java 打印所有环境变量

1. 
   

import java.util.*;
import java.util.Map.*;

public final class tmp
{

        public static void main(String args[])
        {
                Map<String, String> map;

                map = System.getenv();

                Set<Entry<String, String>> sm = map.entrySet();
                Iterator<Entry<String, String>> t = sm.iterator();
                while (t.hasNext())
                {
                        Entry entry = t.next();
                        System.out.println("key: " + entry.getKey() + " " +
                        "value: " + entry.getValue());
                }
        }
}