Reading and loading sql queries from properties file

[Ravi Sree]

Hi all,

I am working on a web application project whose access to data is done by using the DAO pattern.
Here I need to load the queries from a properties file placed inside WEB-INF.
Following is the code i used:

PreparedStatementCreatorBean

package net.util;

import java.io.InputStream;
import java.io.IOException;
import java.util.Properties;

import java.sql.Connection;
import java.sql.Date;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Time;
import java.sql.Timestamp;

import net.dao.DAOException;

public class PreparedStatementCreatorBean
{
	private static final long serialVersionUID = -4381510312527568568L;

	private Properties queries;
	private InputStream inputStream;
	
	private static PreparedStatementCreatorBean INSTANCE = new PreparedStatementCreatorBean();
	private static String key = null;
	private String query = null;
	private static Connection _c = null;
	private static Object[] paramValues = null;
	private PreparedStatement _ps;
	
	private PreparedStatementCreatorBean()
	{
		initialize();
	}

	void initialize()
	{
		String propFile = null;
		try
		{
			propFile = "/WEB-INF/classes/queries.properties";
			this.getClass().getClassLoader();
			inputStream = ClassLoader.getSystemResourceAsStream(propFile);		// This where iam getting a NullPointerException
			if(inputStream == null)
			{
				throw new DAOException("cannot read property file!");
			}
			else
			{
				queries = new Properties();
				queries.load(inputStream);
			}
		}
		catch(IOException ioex)
		{
			ioex.printStackTrace();
		}
		catch(Exception ex)
		{
			ex.printStackTrace();
		}
	}
	
	public static PreparedStatementCreatorBean getInstance(Connection _con, String _key, Object..._paramValues)
	{
		_c = _con;
		key = _key;
		paramValues = _paramValues;
		return INSTANCE;
	}
	
	public PreparedStatement createPreparedStatement() throws DAOException
	{		
		try
		{
			query = getQuery(key);
			_ps = _c.prepareStatement(query);
			_ps = prepareStatement(_ps, values);
		}
		catch(SQLException sqlex)
		{
			throw new DAOException(sqlex);
		}
		return _ps;
	}

	private String getQuery(String _key)
	{
		String _query = null;
		if(queries != null)
		{
			if(queries.containsKey(_key))
			{
				_query = queries.getProperty(_key);
			}
		}
		return _query;
	}
	
	private PreparedStatement prepareStatement(PreparedStatement _ps, Object... params) throws DAOException
	{
		try
		{
			for (int i = 0; i < params.length; i++)
			{
				Object arg = params[i];
				if (arg instanceof String)
				{
					_ps.setString(i + 1, (String) arg);
				}
				else if (arg instanceof Integer)
				{
					_ps.setInt(i + 1, (Integer) arg);
				}
				else if (arg instanceof Float)
				{
					_ps.setFloat(i + 1, (Float) arg);
				}
				else if (arg instanceof Long)
				{
					_ps.setLong(i + 1, (Long) arg);
				}
				else if (arg instanceof Double)
				{
					_ps.setDouble(i + 1, (Double) arg);
				}
				else if (arg instanceof Boolean)
				{
					_ps.setBoolean(i + 1, (Boolean) arg);
				}
				else if (arg instanceof Date)
				{
					_ps.setDate(i + 1, (Date) arg);
				}
				else if (arg instanceof Time)
				{
					_ps.setTime(i + 1, (Time) arg);
				}
				else if (arg instanceof Timestamp)
				{
					_ps.setTimestamp(i + 1, (Timestamp) arg);
				}
				else if(arg instanceof Object[])
				{
					_ps.setObject(i + 1, arg);
				}
				/*else
				{
					throw new DAOException("Unsupported parameter type passed as parameter for Prepared statement => '" + arg.getClass().getSimpleName() + "'");
				}*/
			}
		}
		catch(SQLException sqlex)
		{
			throw new DAOException(sqlex.getMessage());
		}
		return _ps;
	}

But It doesnt read the properties file.
I cant make out where iam going wrong.

Thanks in advance,

Sree

[Wouter Oet]

You're not using the class'es ClassLoader but a static method of the class ClassLoader.

[Maneesh Godbole]

Lucky Sree wrote:

Please check your private messages for an important administrative matter.

[Ravi Sree]

Wouter Oet wrote:You're not using the class'es ClassLoader but a static method of the class ClassLoader.

Hi Wouter Oet,

Thanks for replying.

I did the changes as your suggested,
but it is still showing the same error at the same line.

Regards,
Sree