取得系统属性

package javasecurity;
import java.lang.*;
import java.security.*;
class GetProps
{
public static void main(String[] args)
{
String s;
try
{
System.out.println("About to get os.name property value");
//获得系统名称
s = System.getProperty("os.name", "not specified");
System.out.println(
"The name of your operating system is: "+s);
System.out.println(
"About to get java.version property value");
//获得JVM版本
s = System.getProperty("java.version", "not specified");
System.out.println(
"  The version of the JVM you are running is: " + s);
System.out.println("About to get user.home property value");
//获得用户缺省路径
s = System.getProperty("user.home", "not specified");
System.out.println("Your user home directory is: " + s);
System.out.println("About to get java.home property value");
//获得JVM缺省路径
s = System.getProperty("java.home", "not specified");
System.out.println("Your JRE installation directory is: "+s);
}
catch (Exception e)
{
System.err.println("Caught exception " + e.toString());
}
}
}