Java System类用法实战案例

本文实例讲述了Java System类用法。分享给大家供大家参考，具体如下：

一 使用System类访问系统属性

1 代码

import java.util.Map;public class SystemClassDemo{  public static void main(String[] args)  {    Map<String, String> env = System.getenv();  // 获得系统的环境变量    for (String name : env.keySet())    {      System.out.println(name + "=" + env.get(name));    }  }}

2 运行

......
ALLUSERSPROFILE=C:/ProgramData
PROCESSOR_ARCHITECTURE=AMD64
PSModulePath=C:/Program Files/WindowsPowerShell/Modules;C:/WINDOWS/system32/WindowsPowerShell/v1.0/Modules
SystemDrive=C:
USERNAME=cakin
ProgramFiles(x86)=C:/Program Files (x86)
FPS_BROWSER_USER_PROFILE_STRING=Default
PYTHONPATH=.;E:/Python/MySQLControler
PATHEXT=.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC
DriverData=C:/Windows/System32/Drivers/DriverData
......

二 打印当前虚拟机的所有环境变量和值

1 代码

import java.util.Enumeration;import java.util.Properties;public class SystemInfo{  public static void main(String[] args)  {    Properties sp = System.getProperties(); //获得当前虚拟机的环境属性    Enumeration e = sp.propertyNames(); //获得环境属性中所有的变量    //循环打印出当前虚拟机的所有环境属性的变量和值    while (e.hasMoreElements())    {      String key = (String) e.nextElement();      System.out.println(key + " = " + sp.getProperty(key));    }  }}

2 运行

......
user.variant =
os.name = Windows 10
sun.jnu.encoding = GBK
java.library.path = D:/Program/Java/jdk1.8.0_162/bin;C:/WINDOWS/Sun/Java/bin;C:/WINDOWS/system32;C:/WINDOWS;C:/ProgramData/Oracle/Java/javapath;C:/Program Files (x86)/Intel/iCLS Client/;C:/Program Files/Intel/iCLS Client/;C:/WINDOWS/system32;C:/WINDOWS;C:/WINDOWS/System32/Wbem;C:/WINDOWS/System32/WindowsPowerShell/v1.0/;C:/Program Files (x86)/Intel/Intel(R) Management Engine Components/DAL;C:/Program Files/Intel/Intel(R) Management Engine Components/DAL;C:/Program Files (x86)/Intel/Intel(R) Management Engine Components/IPT;C:/Program Files/Intel/Intel(R) Management Engine Components/IPT;D:/Program Files (x86)/scala/bin;D:/Program Files/nodejs/;C:/WINDOWS/System32/OpenSSH/;D:/Program Files/Git/cmd;C:/Users/cakin/AppData/Local/Microsoft/WindowsApps;D:/Program/hadoop-2.7.4/bin;D:/Program/Java/jdk1.8.0_162/bin;C:/Program Files/Microsoft VS Code/bin;D:/Program/apache-maven-3.5.3/bin;C:/Users/cakin/AppData/Roaming/npm;D:/Program/gradle-2.14/bin;D:/Programs/Fiddler;D:/Python27;D:/Python27/Scripts;D:/Anaconda3;D:/Anaconda3/Scripts;D:/Anaconda3/Library/bin;E:/Django/ComPerformance/venv/Lib/site-packages/django;d:/Program Files (x86)/Nmap;.
java.specification.name = Java Platform API Specification
java.class.version = 52.0
sun.management.compiler = HotSpot 64-Bit Tiered Compilers
os.version = 10.0
......

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