.i686 : OpenJDK Runtime Environment 11 with full debug on java-11-openjdk-debug.x86_64 : OpenJDK Runtime Environment 11 with full debug on java-11-openjdk-demo.i686 : OpenJDK Demos 11 java-11-openjdk-demo.x86_64 : OpenJDK Demos 11 java-11-openjdk-demo-debug.i686 : OpenJDK Demos 11 with full debug on java-11-openjdk-demo-debug.x86_64 : OpenJDK Demos 11 with full debug on java-11-openjdk-devel.i686 : OpenJDK Development Environment 11 java-11-openjdk-devel.x86_64 : OpenJDK Development Environment 11 java-11-openjdk-devel-debug.i686 : OpenJDK Development Environment 11 with full java-11-openjdk-devel-debug.x86_64 : OpenJDK Development Environment 11 with java-11-openjdk-headless.i686 : OpenJDK Headless Runtime Environment 11 java-11-openjdk-headless.x86_64 : OpenJDK Headless Runtime Environment 11 java-11-openjdk-headless-debug.i686 : OpenJDK Runtime Environment with full java-11-openjdk-headless-debug.x86_64 : OpenJDK Runtime Environment with full java-11-openjdk-javadoc.i686 : OpenJDK 11 API documentation java-11-openjdk-javadoc.x86_64 : OpenJDK 11 API documentation java-11-openjdk-javadoc-debug.i686 : OpenJDK 11 API documentation for packages java-11-openjdk-javadoc-debug.x86_64 : OpenJDK 11 API documentation for packages java-11-openjdk-javadoc-zip.i686 : OpenJDK 11 API documentation compressed in java-11-openjdk-javadoc-zip.x86_64 : OpenJDK 11 API documentation compressed in java-11-openjdk-javadoc-zip-debug.i686 : OpenJDK 11 API documentation compressed java-11-openjdk-javadoc-zip-debug.x86_64 : OpenJDK 11 API documentation java-11-openjdk-jmods.i686 : JMods for OpenJDK 11 java-11-openjdk-jmods.x86_64 : JMods for OpenJDK 11 java-11-openjdk-jmods-debug.i686 : JMods for OpenJDK 11 with full debug on java-11-openjdk-jmods-debug.x86_64 : JMods for OpenJDK 11 with full debug on java-11-openjdk-src.i686 : OpenJDK Source Bundle 11 java-11-openjdk-src.x86_64 : OpenJDK Source Bundle 11 java-11-openjdk-src-debug.i686 : OpenJDK Source Bundle for packages with debug java-11-openjdk-src-debug.x86_64 : OpenJDK Source Bundle 11 for packages with ldapjdk.noarch : The Mozilla LDAP Java SDK
执行安装命令：yum install java-1.8.0-openjdk
安装成功后，默认安装路径在/usr/lib/jvm/下边，
如/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.144-0.b01.el6_9.x86_64
查看安装路径(如下所示)：
which java
ls -lrt /usr/bin/java
[root@preproduct1 ~]# which java /usr/bin/java [root@preproduct1 ~]# echo $JAVA_HOME /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-1.el7_6.x86_64 [root@preproduct1 ~]# ls -lrt /usr/bin/java lrwxrwxrwx 1 root root 22 Feb 13 10:40 /usr/bin/java -> /etc/alternatives/java [root@preproduct1 ~]# ls -lrt /etc/alternatives/java lrwxrwxrwx 1 root root 73 Feb 13 10:40 /etc/alternatives/java -> /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-1.el7_6.x86_64/jre/bin/java [root@preproduct1 ~]# cd /usr/lib/jvm [root@preproduct1 /usr/lib/jvm]# ll total 4 lrwxrwxrwx 1 root root 26 Feb 13 10:44 java -> /etc/alternatives/java_sdk lrwxrwxrwx 1 root root 32 Feb 13 10:44 java-1.8.0 -> /etc/alternatives/java_sdk_1.8.0 lrwxrwxrwx 1 root root 40 Feb 13 10:44 java-1.8.0-openjdk -> /etc/alternatives/java_sdk_1.8.0_openjdk drwxr-xr-x 7 root root 4096 Feb 13 10:44 java-1.8.0-openjdk-1.8.0.191.b12-1.el7_6.x86_64 lrwxrwxrwx 1 root root 34 Feb 13 10:44 java-openjdk -> /etc/alternatives/java_sdk_openjdk lrwxrwxrwx 1 root root 21 Feb 13 10:40 jre -> /etc/alternatives/jre lrwxrwxrwx 1 root root 27 Feb 13 10:40 jre-1.8.0 -> /etc/alternatives/jre_1.8.0 lrwxrwxrwx 1 root root 35 Feb 13 10:40 jre-1.8.0-openjdk -> /etc/alternatives/jre_1.8.0_openjdk lrwxrwxrwx 1 root root 51 Feb 13 10:40 jre-1.8.0-openjdk-1.8.0.191.b12-1.el7_6.x86_64 -> java-1.8.0-openjdk-1.8.0.191.b12-1.el7_6.x86_64/jre lrwxrwxrwx 1 root root 29 Feb 13 10:40 jre-openjdk -> /etc/alternatives/jre_openjdk
验证java是否安装成功
查看java版本：java -versio
# java -version openjdk version "1.8.0_191" OpenJDK Runtime Environment (build 1.8.0_191-b12) OpenJDK 64-Bit Server VM (build 25.191-b12, mixed mode)
查看java是否可用：javac
# javac -bash: javac: command not found
错误原因：默认安装完只有运行环境，java安装目录下只有jre文件夹
安装开发环境yum install java-1.8.0-openjdk-devel.x86_64
安装完可看到java安装目录下出现bin、lib等文件夹:
[root@preproduct1 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-1.el7_6.x86_64]# l total 20 drwxr-xr-x 2 root root 4096 Feb 13 10:44 bin drwxr-xr-x 3 root root 4096 Feb 13 10:44 include drwxr-xr-x 4 root root 4096 Feb 13 10:40 jre drwxr-xr-x 3 root root 4096 Feb 13 10:44 lib drwxr-xr-x 2 root root 4096 Feb 13 10:44 tapset
再次输入javac说明安装成功
# javac
Usage: 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 use
-classpath <path> Specify where to find user class files and annotationocessors
-cp <path> Specify where to find user class files and annotationocessors
-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 compilat is done.
-processor <class1>[,<class2>,<class3>...] Names of the annotation processors ton; 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 imcitly 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 proe
-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
设置环境变量
修改/etc/profile文件：vi /etc/profile
在profile文件末尾新增如下内容：
#set java environment JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-1.el7_6.x86_64 JRE_HOME=$JAVA_HOME/jre CLASS_PATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin export JAVA_HOME JRE_HOME CLASS_PATH PATH
使环境变量生效：source /etc/profile
[root@preproduct1 /usr/lib/jvm]# cd /usr/lib/jvm [root@preproduct1 /usr/lib/jvm]# cd java-1.8.0-openjdk-1.8.0.191.b12-1.el7_6.x86_64/ [root@preproduct1 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-1.el7_6.x86_64]# source /etc/profile [root@preproduct1 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-1.el7_6.x86_64]# echo $JAVA_HOME /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-1.el7_6.x86_64
至此jdk安装成功
