wrapper.java

一个关于商业的网站

/**
 * $file: Paser.java $
 * $Revision: 1.0 $
 * $ Modified Record:
 * $2003.4.6: Created.
 * Copyright (C) 2003 www.studyjava.com All rights reserved.
 */
 
package com.everstar.util;
import java.io.*;
import java.util.*;


/**
 *  this class read properties from a defined properties file like ../path/webstar.properties
 *  all the needed output information strings including error string and waring or information   
 *  are stored in this properties file. thus client side programmers only need redirect to Error.jsp
 *  with a URL parameter "message", which should be in the form of predefined MACRO like "NEWS_ERROR_NOFILE" 
 *  Error.jsp will get the reference of a instance of class Paser and invoke a method with parameter " message"  
 *  whenever we need to update the information strings, what we need to do is merely update the properties file 
 */


public class Wrapper
{
     /**
     * stores the necessary properties load from the properties file
     */

     private Properties information;
 
     /**
     * string for the final output
     */
     private String msgOutput=null;
     /**
      *propsName defines the name of properties file used here
      */
     private static String resourceURI = "/jive.properties";    
     
     
     private final String defaultName="SYSTEM_DEFAULT";
     //private PropertyManager manager=null;
     private String defaultValue;
    /**
     * The Constructor method will be called only once since there will be only
     * one instance of this class within the whole application;thus the timeconsuming
     * work of loading all properties and their values from properties file is run here
     * later,each time .jsp file calls Error.jsp will get proper output string from the 
     * same properties instance "information" through calling Wrapper.output(String msgInput)
     * a instance of PropertyManager was created too to load properties from property file
     * cause we dont want to interfere with the loading detail in Wrapper
     */
    
    
     public  Wrapper()
       {
         
         information=new Properties();
         loadProp();

         //Enumeration propNames=manager.propNames();
         //   while(propNames.hasMoreElements())
         //     { String propName=propNames.nextElement();
         //     	String propValue=manager.getProp(propName);
         //     	information.put(propName,propValue);
              	 
        }  
   
   
     /**
     * Error.jsp will call this method to print out proper message
     
     
     *@param in  message passed in from Error.jsp
     *@return the proper output string get from properties file
     */
      
     public String output(String in) 
       {
         //first try to get according value from properties "information"
         
                
         msgOutput=getProperties(in);
         if(msgOutput!=null)          
            {
             return msgOutput;
            }
          return getDefault(in);   
        } 
     
     
     private String getProperties(String in )
       {
        return (String)information.get(in);
       }
      
     private String getDefault(String in)
       {
        // here I want to parse the input string first to judge its module name and then try to get module's default output string
        String defaultPropName=getModuleName(in)+"_DEFAULT";
       
       
          if (( defaultValue=getProperties(defaultPropName))!=null)
    
             return defaultValue;
          //if the default exception information has not been found, we just take it as a system level exception       
          
            if (getProperties(defaultName)==null)	
              // both module default and system default exception cant be found(properties file was not properly defined)
               return "there is no exception information defined yet ";
            return getProperties(defaultName);
            	
        //return  (String)prop.get(DEFULT);    
       }
     
     private void loadProp()
       {
        InputStream in = null;
        try 
          {
            in = getClass().getResourceAsStream(resourceURI);
            information.load(in);
          }
        catch (Exception e) 
          {
            System.err.println("Error reading Jive properties in PropertyManager.loadProps() " + e);
            e.printStackTrace();
          }
        finally
          {
            try 
              {
                in.close();
              } 
            catch (Exception e) { }
          }
     }	
     private String getModuleName(String in)
       {
       	if(in!=null)
       	  {
       	   String f=in.substring(0,in.indexOf('_'));
                    
           return f;
          } 	
         
         // if there is no such module name in the property file, we just take it as system level exception
       	 return getModuleName(defaultName);   
       	}
       	
     
}