tablibconfig.java

这是一个mvc模式

package jsp.tags.dapact.conf;

import java.io.*;
import java.util.*;
/**
 * Title:        Data Aware Processing And Control Tags
 * Description:  Tag library for the processing and controlling the input and output of data.
 * Copyright:    LGPL (http://www.gnu.org/copyleft/lesser.html)
 * Compile Date: @compile_date@
 * @author Allen M Servedio
 * @amp_sign@version @VERSION@
 */

/**
 * Class implements reading and processing of configuration file for system.
 */
public class TablibConfig
{
  /**
   * Interface that defines property files that this class uses.
   */
  public interface PropertyFiles
  {
    /**
     * Defines the properties for the fully qualified class names.
     */
    public static final String FULLY_QUALIFIED_CLASS_PROPS = "FullyQualifiedClass.properties";
  }

  /**
   * Default constructor.
   */
  private TablibConfig()
  {
  }

  /**
   * Returns a property list of name-value pairs listing fully qualified class names
   * (value) that can be looked up by a name.
   *
   * @return properties listing the name-value pairs for this property file.
   *
   * @exception IOException thrown when there is a problem reading the property file.
   */
  public static Properties getFullyQualifiedClassTable() throws IOException
  {
    if (propFullyQualifiedClassTable == null)
    {
      throw new IOException(propFullyQualifiedClassTableMsg);
    }
    return propFullyQualifiedClassTable;
  }

  /**
   * This will hold any error messages created while trying to load the fully
   * qualified class table.
   */
  private static String propFullyQualifiedClassTableMsg;
  /**
   * Try to initialize the fully qualified class table in a thread safe way (ie. while
   * the class is being loaded).
   */
  private static Properties propFullyQualifiedClassTable;
  static
  {
    try
    {
      InputStream in = Class.forName("jsp.tags.dapact.conf.TablibConfig").getResourceAsStream(PropertyFiles.FULLY_QUALIFIED_CLASS_PROPS);
      if (in != null)
      {
        try
        {
          try
          {
            propFullyQualifiedClassTable = new Properties();
            propFullyQualifiedClassTable.load(in);
          }
          finally
          {
            in.close();
          }
        }
        catch (IOException e)
        {
          propFullyQualifiedClassTable = null;
          // If it could not create the property table, create a message saying so.
          propFullyQualifiedClassTableMsg = "Unable to load the following properties file from the directory containing the jsp.tags.dapact.conf.TablibConfig class:"
            + PropertyFiles.FULLY_QUALIFIED_CLASS_PROPS + " because " + e.toString();
          UserClassFactory.getLogger().log("The following exception occurred while trying to load the fully qualified class table.", e);
        }
      }
    }
    catch (ClassNotFoundException e)
    {
      propFullyQualifiedClassTableMsg = "Unable to find class jsp.tags.dapact.conf.TablibConfig in class path.";
    }
  }

  /**
   * For testing...
   */
  public static void main(String[] args)
  {
    try
    {
      Properties prop = getFullyQualifiedClassTable();
      Enumeration names = prop.propertyNames();
      if (names != null)
      {
        while (names.hasMoreElements())
        {
          String name = (String)names.nextElement();
          System.out.println(name + " = " + prop.getProperty(name));
        }
      }
    }
    catch (Exception e)
    {
      e.printStackTrace();
    }
  }
}