import java.io.BufferedReader;

 import java.io.IOException;

 import java.io.InputStream;

 import java.io.InputStreamReader;

 import java.util.Properties;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 /**

  * 配置文件读取工具

  */

 public class ConfigurableConstants

 {

     protected static final String PROPERTIES_PATH = "config.properties";

     protected static Log logger = LogFactory.getLog(ConfigurableConstants.class);

     protected static Properties p = new Properties();

     static

     {

         init(PROPERTIES_PATH);

     }

     /**

      * 静态读入属性文件到Properties p变量中

      */

     protected static void init(String propertyFileName)

     {

         InputStream in =  null;

         try

         {

             // class.getClassLoader()获得该class文件加载的web应用的目录，如WEB-INF/classes/就是根目录

             // getResourceAsStream(relativeFilePath):定位该文件且获得它的输出流

             in = ConfigurableConstants.class.getClassLoader().getResourceAsStream(propertyFileName);

             BufferedReader bf = null;

             if (in != null)

                 // load输出流到Properties对象中

                 // 因为字节流是无法读取中文的，所以采取reader把inputStream转换成reader用字符流来读取中文。

                 bf = new BufferedReader(new InputStreamReader(in));

             p.load(bf);

         }

         catch (IOException e)

         {

             logger.error("load " + propertyFileName + " into Constants error!");

         }

         finally

         {

             if (in != null)

             {

                 try

                 {

                     in.close();

                 }

                 catch (IOException e)

                 {

                     logger.error("close " + propertyFileName + " error!");

                 }

             }

         }

     }

     /**

      * 封装了Properties类的getProperty函数,使p变量对子类透明.

      *

      * @param key

      *            property key.

      * @param defaultValue

      *            当使用property key在properties中取不到值时的默认值.

      */

     public static String getProperty(String key, String defaultValue)

     {

         return p.getProperty(key, defaultValue).trim();

     }

 }