如何分辨安裝的Java的diffarences - JDK或JRE

Question

當我執行的java.exe -version
兩個JDK和JRE說：SE運行時環境
有沒有其他辦法區分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) 

Answer 1

夠簡單...嘗試和：

javac.exec -version 

如果你得到一個消息，告訴版本，你有JDK。如果你有一條消息告訴你該命令沒有找到，你有JRE。

Answer 2

如果你看看安裝了jdk/jre的文件夾結構，你會發現在jdk/bin文件夾中有很多的二進制文件，比如java，javac，javap等等.JRE包括java但不是javac，javap等。我假設這是linux，並且您下載了壓縮存檔並提取了它。

但是，這不是唯一的區別，JDK是開發工具包，其中還包括JRE。如果你對運行java程序感興趣，那麼JRE就足夠了，但是如果有開發包括編譯，那麼JDK是必需的。還請參閱：What is the difference between JDK and JRE?

的倉文件夾結構JDK和JRE（例如）之間的差異：

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 

所以，如果你輸入javac而它的命令不能被識別，那麼這意味着JDK/bin不在PATH上。就那麼簡單。這並不意味着JDK未安裝在該主機上 - 它可能是 - 它只是JRE/bin在PATH中，而JDK/bin則不是。

Answer 3

當我在路徑

的javac

我得到執行我的箱子下面沒有JDK;

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 

因爲我有我的路徑中運行時，當我

Java的版本

我得到執行以下操作;

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) 

在我的Mac具有JDK的道路上，當我做的javac

$ 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 
... 

總之我跑javac，看看我有JDK激活。