单例模式

private static SpotDfContantner instance = null; 

public static SpotDfContantner getInstance() {
  if (instance == null) {
   synchronized (SpotDfContantner.class) {
    if (instance == null) {
     instance = new SpotDfContantner();
    }
   }
  }
  return instance;
 }

使用：SpotDfContantner.getInstance()