2015-09-15 24 views
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当我打电话给方法System.getProperties();并打印它们时,它给出了一个带有键值对但没有设置属性的大列表 。 Java哪里得到 那些属性?System.getProperties的属性来自哪里?

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从Java虚拟机的实现中硬编码值的底层计算机的性能和组合初始化自己的'Properties'对象。 [本新闻组帖子](https://groups.google.com/forum/#!topic/comp.lang.java.help/-JBBUicGRH4)涵盖了相同的问题。 –

回答

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来自托管Java的操作系统(环境)。检查Oracle documentation

在属性中,我们检查了应用程序可以使用Properties对象来维护其配置的方式。 Java平台本身使用一个Properties对象来维护自己的配置。 System类维护一个Properties对象,该对象描述当前工作环境的配置。系统属性包括有关当前用户的信息,Java运行时的当前版本以及用于分隔文件路径名称组件的字符。


Key     Meaning 
----------------- -------------------------------------------------------------------------- 
"file.separator" Character that separates components of a file path. This is "/" on UNIX and "\" on Windows. 
"java.class.path" Path used to find directories and JAR archives containing class files. Elements of the class path are separated by a platform-specific character specified in the path.separator property. 
"java.home"   Installation directory for Java Runtime Environment (JRE) 
"java.vendor"  JRE vendor name 
"java.vendor.url" JRE vendor URL 
"java.version"  JRE version number 
"line.separator" Sequence used by operating system to separate lines in text files 
"os.arch"   Operating system architecture 
"os.name"   Operating system name 
"os.version"  Operating system version 
"path.separator" Path separator character used in java.class.path 
"user.dir"   User working directory 
"user.home"   User home directory 
"user.name"   User account name