public static void fun1(){

         Properties v = new Properties();

         v.setProperty("a","1");

         v.setProperty("a1","11");

         v.setProperty("a2","111");

         System.out.println(v);

         // 获取键值

         String s = v.getProperty("a");

         // 根据 键 获取 值

         System.out.println(s);

         //将集合中的键  存储到Set集合

         Set<String> set = v.stringPropertyNames();

         for(String k:set){

             //System.out.println(k);

             String value = v.getProperty(k);

             System.out.println(k+":"+value);

         }

     }