Java 如何取得操作系统的属性

 import java.util.Enumeration;
import java.util.HashMap;
import java.util.Properties;
public class SystemProperties
{
public static String LINE_SEPARATOR = "line.separator";
public static String FILE_SEPARATOR = "file.separator";
public static String USER_LANGUAGE = "user.language";
public static String FILE_ENCODING = "file.encoding";
public static String OS_NAME = "os.name";
public static String USER_DIR = "user.dir";
public static String USER_COUNTRY = "user.country";

private static SystemProperties SystemPropertiesInstance = null;
//零长度的byte数组对象创建起来将比任何对象都经济,查看编译后的字节码：
//生成零长度的byte[]对象只需3条操作码，而Object lock = new Object()则需要7行操作码
private static byte[] lockObject = new byte[0];

private HashMap<String,String> ptHashtable = null;

private SystemProperties()
{
InitAllProperties();
}
public static SystemProperties newInstance()
{
synchronized(lockObject)
{
if(null == SystemPropertiesInstance)
{
SystemPropertiesInstance = new SystemProperties();
}
}
return SystemPropertiesInstance;
}
public String getLineSeparator()
{
Object object = ptHashtable.get(LINE_SEPARATOR);
if(null ==object)
{
return null;
}

return object.toString();
}
public String getOSName()
{
Object object = ptHashtable.get(OS_NAME);
if(null ==object)
{
return null;
}

return object.toString();
}
public boolean isWindows()
{
if(getOSName().indexOf("Windows") >= 0)
{
return true;
}

return false;
}
public String getUserDir()
{
Object object = ptHashtable.get(USER_DIR);
if(null ==object)
{
return null;
}

return object.toString();
}
private void InitAllProperties()
{
Properties ps = System.getProperties();
Enumeration EP = ps.propertyNames();
ptHashtable = new HashMap<String, String>();
for(;EP.hasMoreElements();)
{
Stri