public class getProperties {
 private static Properties config = null;

 static {
  InputStream in = getProperties.class.getClassLoader().getResourceAsStream(
    "config.properties");
  config = new Properties();
  try {
   config.load(in);
   in.close();
  } catch (IOException e) {
   System.out.println("No AreaPhone.properties defined error");
  }
 }

 // 根据key读取value
 public static String readValue(String key) {
  // Properties props = new Properties();
  try {
   String value = config.getProperty(key);
   return value;
  } catch (Exception e) {
   e.printStackTrace();
   System.err.println("ConfigInfoError" + e.toString());
   return null;
  }
 }

 // 读取properties的全部信息
 public static void readAllProperties() {
  try {

   Enumeration en = config.propertyNames();
   while (en.hasMoreElements()) {
    String key = (String) en.nextElement();
    String Property = config.getProperty(key);
    System.out.println(key + Property);
   }
  } catch (Exception e) {
   e.printStackTrace();
   System.err.println("ConfigInfoError" + e.toString());
  }
 }

 public static void main(String args[]) {
  // String LaSaPhone=config.getProperty("LaSaPhone");
  // System.out.println(LaSaPhone);
  // System.out.println(getPhone.readValue("LaSaPhone"));
  getProperties.readAllProperties();
 }
}

config.properties文件：
#area message phone :
LaSaPhone=08916539292
RikaZePhone=08916539292
ShanNanPhone=08916539292
LiZhiPhone=08916539292
ALiPhone=08916539292
ChangDuPhone=08916539292
NaQuPhone=08916539292

我将config.properties文件放在根目录下，但运行时报：
java.lang.ExceptionInInitializerError
Caused by: 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 com.liuchen.getProperties.<clinit>(getProperties.java:16)
Exception in thread "main" 
似乎config.load(in);这里的in是null，但有文件啊，这是怎么回事？谢谢！