关于读取properties文件的问题，急

public class BusinessFactory {
  protected Logger logger = Logger.getLogger(BusinessFactory.class);
  private static Properties properties = new Properties();
  public BusinessFactory() {
  }  private static void loadProperties(Class className) {
   
    try {
      //new a properties from the inputstream
      InputStream in = className.getResourceAsStream("business.properties");
      properties.load(in);
    }
    catch (FileNotFoundException ex) {
      /** @todo Handle this exception */
   
    }
    catch (IOException ex) {
      /** @todo Handle this exception */
    
    }  }
错误提示java.lang.NullPointerException
at java.io.Reader.<init>(Reader.java:61)
at java.io.InputStreamReader.<init>(InputStreamReader.java:80)
at java.util.Properties.load(Properties.java:189)
at wzsw.device.BusinessFactory.loadProperties(BusinessFactory.java:36)
at wzsw.device.BusinessFactory.create(BusinessFactory.java:58)
at wzsw.device.TestBusinessFactory.testGet(TestBusinessFactory.java:33)
我的properties文件也在当前目录。