java 通过 System 获取系统 属性列表

Standard System Properties

Property Name	Description	Java Version
file.encoding	The character encoding for the default locale	1.1
file.encoding.pkg	The package that contains the converters that handle converting between local encodings and Unicode	1.1
file.separator	The platform-dependent file separator (e.g., "/" on UNIX, "\" for Windows)	1.0
java.class.path	CLASSHATH 环境变量的值	1.0
java.class.version	Java API 的版本号	1.0
java.compiler	The just-in-time compiler to use, if any. The java interpreter provided with the JDK initializes this property from the environment variable JAVA_COMPILER.	1.0
java.home	Java 被安装的路径	1.0
java.io.tmpdir	Java 创建的暂存文件路径	1.2
java.version	The version of the Java interpreter	1.0
java.vendor	A vendor-specific string	1.0
java.vendor.url	A vendor URL	1.0
line.separator	The platform-dependent line separator (e.g., "\n" on UNIX, "\r\n" for Windows)	1.0
os.name	操作系统的名字	1.0
os.arch	系统的架构	1.0
os.version	操作系统的版本	1.0
path.separator	The platform-dependent path separator (e.g., ":" on UNIX, "," for Windows)	1.0
user.dir	当属性被初始化后，当前的工作目录	1.0
user.home	当前用户的目录	1.0
user.language	The two-letter language code of the default locale	1.1
user.name	当前用户名	1.0
user.region	The two-letter country code of the default locale	1.1
user.timezone	默认的时区	1.1