Java:System.getProperty(“user.home") 返回“?"； [英] Java: System.getProperty("user.home") returns "?"

问题描述

我完全迷失在这个:System.getProperty("user.home") 和 System.getProperty("user.name") 返回一个问号?".

I'm completely lost on this one: System.getProperty("user.home") and System.getProperty("user.name") returns a questionmark "?".

System-Specs:
Kubuntu 9.04
Gnome 2.2.61
Java 1.5.0_16

我的测试用例是这样的:

My testcase looks like that:

$ more Test.java
class Test { public static void main( String[] args ) { System.out.println( System.getProperties() ); } }

结果是(添加换行符以提高可读性，替换公司名称和自己的名称):

The result is (added line-breaks for better readability, replaced company name and own name):

$ javac Test.java
$ java Test
{
java.runtime.name=Java(TM) 2 Runtime Environment, Standard Edition,
sun.boot.library.path=/home/MYCOMPANY/myname/apps/jdk1.5.0_16/jre/lib/i386,
java.vm.version=1.5.0_16-b02,
java.vm.vendor=Sun Microsystems Inc.,
java.vendor.url=http://java.sun.com/,
path.separator=:,
java.vm.name=Java HotSpot(TM) Server VM,
file.encoding.pkg=sun.io,
sun.java.launcher=SUN_STANDARD,
user.country=US,
sun.os.patch.level=unknown,
java.vm.specification.name=Java Virtual Machine Specification,
user.dir=/home/MYCOMPANY/myname/temp,
java.runtime.version=1.5.0_16-b02,
java.awt.graphicsenv=sun.awt.X11GraphicsEnvironment,
java.endorsed.dirs=/home/MYCOMPANY/myname/apps/jdk1.5.0_16/jre/lib/endorsed,
os.arch=i386,
java.io.tmpdir=/tmp,
line.separator=
,
java.vm.specification.vendor=Sun Microsystems Inc.,
os.name=Linux,
sun.jnu.encoding=UTF-8,
java.library.path=/home/MYCOMPANY/myname/apps/jdk1.5.0_16/jre/lib/i386/server:/home/MYCOMPANY/myname/apps/jdk1.5.0_16/jre/lib/i386:/home/MYCOMPANY/myname/apps/jdk1.5.0_16/jre/../lib/i386,
java.specification.name=Java Platform API Specification,
java.class.version=49.0,
sun.management.compiler=HotSpot Server Compiler,
os.version=2.6.28-15-generic,
user.home=?,
user.timezone=,
java.awt.printerjob=sun.print.PSPrinterJob,
file.encoding=UTF-8,
java.specification.version=1.5,
java.class.path=.,
user.name=?,
java.vm.specification.version=1.0,
java.home=/home/MYCOMPANY/myname/apps/jdk1.5.0_16/jre,
sun.arch.data.model=32,
user.language=en,
java.specification.vendor=Sun Microsystems Inc.,
java.vm.info=mixed mode,
java.version=1.5.0_16,
java.ext.dirs=/home/MYCOMPANY/myname/apps/jdk1.5.0_16/jre/lib/ext,
sun.boot.class.path=/home/MYCOMPANY/myname/apps/jdk1.5.0_16/jre/lib/rt.jar:/home/MYCOMPANY/myname/apps/jdk1.5.0_16/jre/lib/i18n.jar:/home/MYCOMPANY/myname/apps/jdk1.5.0_16/jre/lib/sunrsasign.jar:/home/MYCOMPANY/myname/apps/jdk1.5.0_16/jre/lib/jsse.jar:/home/MYCOMPANY/myname/apps/jdk1.5.0_16/jre/lib/jce.jar:/home/MYCOMPANY/myname/apps/jdk1.5.0_16/jre/lib/charsets.jar:/home/MYCOMPANY/myname/apps/jdk1.5.0_16/jre/classes,
java.vendor=Sun Microsystems Inc.,
file.separator=/,
java.vendor.url.bug=http://java.sun.com/cgi-bin/bugreport.cgi,
sun.io.unicode.encoding=UnicodeLittle,
sun.cpu.endian=little,
sun.desktop=gnome,
sun.cpu.isalist=
}

有人经历过吗?Java 在哪里寻找用户和主目录?我已经检查了正确设置的 HOME 环境变量.

Did someone ever experience that? Where is Java looking to find the user and home directory? I already checked the HOME environment variable which is set correctly.

推荐答案

这有点尴尬，但解决方案只是在 64 位系统上使用 64 位 JDK.我从旧机器上复制了所有内容，这也意味着 32 位 JDK，这就是问题所在.它在 64 位运行时按预期工作.

It's a bit embarrassing but the solution was simply to use a 64-bit JDK on a 64-bit system. I copied everything from my old machine, which meant also a 32-bit JDK, and this was the problem. It worked as expected with a 64-bit runtime.

抱歉打扰了.

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