1. 檢查系統中的jdk版本
java -version
複製程式碼顯示：
openjdk version "1.8.0_102"
OpenJDK Runtime Environment (build 1.8.0_102-b14)
OpenJDK 64-Bit Server VM (build 25.102-b14, mixed mode)
複製程式碼2. 查詢自帶的openjdk
rpm -qa | grep -i java
複製程式碼顯示：
java-1.7.0-openjdk-1.7.0.111-2.6.7.8.el7.x86_64
java-1.8.0-openjdk-1.8.0.102-4.b14.el7.x86_64
java-1.8.0-openjdk-headless-1.8.0.102-4.b14.el7.x86_64
java-1.7.0-openjdk-headless-1.7.0.111-2.6.7.8.el7.x86_64
複製程式碼3. 解除安裝openjdk
rpm -e --nodeps java-1.7.0-openjdk-1.7.0.111-2.6.7.8.el7.x86_64
rpm -e --nodeps java-1.7.0-openjdk-headless-1.7.0.111-2.6.7.8.el7.x86_64
rpm -e --nodeps java-1.8.0-openjdk-1.8.0.102-4.b14.el7.x86_64
rpm -e --nodeps java-1.8.0-openjdk-headless-1.8.0.102-4.b14.el7.x86_64
複製程式碼或者使用
yum remove *openjdk*
複製程式碼之後再次輸入rpm -qa | grep java 檢視解除安裝情況
4. 檢查系統環境
//i686表示32位 x86_64表示是64位
[root@node3 kafka_2.12-1.1.0]# uname -a
Linux localhost 3.10.0-862.2.3.el7.x86_64 #1 SMP Wed May 9 18:05:47 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
複製程式碼5. 下載
mkdir -p /usr/local/java
tar zxvf ../software/jdk-8u77-linux-x64.tar.gz -C /usr/local/java
複製程式碼6. 配置環境變數
vi /etc/profile
複製程式碼注：如果修改當前使用者的環境變數 編輯~/.profile或~/.bashrc檔案即可，而不是/etc/profile。
在檔案最後新增如下配置：
JAVA_HOME=/usr/local/java/jdk1.8.0_161
export CLASSPATH=$:CLASSPATH:$JAVA_HOME/lib/
export PATH=$PATH:$JAVA_HOME/bin
複製程式碼重新載入配置檔案，使配置生效(su root)：
source /etc/profile
複製程式碼或
source ~/.bash_profile
複製程式碼7. 檢查是否安裝成功
檢視java安裝指令碼
java -version
複製程式碼顯示：
java version “1.8.0_161”
Java(TM) SE Runtime Environment (build 1.8.0_161-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.161-b12, mixed mode)
複製程式碼檢視執行引數
javac
複製程式碼顯示：
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 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
複製程式碼出現以上資訊則代表安裝成功。