[英]How to tell the diffarences of installed java - JDK or JRE
當我執行java.exe -version
JDK和JRE都說: SE運行時環境
還有其他方法可以區分JDK或JRE
C:\Program Files\Java\1.6.0_45\bin>java.exe -version
java version "1.6.0_45"
Java(TM) SE Runtime Environment (build 1.6.0_45-b06)
Java HotSpot(TM) 64-Bit Server VM (build 20.45-b01, mixed mode)
足夠簡單...嘗試並:
javac.exec -version
如果收到告訴版本的消息,則說明您擁有JDK。 如果有消息告訴您找不到該命令,則說明您擁有JRE。
如果您查看安裝了jdk / jre的文件夾結構,您會發現在jdk / bin文件夾中有相當多的二進制文件集合,例如java,javac,javap等。JRE將包含Java但不包含javac, javap等。我假設這是linux,並且您下載了壓縮歸檔文件並將其解壓縮。
但這不是唯一的區別,JDK是也包括JRE的開發套件。 如果您對運行Java程序感興趣,那么JRE就足夠了,但是如果有包括編譯在內的開發,那么就需要JDK。 還請參見: JDK和JRE有什么區別?
JDK和JRE之間的bin文件夾結構差異(例如):
對於JRE:
$ ll jre/bin/
total 452K
lrwxrwxrwx. 1 ec2-user ec2-user 8 Nov 18 18:27 ControlPanel -> jcontrol
drwxr-xr-x. 5 ec2-user ec2-user 4.0K Sep 17 20:42 ..
drwxr-xr-x. 2 ec2-user ec2-user 4.0K Sep 17 20:42 .
-rwxr-xr-x. 1 ec2-user ec2-user 7.6K Sep 17 20:42 java
-rwxr-xr-x. 1 ec2-user ec2-user 130K Sep 17 20:42 javaws
-rwxr-xr-x. 1 ec2-user ec2-user 6.2K Sep 17 20:42 jcontrol
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 jjs
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 keytool
-rwxr-xr-x. 1 ec2-user ec2-user 8.0K Sep 17 20:42 orbd
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 pack200
-rwxr-xr-x. 1 ec2-user ec2-user 7.9K Sep 17 20:42 policytool
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 rmid
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 rmiregistry
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 servertool
-rwxr-xr-x. 1 ec2-user ec2-user 8.0K Sep 17 20:42 tnameserv
-rwxr-xr-x. 1 ec2-user ec2-user 224K Sep 17 20:42 unpack200
對於JDK:
$ ll jdk/bin/
total 780K
lrwxrwxrwx. 1 ec2-user ec2-user 8 Nov 18 18:27 ControlPanel -> jcontrol
drwxr-xr-x. 8 ec2-user ec2-user 4.0K Sep 17 20:44 ..
drwxr-xr-x. 2 ec2-user ec2-user 4.0K Sep 17 20:42 .
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 appletviewer
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 extcheck
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 idlj
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 jar
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 jarsigner
-rwxr-xr-x. 1 ec2-user ec2-user 7.6K Sep 17 20:42 java
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 javac
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 javadoc
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 javah
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 javap
-rwxr-xr-x. 1 ec2-user ec2-user 1.8K Sep 17 20:42 java-rmi.cgi
-rwxr-xr-x. 1 ec2-user ec2-user 130K Sep 17 20:42 javaws
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 jcmd
-rwxr-xr-x. 1 ec2-user ec2-user 7.9K Sep 17 20:42 jconsole
-rwxr-xr-x. 1 ec2-user ec2-user 6.2K Sep 17 20:42 jcontrol
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 jdb
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 jdeps
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 jhat
-rwxr-xr-x. 1 ec2-user ec2-user 8.0K Sep 17 20:42 jinfo
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 jjs
-rwxr-xr-x. 1 ec2-user ec2-user 8.0K Sep 17 20:42 jmap
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 jps
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 jrunscript
-rwxr-xr-x. 1 ec2-user ec2-user 7.8K Sep 17 20:42 jsadebugd
-rwxr-xr-x. 1 ec2-user ec2-user 8.0K Sep 17 20:42 jstack
因此,如果您鍵入javac
並且無法識別該命令,則表明JDK/bin
不在PATH
。 就那么簡單。 這並不意味着未在該主機上安裝JDK(可能的話),只是JRE/bin
位於PATH中,而JDK/bin
沒有。
當我在沒有路徑的JDK的盒子上執行以下命令時
Java語言
我懂了
The term 'javac' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and
try again.
At line:1 char:6
+ javac <<<<
+ CategoryInfo : ObjectNotFound: (javac:String) [], CommandNotFoundException
+ FullyQualifiedErrorId : CommandNotFoundException
由於執行以下操作時我的路徑中有運行時
Java版本
我懂了
java version "1.8.0_20"
Java(TM) SE Runtime Environment (build 1.8.0_20-b26)
Java HotSpot(TM) 64-Bit Server VM (build 25.20-b23, mixed mode)
在我執行javac時在路徑上具有jdk的mac上
$ 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
...
總而言之,我運行javac
來查看JDK是否處於活動狀態。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.