java中获取系统属性以及环境变量.doc

java中获取系统属性以及环境变量System.getEnv（）和System.getProperties（）的区别从概念上讲，系统属性 和环境变量 都是名称与值之间的映射。两种机制都能用来将用户定义的信息传递给 Java 进程。环境变量产生更多的全局效应，因为它们不仅对Java 子进程可见，而且对于定义它们的进程的所有子进程都是可见的。在不同的操作系统上，它们的语义有细微的差别，比如，不区分大小写。因为这些原因，环境变量更可能有意料不到的副作用。最好在可能的地方使用系统属性。环境变量应该在需要全局效应的时候使用，或者在外部系统接口要求使用环境变量时使用（比如 PATH）。代码如下：public static void main(String args)Map m = System.getenv();for ( Iterator it = m.keySet().iterator(); it.hasNext(); )String key = (String ) it.next();String value = (String ) m.get(key);System.out.println(key +: +value);System.out.println( - );Properties p = System.getProperties();for ( Iterator it = p.keySet().iterator(); it.hasNext(); )String key = (String ) it.next();String value = (String ) p.get(key);System.out.println(key +: +value);输入如下：ANT_HOME:D:/program/devel/antPROCESSOR_ARCHITECTURE:x86LOGONSERVER:/RJ-WEIJIANJUNHOMEDRIVE:C:CATALINA_HOME:D:/program/server/Tomcat5.5DXSDK_DIR:d:/Program Files/Microsoft DirectX SDK (August 2008)/VS80COMNTOOLS:C:/Program Files/Microsoft Visual Studio 8/Common7/Tools/SESSIONNAME:ConsoleHOMEPATH:/Documents and Settings/AdministratorTMP:C:/DOCUME1/ADMINI1/LOCALS1/Tempwindir:C:/WINDOWSPROCESSOR_IDENTIFIER:x86 Family 6 Model 15 Stepping 13, GenuineIntelVS90COMNTOOLS:e:/Program Files/Microsoft Visual Studio 9.0/Common7/Tools/SystemDrive:C:USERPROFILE:C:/Documents and Settings/AdministratorPATHEXT:.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSHCommonProgramFiles:C:/Program Files/Common FilesNUMBER_OF_PROCESSORS:2ComSpec:C:/WINDOWS/system32/cmd.exeCOMPUTERNAME:RJ-WEIJIANJUNOS:Windows_NTUSERNAME:AdministratorCLIENTNAME:ConsoleTEMP:C:/DOCUME1/ADMINI1/LOCALS1/TempUSERDOMAIN:RJ-WEIJIANJUNALLUSERSPROFILE:C:/Documents and Settings/All Userslib:C:/Program Files/SQLXML 4.0/bin/PROCESSOR_LEVEL:6SystemRoot:C:/WINDOWSClusterLog:C:/WINDOWS/Cluster/cluster.logAPPDATA:C:/Documents and Settings/Administrator/Application DataPath:C:/WINDOWS/system32;C:/WINDOWS;C:/WINDOWS/System32/Wbem;C:/Program Files/Microsoft SQL Server/80/Tools/Binn/;C:/Program Files/Microsoft SQL Server/90/DTS/Binn/;C:/Program Files/Microsoft SQL Server/90/Tools/binn/;C:/Program Files/Microsoft SQL Server/90/Tools/Binn/VSShell/Common7/IDE/;C:/Program Files/Microsoft Visual Studio 8/Common7/IDE/PrivateAssemblies/;D:/program/devel/flex_sdk2/bin;D:/program/devel/ant/bin;C:/Program Files/Java/jdk1.6.0_07/bin;%JONAS_ROOT%/bin/nt;d:/program/devel/ant/binJAVA_HOME:C:/Program Files/Java/jdk1.6.0_07FP_NO_HOST_CHECK:NOPROCESSOR_REVISION:0f0dProgramFiles:C:/Program Files以下是property的输出：-:Java(TM) 2 Runtime Environment, Standard Editionsun.boot.library.path:D:/Program Files/MyEclipse 6.5/jre/binjava.vm.version:1.5.0_11-b03java.vm.vendor:Sun Microsystems Inc.java.vendor.url:/path.separator:;:Java HotSpot(TM) Client VMfile.encoding.pkg:sun.iosun.java.launcher:SUN_STANDARDuser.country:CNsun.os.patch.level:Service Pack 2:Java Virtual Machine Specificationuser.dir:D:/dev/eclipse/mye65/workspace/jmxjava.runtime.version:1.5.0_11-b03java.awt.graphicsenv:sun.awt.Win32GraphicsEnvironmentjava.endorsed.dirs:D:/Program Files/MyEclipse 6.5/jre/lib/endorsedos.arch:x86java.io.tmpdir:C:/DOCUME1/ADMINI1/LOCALS1/Temp/line.separator:java.vm.specification.vendor:Sun Microsystems Inc.user.variant::Windows 2003sun.jnu.encoding:GBKjava.library.path:D:/Program Files/MyEclipse 6.5/jre/bin;.;C:/WINDOWS/system32;C:/WINDOWS;C:/WINDOWS/system32;C:/WINDOWS;C:/WINDOWS/System32/Wbem;C:/Program Files/Microsoft SQL Server/80/Tools/Binn/;C:/Program Files/Microsoft SQL Server/90/DTS/Binn/;C:/Program Files/Microsoft SQL Server/90/Tools/binn/;C:/Program Files/Microsoft SQL Server/90/Tools/Binn/VSShell/Common7/IDE/;C:/Program Files/Microsoft Visual Studio 8/Common7/IDE/PrivateAssemblies/;D:/program/devel/flex_sdk2/bin;D:/program/devel/ant/bin;C:/Program Files/Java/jdk1.6.0_07/bin;%JONAS_ROOT%/bin/nt;d:/program/devel/ant/:Java Platform API Specificationjava.class.version:49.0piler:HotSpot Client Compileros.version:5.2user.home:C:/Documents and Settings/Administratoruser.timezone:Asia/Shanghaijava.awt.printerjob:sun.awt.windows.WPrinterJobfile.encoding:GBKjava.specification.version:1.5java.class.path:D:/dev/eclipse/mye65/workspace/jmx/bin;D:/program/lib/jmx/jmxtools.jar;D:/program/lib/log/commons-logging-1.1.1.jar;D:/program/lib/log/log4j-1.2.15.jar;D:/program/lib/registry/:Administratorjava.vm.specification.version:1.0java.home:D:/Program Files/MyEclipse 6.5/jresun.arch.data.model:32user.language:zhjava.specification.vendor:Sun Microsystems Inc.awt.toolkit:sun.awt.windows.WT:mixed modejava.version:1.5.0_11java.ext.dirs:D:/Program Files/MyEclipse 6.5/jre/lib/extsun.boot.class.path:D:/Program Files/MyEclipse 6.5/jre/lib/rt.jar;D:/Program Files/MyEclipse 6.5/jre/lib/i18n.jar;D:/Program Files/MyEclipse 6.5/jre/lib/sunrsasign.jar;D:/Program Files/MyEclipse 6.5/jre/lib/jsse.jar;D:/Program Files/MyEclipse 6.5/jre/lib/jce.jar;D:/Program Files/MyEclipse 6.5/jre/lib/charsets.jar;D:/Program Files/MyEclipse 6.5/jre/classesjava.vendor:Sun Microsystems Inc.file.separator:/java.vendor.url.bug:/cgi-bin/bugreport.cgisun.io.unicode.encoding:UnicodeLittlesun.cpu.endian:littlesun.desktop:windowssun.cpu.isalist:pentium_pro+mmx pentium_pro pentium+mmx pentium i486 i386 i86个人认为比较重要的系统属性：java.home：Java 安装目录 (比如D:/JavaStudio/jdk15/jre)java.class.path：Java 类路径java.vm.version：Java虚拟机版本号(比如：1.5.0-b64）java.version：Java版本号(比如：1.5.0)：操作系统的名称(比如：Windows XP)os.version：操作系统的版本(比如：Windows XP 的版本为5.1)user.home：用户的主目录 (比如：C:/Documents and Settings/zhangsan)：当前用户名user.country：当前用户所属国家user.dir：用户的当前工作目录比较重要的环境变量（Windows操作系统）：%COMPUTERNAME% 返回计算机的名称。%COMSPEC% 返回命令行解释器可执行程序的准确路径。%WINDIR% 返回操作系统目录的位置。%OS% 返回操作系统的名称。Windows 2000 将操作系统显示为 Windows_NT。%PATH% 指定可执行文件的搜索路径。%USERDOMAIN% 返回包含用户帐户的域的名称。%USERNAME% 返回当前登录的用户的名称。下面是一篇在jdk1.4中得到环境变量的方法：Access user defined environment variable inside the java program with jdk1.4 In JDK 1.4 System.getenv() is deprecated. (In JDK 1.5 it is un-deprected again.) The getProperty method is now the correspoding method to get the variables. For example: System.getProperty(java.class.path,). But it doesnt work for user defined environment variable. This problem can be solved by using the following code: import java.io.BufferedReader;import java.io.InputStreamReader;/* Environment class simulates the System.getenv() method which is deprecated* on java 1.4.2* author v-josp*/public class TestRoot /result of all enviornment variables private static BufferedReader commandResult; static String cmd = null;String os = null;/getting the OS nameos = System.getProperty().toLowerCase();/ according to OS set the command to executeif(os.startsWith(windows)cmd = cmd /c SET;else cmd=env;try /execute the command and get the result in the form of InputStreamProcess p = Runtime.getRuntime().exec(cmd);/parse the InputStream data InputStreamReader isr = new Input