Maven中的Java_home [英] Java_home in Maven

问题描述

当我运行 mvn -version 时，我注意到 java_home 指向 .. .jdk \ jre （如下图所示）。
那是错的吗？它不应该指向 ... \ jdk.x.y.z （没有 \ jre ）？
如果是这样，我该如何重置它？ （在全局％java_home％指向 jdk 目录）

When I ran mvn -version, I noticed the java_home points to ...jdk\jre (as shown below). Is that wrong? Isn't it supposed to point to ...\jdk.x.y.z (without the \jre)? If so, how do I reset it? (In global %java_home% points to the jdk directory)

C:\Users\Owner>mvn -version
Apache Maven 2.2.1 (r801777; 2009-08-06 15:16:01-0400)
Java version: 1.7.0_17
Java home: C:\Program Files\Java\jdk1.7.0_17\jre
Default locale: en_US, platform encoding: Cp1252
OS name: "windows 7" version: "6.1" arch: "amd64" Family: "windows"

推荐答案

不，这没错。它指向JDK使用的JRE，这是它应该的。如果您在maven外打印 JAVA_HOME ，它应该打印正确：

No, it's not wrong. It is pointing to the JRE used by your JDK, which is what it's supposed to. If you print out JAVA_HOME outside maven, it should print correctly:

C:\>echo %JAVA_HOME%
C:\Program Files\Java\jdk1.7.0_07

C:\>mvn -version
Apache Maven 3.0.4 (r1232337; 2012-01-17 10:44:56+0200)
Maven home: C:\APPS\apache-maven-3.0.4\bin\..
Java version: 1.7.0_07, vendor: Oracle Corporation
Java home: C:\Program Files\Java\jdk1.7.0_07\jre
Default locale: en_US, platform encoding: Cp1252
OS name: "windows 7", version: "6.1", arch: "amd64", family: "windows"
C:\>

所以基本上JAVA_HOME需要指向JDK安装（maven需要tools.jar）但实际上是maven使用JDK中的jre来运行自己。

So basically JAVA_HOME needs to point to a JDK installation (maven needs the tools.jar) but maven actually uses the jre within the JDK to run itself.

当使用 mvn -version 时，maven使用java内部java。家庭财产，从源代码：

When using mvn -version, maven uses java internal java.home property, as can be seen from source code:

version.append( "Java home: " + System.getProperty( "java.home", "<unknown java home>" ) ).append( LS );

此属性与JAVA_HOME环境设置不同，所以它可能会欺骗你。它实际上是动态属性，显示哪个JRE正在运行您的代码。如果您编译并执行打印相同的Test.java测试类，您可以看到如果您的JAVA_HOME指向JDK，则java.home的值不等于您的JAVA_HOME。这是预期的。

This property is not the same thing as JAVA_HOME environment setting, so it might fool you. It is actually dynamic property showing you which JRE is running your code. If you compile and execute a Test.java test class printing the same, you can see that if your JAVA_HOME points to a JDK, the value of java.home is not equal to your JAVA_HOME. This is expected.

引用这个：

JAVA_HOME和java.home有什么区别？

What's the difference between JAVA_HOME and java.home?

JAVA_HOME是JDK安装目录，例如C：\ jdk5。这意味着将
设置为环境变量，并在Windows批处理文件或
Unix脚本中引用。我总是在Windows控制面板和.tcsh
文件中以及其他常见环境变量中使用它。一些Java
应用程序使用名称jdk.home来实现此目的，我认为
是一个更好的名称。但是JAVA_HOME从一开始就被使用，现在是
惯例。

JAVA_HOME is the JDK install directory, e.g., C:\jdk5. It's meant to be set as an environment variable and referenced in Windows batch files or Unix scripts. I always have it in my Windows Control Panel and .tcsh files,along with other common environment variables. Some Java applications use the name jdk.home for this purpose, which I think is a better name. But JAVA_HOME has been used since the beginning and is now a convention.

java.home是JRE安装目录，例如C：\ jdk5 \\ \\ jre，或
C：\Program Files\Java \ jre1.5.0_06。与JAVA_HOME不同，我从未见过
java.home作为环境变量。 java.home是一个内置的Java
系统属性，其值为JRE安装目录。由于所有
Java系统属性也作为Ant构建属性公开，因此
也可以在构建文件中使用$ {java.home}。

java.home is the JRE install directory, e.g., C:\jdk5\jre, or C:\Program Files\Java\jre1.5.0_06. Unlike JAVA_HOME, I never seen java.home as an environment variable. java.home is a build-in Java system property, whose value is the JRE install directory. Since all Java system properties are also exposed as Ant build properties, you can also use ${java.home} in build files.

jre.home会是一个更好的名字吗？也许吧，但我不认为Sun会以
来改变它。

Would jre.home be a better name? Maybe, but I don't think Sun will change it.

你可以看到maven在mvn上使用JAVA_HOME。 bat：

You can see that maven uses JAVA_HOME on mvn.bat:

:endInit
SET MAVEN_JAVA_EXE="%JAVA_HOME%\bin\java.exe"
..
%MAVEN_JAVA_EXE% %MAVEN_OPTS% -classpath %CLASSWORLDS_JAR% ..

如果你想确定，你可以在mvn.bat中注释掉@echo off语句，这样你就可以看到它正被使用。

And if you want to make sure, you can comment out "@echo off" statement in mvn.bat, so you can see that it is being used.

TL; DR：根据您提供的信息，您的配置是正确的，无需更改任何内容。

TL;DR: Based on the information you've given, your configuration is correct, no need to change anything.

编辑：多亏了这个帖子，还有关于这个令人困惑的问题，导致Maven版本3.5.4的输出更改。

thanks to this thread, there was also an issue about this being confusing, which resulted in change of output for Maven version 3.5.4.

这篇关于Maven中的Java_home的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！