Wednesday, 21 August 2013

Data Access Object Design Pattern or DAO Pattern


Data Access Object Design Pattern - Introduction



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Data Access Object Design Pattern - Class and Sequence Diagram



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Data Access Object Design Pattern - Implementation


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DAO Class Diagram


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DAO Design Pattern Sample Code

Employee.java

public class Employee
{
private int    employeeId;
private String name;
private int    age;

public int getEmployeeId()
{
return employeeId;
}

public void setEmployeeId( int employeeId )
{
this.employeeId = employeeId;
}

public String getName()
{
return name;
}

public void setName( String name )
{
this.name = name;
}

public int getAge()
{
return age;
}

public void setAge( int age )
{
this.age = age;
}

}

EmployeeDao.java

import java.util.List;

public interface EmployeeDao
{
public List<Employee> getAllEmployees();

public void addEmployee( Employee employee );

public Employee getEmployee( int employeeId );

public void updateEmployee( Employee employee );

public void deleteEmployee( int employeeId );

}


EmployeeDaoImpl.java

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

public class EmployeeDaoImpl implements EmployeeDao
{
@Override
public List<Employee> getAllEmployees()
{
DataSource dataSource = new DataSource();
Connection con = dataSource.createConnection();
Statement stmt = null;
ResultSet rs = null;
List<Employee> employeeList = new ArrayList<Employee>();
try
{
String query = "SELECT * FROM employee";
stmt = con.createStatement();
rs = stmt.executeQuery(query);
while( rs.next() )
{
Employee employee = new Employee();
employee.setEmployeeId(rs.getInt("Employee_Id"));
employee.setName(rs.getString("Name"));
employee.setAge(rs.getInt("age"));
employeeList.add(employee);
}
}
catch( SQLException e )
{
e.printStackTrace();
}

finally
{
try
{
if( con != null )
{
con.close();
}
if( stmt != null )
{
stmt.close();
}
if( rs != null )
{
rs.close();
}
}
catch( Exception exe )
{
exe.printStackTrace();
}

}
return employeeList;
}

@Override
public void addEmployee( Employee employee )
{
Connection dbConnection = null;
Statement statement = null;

String sql = "insert into employee values(" + employee.getEmployeeId() + ","             + "'" + employee.getName()
               + "'" + "," + employee.getAge() + ")";

try
{
DataSource dataSource = new DataSource();
dbConnection = dataSource.createConnection();
statement = dbConnection.prepareStatement(sql);
statement.executeUpdate(sql);

System.out.println("Record is inserted into Employee table for  Employee : " + employee.getName());

}
catch( SQLException e )
{

e.printStackTrace();

}
finally
{

if( statement != null )
{
try
{
statement.close();
}
catch( SQLException e )
{
e.printStackTrace();
}
}

if( dbConnection != null )
{
try
{
dbConnection.close();
}
catch( SQLException e )
{
e.printStackTrace();
}
}

}

}

@Override
public Employee getEmployee( int employeeId )
{
DataSource dataSource = new DataSource();
Connection con = dataSource.createConnection();
Statement stmt = null;
ResultSet rs = null;
try
{
String query = "SELECT * FROM employee where employee_id="+employeeId;
stmt = con.createStatement();
rs = stmt.executeQuery(query);
while( rs.next() )
{
Employee employee = new Employee();
employee.setEmployeeId(rs.getInt("Employee_Id"));
employee.setName(rs.getString("Name"));
employee.setAge(rs.getInt("age"));
return employee;
}
}
catch( SQLException e )
{
e.printStackTrace();
}

finally
{
try
{
if( con != null )
{
con.close();
}
if( stmt != null )
{
stmt.close();
}
if( rs != null )
{
rs.close();
}
}
catch( Exception exe )
{
exe.printStackTrace();
}

}
return null;
}

@Override
public void updateEmployee( Employee employee )
{
Connection dbConnection = null;
Statement statement = null;

String sql = "update employee set name=" + "'" + employee.getName() + "'" + "where employee_id="
               + employee.getEmployeeId();

try
{
DataSource dataSource = new DataSource();
dbConnection = dataSource.createConnection();
statement = dbConnection.prepareStatement(sql);
statement.executeUpdate(sql);

System.out.println("Record is updated into Employee table for Employee id : "
               + employee.getEmployeeId());

}
catch( SQLException e )
{

e.printStackTrace();

}
finally
{

if( statement != null )
{
try
{
statement.close();
}
catch( SQLException e )
{
e.printStackTrace();
}
}

if( dbConnection != null )
{
try
{
dbConnection.close();
}
catch( SQLException e )
{
e.printStackTrace();
}
}

}
}

@Override
public void deleteEmployee( int  employeeId )
{
Connection dbConnection = null;
Statement statement = null;

String sql = "delete from employee where employee_Id="+ employeeId;

try
{
DataSource dataSource = new DataSource();
dbConnection = dataSource.createConnection();
statement = dbConnection.prepareStatement(sql);
statement.executeUpdate(sql);

System.out.println("Record is deleted from Employee table for Employee id : "
               + employeeId);

}
catch( SQLException e )
{

e.printStackTrace();

}
finally
{

if( statement != null )
{
try
{
statement.close();
}
catch( SQLException e )
{
e.printStackTrace();
}
}

if( dbConnection != null )
{
try
{
dbConnection.close();
}
catch( SQLException e )
{
e.printStackTrace();
}
}

}
}

}


DataSource.java

import java.sql.Connection;

import org.apache.commons.dbcp.BasicDataSource;

public class DataSource
{
Connection      connection = null;
BasicDataSource bdSource   = new BasicDataSource();

public DataSource()
{
bdSource.setDriverClassName("com.mysql.jdbc.Driver");
bdSource.setUrl("jdbc:mysql://localhost:3306/RamJ2EE");
bdSource.setUsername("root");
bdSource.setPassword("root");
}

public Connection createConnection()
{
Connection con = null;
try
{
if( connection != null )
{
System.out.println("Cant create a New Connection");
}
else
{
con = bdSource.getConnection();
}
}
catch( Exception e )
{
System.out.println("Error Occured " + e.toString());
}
return con;
}
}

EmployeeDaoPatternDemo.java

public class EmployeeDaoPatternDemo
{

public static void main( String[] args )
{
EmployeeDao employeeDao = new EmployeeDaoImpl();

// Add new Employees
Employee employeeDavid = new Employee();
employeeDavid.setEmployeeId(1);
employeeDavid.setName("David");
employeeDavid.setAge(23);
employeeDao.addEmployee(employeeDavid);
Employee employeeJohn= new Employee();
employeeJohn.setEmployeeId(2);
employeeJohn.setName("John");
employeeJohn.setAge(34);
employeeDao.addEmployee(employeeJohn);
System.out.println();
System.out.println("-------------------------Print all the Employees-------------------------------- Start");
// print all Employees
for( Employee employee : employeeDao.getAllEmployees() )
{
System.out.println("employee: [Employee Id : " + employee.getEmployeeId() + ", Name : "
               + employee.getName() + ",age :" + employee.getAge()+" ]");
}
System.out.println("-------------------------Print all the Employees-------------------------------- End");
System.out.println();

System.out.println("-------------------------Get one Employee based in employee Id =1 ----------- Start");
Employee employee= employeeDao.getEmployee(1);
System.out.println("employee: [Employee Id : " + employee.getEmployeeId() + ", Name : "
               + employee.getName() + ",age :" + employee.getAge()+" ]");
System.out.println("-------------------------Get one Employee based in employee Id =1 ----------- End");
System.out.println();
System.out.println("-------------------------update the employee whose employee Id =1 ----------- Start");
Employee employeeRohan= new Employee();
employeeRohan.setEmployeeId(1);
employeeRohan.setName("Rohan");
employeeDao.updateEmployee(employeeRohan);
System.out.println("-------------------------update the employee whose employee Id =1 ----------- End");
System.out.println();
System.out.println("-------------------------Delete the employee whose employee Id =2 ----------- Start");
employeeDao.deleteEmployee(2);

System.out.println("-------------------------Delte the employee whose employee Id =2 ----------- End");
}

}

Output

Record is inserted into Employee table for Employee : David
Record is inserted into Employee table for Employee : John

-------------------------Print all the Employees-------------------------------- Start
employee: [Employee Id : 1, Name : David,age :23 ]
employee: [Employee Id : 2, Name : John,age :34 ]
-------------------------Print all the Employees-------------------------------- End

-------------------------Get one Employee based in employee Id =1 ----------- Start
employee: [Employee Id : 1, Name : David,age :23 ]
-------------------------Get one Employee based in employee Id =1 ----------- End

-------------------------update the employee whose employee Id =1 ----------- Start
Record is updated into Employee table for Employee id : 1
-------------------------update the employee whose employee Id =1 ----------- End

-------------------------Delete the employee whose employee Id =2 ----------- Start
Record is deleted from Employee table for Employee id : 2
-------------------------Delte the employee whose employee Id =2 ----------- End



DB Script

/*!40101 SET NAMES utf8 */;

/*!40101 SET SQL_MODE=''*/;

/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;

CREATE DATABASE /*!32312 IF NOT EXISTS*/`RamJ2EE` /*!40100 DEFAULT CHARACTER SET latin1 */;

USE `RamJ2EE`;

/*Table structure for table `Employee` */

DROP TABLE IF EXISTS `Employee`;

CREATE TABLE `Employee` (
  `Employee_Id` int(32) NOT NULL,
  `Name` varchar(32) default NULL,
  `Age` int(32) default NULL,
  PRIMARY KEY  (`Employee_Id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;
/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;

JAR files Required

commons-dbcp-1.4.jar
commons-pool-1.6.jar
mysql-connector-java-5.1.21.jar

You can download from : http://mvnrepository.com/

Project Structure

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1 comment:

  1. It would better if u would provide the source code as .java file, and allow them to download.

    ReplyDelete

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