CentOS7安装JAVA及环境搭建

环境安装

jdk安装（rpm安装）

1、如果系统有自带openjdk 则需要卸载

1.1 查看系统是否自带JDK

在终端输入命令 java -version 结果如下

[root@suzhongde ~]# java -version
java version "1.8.0_121"
Java(TM) SE Runtime Environment (build 1.8.0_121-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.121-b13, mixed mode)

1.2 查看相关java文件

在终端输入命令 rpm -qa | grep java

# 检查
[root@suzhongde ~]# rpm -qa|grep jdk
jdk1.8.0_121-1.8.0_121-fcs.x86_64

1.3 删除相关文件

# 卸载 -e --nodeps 强制删除
[root@suzhongde ~]# rpm -e --nodeps jdk1.8.0_121-1.8.0_121-fcs.x86_64

1.4 查看删除结果

在终端输入命令 java -version 出现以下结果表示删除成功

[root@suzhongde suzhongde]# java -version
-bash: /usr/bin/java: No such file or directory

2、tar下载地址OpenJDK JDK 18 Release-Candidate Builds

3、安装JDK

3.1 解压安装JDK

[root@suzhongde suzhongde]# tar -zxvf java1.8

4. 配置JDK环境变量

4.1 vim /etc/profile 在最后面添加如下配置

JAVA_HOME=/usr/java/jdk1.8.0_221-amd64
CLASSPATH=%JAVA_HOME%/lib:%JAVA_HOME%/jre/lib
PATH=$PATH:$JAVA_HOME/bin:$JAVA_HOME/jre/bin
export PATH CLASSPATH JAVA_HOME

4.2 让新增的环境变量生效:在终端输入source /etc/profile

4.3 在终端输入java出现如下结果代表配置成功

Usage: java [-options] class [args...]
           (to execute a class)
   or  java [-options] -jar jarfile [args...]
           (to execute a jar file)
where options include:
    -d32	  use a 32-bit data model if available
    -d64	  use a 64-bit data model if available
    -server	  to select the "server" VM
                  The default VM is server,
                  because you are running on a server-class machine.


    -cp <class search path of directories and zip/jar files>
    -classpath <class search path of directories and zip/jar files>
                  A : separated list of directories, JAR archives,
                  and ZIP archives to search for class files.
    -D<name>=<value>
                  set a system property
    -verbose:[class|gc|jni]
                  enable verbose output
    -version      print product version and exit
    -version:<value>
                  Warning: this feature is deprecated and will be removed
                  in a future release.
                  require the specified version to run
    -showversion  print product version and continue
    -jre-restrict-search | -no-jre-restrict-search
                  Warning: this feature is deprecated and will be removed
                  in a future release.
                  include/exclude user private JREs in the version search
    -? -help      print this help message
    -X            print help on non-standard options
    -ea[:<packagename>...|:<classname>]
    -enableassertions[:<packagename>...|:<classname>]
                  enable assertions with specified granularity
    -da[:<packagename>...|:<classname>]
    -disableassertions[:<packagename>...|:<classname>]
                  disable assertions with specified granularity
    -esa | -enablesystemassertions
                  enable system assertions
    -dsa | -disablesystemassertions
                  disable system assertions
    -agentlib:<libname>[=<options>]
                  load native agent library <libname>, e.g. -agentlib:hprof
                  see also, -agentlib:jdwp=help and -agentlib:hprof=help
    -agentpath:<pathname>[=<options>]
                  load native agent library by full pathname
    -javaagent:<jarpath>[=<options>]
                  load Java programming language agent, see java.lang.instrument
    -splash:<imagepath>
                  show splash screen with specified image
See http://www.oracle.com/technetwork/java/javase/documentation/index.html for more details.