java中获取系统属性以及环境变量

java中获取系统属性以及环境变量

System.getEnv（）和System.getProperties（）的差别

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。环境变量产生很多其它的全局效应，由于它们不仅对Java 子进程可见，并且对于定义它们的进程的全部子进程都是可见的。在不同的操作系统上，它们的语义有细微的区别，比方，不区分大写和小写。由于这些原因，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。环境变量应该在须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（比方 PATH）。

代码例如以下：

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);

              }

       }

 

输入例如以下：

ANT_HOME:D:/program/devel/ant

PROCESSOR_ARCHITECTURE:x86

LOGONSERVER://RJ-WEIJIANJUN

HOMEDRIVE:C:

CATALINA_HOME:D:/program/server/Tomcat5.5

DXSDK_DIR:d:/Program
Files/Microsoft DirectX SDK (August 2008)/

VS80COMNTOOLS:C:/Program
Files/Microsoft Visual Studio 8/Common7/Tools/

SESSIONNAME:Console

HOMEPATH:/Documents and
Settings/Administrator

TMP:C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp

windir:C:/WINDOWS

PROCESSOR_IDENTIFIER:x86 Family
6 Model 15 Stepping 13, GenuineIntel

VS90COMNTOOLS:e:/Program
Files/Microsoft Visual Studio 9.0/Common7/Tools/

SystemDrive:C:

USERPROFILE:C:/Documents and
Settings/Administrator

PATHEXT:.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH

CommonProgramFiles:C:/Program
Files/Common Files

NUMBER_OF_PROCESSORS:2

ComSpec:C:/WINDOWS/system32/cmd.exe

COMPUTERNAME:RJ-WEIJIANJUN

OS:Windows_NT

USERNAME:Administrator

CLIENTNAME:Console

TEMP:C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp

USERDOMAIN:RJ-WEIJIANJUN

ALLUSERSPROFILE:C:/Documents
and Settings/All Users

lib:C:/Program Files/SQLXML
4.0/bin/

PROCESSOR_LEVEL:6

SystemRoot:C:/WINDOWS

ClusterLog:C:/WINDOWS/Cluster/cluster.log

APPDATA:C:/Documents and
Settings/Administrator/Application Data

Path: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/bin

JAVA_HOME:C:/Program
Files/Java/jdk1.6.0_07

FP_NO_HOST_CHECK:NO

PROCESSOR_REVISION:0f0d

ProgramFiles:C:/Program Files

下面是property的输出：

--------------------------------------

java.runtime.name:Java(TM) 2
Runtime Environment, Standard Edition

sun.boot.library.path:D:/Program
Files/MyEclipse 6.5/jre/bin

java.vm.version:1.5.0_11-b03

java.vm.vendor:Sun Microsystems
Inc.

java.vendor.url:http://java.sun.com/

path.separator:;

java.vm.name:Java HotSpot(TM)
Client VM

file.encoding.pkg:sun.io

sun.java.launcher:SUN_STANDARD

user.country:CN

sun.os.patch.level:Service Pack
2

java.vm.specification.name:Java
Virtual Machine Specification

user.dir:D:/dev/eclipse/mye65/workspace/jmx

java.runtime.version:1.5.0_11-b03

java.awt.graphicsenv:sun.awt.Win32GraphicsEnvironment

java.endorsed.dirs:D:/Program
Files/MyEclipse 6.5/jre/lib/endorsed

os.arch:x86

java.io.tmpdir:C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/

line.separator:

 

java.vm.specification.vendor:Sun
Microsystems Inc.

user.variant:

os.name:Windows 2003

sun.jnu.encoding:GBK

java.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/bin

java.specification.name:Java
Platform API Specification

java.class.version:49.0

sun.management.compiler:HotSpot
Client Compiler

os.version:5.2

user.home:C:/Documents and
Settings/Administrator

user.timezone:Asia/Shanghai

java.awt.printerjob:sun.awt.windows.WPrinterJob

file.encoding:GBK

java.specification.version:1.5

java.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/registry.jar

user.name:Administrator

java.vm.specification.version:1.0

java.home:D:/Program
Files/MyEclipse 6.5/jre

sun.arch.data.model:32

user.language:zh

java.specification.vendor:Sun
Microsystems Inc.

awt.toolkit:sun.awt.windows.WToolkit

java.vm.info:mixed mode

java.version:1.5.0_11

java.ext.dirs:D:/Program
Files/MyEclipse 6.5/jre/lib/ext

sun.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/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:windows

sun.cpu.isalist:pentium_pro+mmx
pentium_pro pentium+mmx pentium i486 i386 i86

个人觉得比較重要的系统属性：

java.home：Java 安装文件夹 (比方D:/JavaStudio/jdk15/jre)

java.class.path：Java 类路径

java.vm.version：Java虚拟机版本(比方：1.5.0-b64）

java.version：Java版本(比方：1.5.0)

os.name：操作系统的名称(比方：Windows XP)

os.version：操作系统的版本号(比方：Windows XP 的版本号为5.1)

user.home：用户的主文件夹 (比方：C:/Documents and Settings/zhangsan)

user.name：当前username

user.country：当前用户所属国家

user.dir：用户的当前工作文件夹

比較重要的环境变量（Windows操作系统）：

%COMPUTERNAME%     返回计算机的名称。

%COMSPEC%     返回命令行解释器可运行程序的准确路径。

%WINDIR%    返回操作系统文件夹的位置。

%OS%     返回操作系统的名称。Windows 2000 将操作系统显示为 Windows_NT。

%PATH%    指定可运行文件的搜索路径。

%USERDOMAIN%    返回包括用户帐户的域的名称。

%USERNAME%    返回当前登录的用户的名称。

以下是一篇在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
doesn't 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 name

os = System.getProperty("os.name").toLowerCase();

// according to OS set the command to execute

if(os.startsWith("windows"))

{

cmd = "cmd /c SET";

}

else

{

cmd="env";

}

try

{

//execute the command and get the result in the form of InputStream

Process p = Runtime.getRuntime().exec(cmd);

//parse the InputStream data

InputStreamReader isr = new InputStreamReader(p.getInputStream());

commandResult= new BufferedReader(isr);

}

catch (Exception e)

{

System.out.println("OSEnvironment.class error: " + cmd +
":" + e);

}

}

/**

* This method is used to get the path of the given enviornment variable. This

* method tries to simulates the System.getenv() which is deprecated on java
1.4.2

*

* @param String - name of the environment variable

* @param String - default value

* @return

*/

public static String getenv(String envName,String defaultValue)

{

String line = null;

try

{

while ((line = commandResult.readLine()) != null)

{

if(line.indexOf(envName)>-1)

{

return line.substring(line.indexOf(envName)+envName.length()+1);

}

}

return defaultValue;

}

catch (Exception e)

{

return defaultValue;

}

}

public static void
main(String args[])

{

System.out.println(TestRoot.getenv("CLASSPATH",""));

}

}