dboperations.java

It is an genric employee management application developed using JSP

/*
 * Author :Prakash S
 * Modified :
 *
 */
//Package Declaration 
package com;

//Import Statemenets

import java.sql.Connection;     //Connection Class
import java.sql.DriverManager;  //Driver Class
import java.sql.ResultSet;      //Resultset Class
import java.sql.SQLException;   //Exception Class
import java.sql.Statement;      //Statement Class

public class DBOperations implements AppConstants
{
	/*Declaration Section
	 * ------------------
	 * Connection:    Hodls the Current Connection
	 * driver:        Holds the Current Driver Used
	 * username:      User Name to Connect to the Database
	 * password:      User Password to Connect to the Database
	 * resultset:     It holds the Currently Exectuted Query Results
	 * Source:        Contains the Current Database URL
	 * Statement:     Prepares the Current Statement to Execute  
	 * 
	 * */
	private Connection	connection	= null;

	private String		driver		= "";

	private String		password	= "";

	private ResultSet	resultset	= null;

	private String		source		= "";

	private Statement	statemet	= null;

	private String		username	= "";

	/*Default Constructor 
	 * -----------------
	 * It initialises the Driver,URL,Database to be Used for all Operations
	 * 
	 * */
	public DBOperations()
	{
		setDbParameters();
	}

	/*Deletes a Record from the Database 
	 * Accepts  :a Query String returns
	 * Returns  :No. of Rows Affected 
	 * */
	public int deleteFromTable(String deleteQuery)
	{
		int count = 0;
		try
		{
			System.out.println("Quey:" + deleteQuery);
			//Delete from the Table 
			statemet = connection.createStatement();
			//Return Count of Records Affected
			count = statemet.executeUpdate(deleteQuery);
		} catch (SQLException e)
		{
			System.out.println(e.getLocalizedMessage());
			return count;
		}
		return count;
	}

	/*Closes the  Current Conection with the Database 
	 * Accepts  :Nil
	 * Returns  :Nil 
	 * */
	public void disConnect()
	{
		try
		{
			if (resultset != null)
			{
				resultset.close();//Close the Current ResultSet 
			}
			if (statemet != null)
			{
				statemet.close();//Close the Statement
			}
			if (connection != null)
			{
				connection.close();//Remove Current Database Connection (Disconnect) 
			}
		} catch (SQLException e)
		{
			// TODO Auto-generated catch block
			System.out.println(e.getLocalizedMessage());
		}
	}

	/*Deletes a Record from the Database 
	 * Accepts  :Nil
	 * Returns  :A connnection Object THat Could be used for Subsequent Requests to the database 
	 * */
	public Connection getConnection()
	{

		try
		{
			//initialise the Driver for the database
			Class.forName(driver);
			//Establish Connection to the Database
			connection = DriverManager
					.getConnection(source, username, password);

		} catch (ClassNotFoundException e)
		{
			System.out.println(e.getLocalizedMessage());
		} catch (SQLException e)
		{
			System.out.println(e.getLocalizedMessage());
		}
		return connection;
	}

	/**
	 * @return Returns the driver.
	 */
	public String getDriver()
	{
		return driver;
	}

	/**
	 * @return Returns the password.
	 */
	public String getPassword()
	{
		return password;
	}

	/**
	 * @return Returns the resultset.
	 */
	public ResultSet getResultset()
	{
		if (resultset != null)
		{
			return resultset;
		}
		return null;
	}

	/**
	 * @return Returns the source.
	 */
	public String getSource()
	{
		return source;
	}

	/**
	 * @return Returns the username.
	 */
	public String getUsername()
	{
		return username;

	}

	/*Inserts  a Record To the Database 
	 * Accepts  :a Query String 
	 * Returns  :No. of Rows Affected 
	 * */
	public int insertToTable(String insertQuery)
	{
		int res = 0;
		try
		{
			System.out.println("Quey:" + insertQuery);
			statemet = connection.createStatement();
			//Insert a Record to the Database
			res = statemet.executeUpdate(insertQuery);
			if (res >= 1)
			{
				//Return No of Rows Inserted ( Count)
				return res;
			}
		} catch (SQLException e)
		{
			System.out.println(e.getLocalizedMessage());
		}
		return res;
	}

	public ResultSet selectFromTable(String selectQuery)
	{
		try
		{
			System.out.println("Quey:" + selectQuery);
			statemet = connection.createStatement();
			//get a Result from the Database
			resultset = statemet.executeQuery(selectQuery);
			//Return the Result to the Calling Method
			return resultset;
		} catch (SQLException e)
		{
			System.out.println(e.getLocalizedMessage());
		} finally
		{

		}
		return null;

	}

	/*Initializes the Parameters to Connect to the Databse 
	 * Accepts  :Nil
	 * Returns  :Nil (Sets the Current COnnection to the Database)
	 * */
	public void setDbParameters()
	{
		String user = "";//Current User is Null
		String pass = "";
		setUsername(user);
		setPassword(pass);
		setDriver(DRIVER);
		setSource(SOURCE);
		setUsername(USERNAME);
		setPassword(PASSWORD);

		try
		{
			//Sets the Current COnnection to the Database
			connection = getConnection();
			if (connection != null)
			{
				System.out.println("Successfully Connected to the Database ! :"
						+ connection.toString());
			}
		} catch (Exception e)
		{
			System.out.println(e.getLocalizedMessage());
		}

	}

	/**
	 * @param driver The driver to set.
	 */
	public void setDriver(String driver)
	{
		this.driver = driver;
	}

	/**
	 * @param password The password to set.
	 */
	public void setPassword(String password)
	{
		this.password = password;
	}

	/**
	 * @param source The source to set.
	 */
	public void setSource(String source)
	{
		this.source = source;
	}

	/**
	 * @param username The username to set.
	 */
	public void setUsername(String username)
	{
		this.username = username;
	}

}