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Business Delegate Design Pattern

index.jsp 
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">

<title>Index Page</title>
</head>
<body>

<a href="/javaT/registerStudent.jsp">Show Student Registration Information</a>

</body>
</html>
registerStudent.jsp 
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Register Student</title>
</head>
<body>

<form action="register">
<table>
<tr><td>Student Id : </td><td> <input type="text" name="studentId"></td></tr>
<tr><td> Name : </td><td> <input type="text" name="name"></td></tr>
<tr><td>Course Id : </td><td> <input type="text" name="courseId"></td></tr>
<tr><td colspan="2"> <input type="submit" value="Register"></td></tr>
</table>
</form>

</body>
</html>
error.jsp 
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Error !!!</title>
</head>
<body>

<p style="color:red;">
  Error while processing your request. Please contact administration.
</p>

</body>
</html>
confirm.jsp 
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Registration Successfully</title>
</head>
<body>

<p style="color:green;">
  Student ${studentId} register successfully ....
</p>

</body>
</html>

package business.delegate;

import java.io.Serializable;

public class StudentBO implements Serializable {
	
	private int id;
	private String name;
	
	//getters and setters
	
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
}

package business.delegate;

import java.io.Serializable;

public class StudentCourseBO implements Serializable {

	private int studentId;
	private int courseId;
	
	// setters and getters
	
	public int getStudentId() {
		return studentId;
	}
	public void setStudentId(int studentId) {
		this.studentId = studentId;
	}
	public int getCourseId() {
		return courseId;
	}
	public void setCourseId(int courseId) {
		this.courseId = courseId;
	}	
}
db.properties 
db.driverClassName = oracle.jdbc.driver.OracleDriver
db.url = jdbc:oracle:thin:@localhost:1521:xe
db.userName = system
db.password = tiger

package business.delegate;

import java.sql.Connection;
import java.sql.SQLException;

public interface StudentDao {
 void insert(StudentBO studentBO, Connection con) throws SQLException;
}

package business.delegate;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.logging.Logger;

public class StudentDaoImpl implements StudentDao {
	
  //SQL queries
 private final String INSERT_QUERY="insert into student(student_id,name) values(?,?)";
 private static Logger logger;
 
static {
  logger=Logger.getLogger("log_file");
}

@Override
public void insert(StudentBO studentBO, Connection con) throws SQLException {

 PreparedStatement pstmt=null;

 try{
  pstmt=con.prepareStatement(INSERT_QUERY);
  pstmt.setInt(1, studentBO.getId());
  pstmt.setString(2, studentBO.getName());
  pstmt.executeUpdate();
 }catch(SQLException e){
	 logger.throwing("StudentDao", "Unable to perform insert", e);
	 throw e;
 }finally{	 
     if(pstmt != null)
      pstmt.close();  
 }
 
}
}


/*
  create table student(student_id number(20),name varchar2(15)); 
 */

package business.delegate;

import java.sql.Connection;
import java.sql.SQLException;

public interface StudentCourseDao {
	 void insert(StudentCourseBO studentCourseBO, Connection con) throws SQLException;
}

package business.delegate;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.logging.Logger;

public class StudentCourseDaoImpl implements StudentCourseDao {
	
  //SQL queries
 private final String INSERT_QUERY="insert into course(student_id, course_id) values(?,?)";
 private static Logger logger;
 
static {
  logger=Logger.getLogger("log_file");
}

@Override
public void insert(StudentCourseBO studentCourseBO, Connection con) throws SQLException {

 PreparedStatement pstmt=null;

 try{
  pstmt=con.prepareStatement(INSERT_QUERY);
  pstmt.setInt(1, studentCourseBO.getStudentId());
  pstmt.setInt(2, studentCourseBO.getCourseId());
  pstmt.executeUpdate();
 }catch(SQLException e){
	 logger.throwing("StudentCourseDao", "Unable to perform insert", e);
	 throw e;
 }finally{	 
     if(pstmt != null)
      pstmt.close();  
 }
 
}
}


/*
  create table course(student_id number(20), course_id number(20)); 
 */

package business.delegate;

import java.sql.SQLException;

public interface RegistrationDelegate {
   void register(RegistrationVO registrationVO) throws SQLException, ClassNotFoundException, GenericException;
}

package business.delegate;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.logging.Logger;

public class RegistrationDelegateImpl implements RegistrationDelegate {
	
private static Logger logger;

static{
  logger=Logger.getLogger("log_file");
}

@Override
public void register(RegistrationVO registrationVO) throws SQLException, ClassNotFoundException, GenericException {
 boolean isEx=false;
 Connection con=null;
 StudentBO studentBO=null;
 StudentCourseBO studentCourseBO=null;
 StudentDao studentDao=null;
 StudentCourseDao studentCourseDao=null;
 
 try{
  con=ConnectionFactory.getConnection();
  
  studentBO=new StudentBO();
  studentBO.setId(Integer.parseInt(registrationVO.getStudentId()));
  studentBO.setName(registrationVO.getName());
  
  studentDao=new StudentDaoImpl();
  studentDao.insert(studentBO, con);
  
  studentCourseBO=new StudentCourseBO();
  studentCourseBO.setStudentId(Integer.parseInt(registrationVO.getStudentId()));
  studentCourseBO.setCourseId(Integer.parseInt(registrationVO.getCourseId()));
    
  studentCourseDao=new StudentCourseDaoImpl();
  studentCourseDao.insert(studentCourseBO, con);
  
 }catch(SQLException e){
   logger.throwing("RegistrationDelegateImpl", "Unable to register student", e);
   throw new GenericException(e);
 }catch (ClassNotFoundException e) {
   logger.throwing("RegistrationDelegateImpl", "Unable to register student", e);
   throw new GenericException(e);
 }finally{
	 if(con != null) {
		try{
			if(isEx)
				 con.rollback();
			 else 
				 con.commit();
			con.close();
		}catch(SQLException e){
			logger.throwing("RegistrationDelegateImpl", "Unable to commit/rollback/clode connection", e);
			throw new GenericException(e);
		}
		
	 }//if
		
 }//finally
 
 
}

}

package business.delegate;

import java.io.IOException;
import java.sql.SQLException;
import java.util.logging.Logger;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class RegistrationServlet extends HttpServlet {
  private static Logger logger=Logger.getLogger("log_file");
  
@Override
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

  boolean isEx=false;
  String studentId=null;
  String name=null;
  String courseId=null;
  String page=null;
  RegistrationVO registrationVO=null;
  RegistrationDelegate registrationDelegate=null;
  RequestDispatcher requestDispatcher=null;
  
  studentId=request.getParameter("studentId");
  name=request.getParameter("name");
  courseId=request.getParameter("courseId");
  
  registrationVO=new RegistrationVO();
  registrationVO.setStudentId(studentId);
  registrationVO.setName(name);
  registrationVO.setCourseId(courseId);
  
  registrationDelegate=new RegistrationDelegateImpl();  
 
  try{
	 registrationDelegate.register(registrationVO);
	 request.setAttribute("studentId", studentId);
  }catch(GenericException | ClassNotFoundException | SQLException e){
	  isEx=true;
	  logger.throwing("Registration Servlet", "Error occured during registration", e);
  }
  
  if(isEx)
	  page="error.jsp";
  else
	  page="confirm.jsp";
  
  requestDispatcher=request.getRequestDispatcher(page);
  requestDispatcher.forward(request, response);  
  
}

}

package business.delegate;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
import java.util.ResourceBundle;
import java.util.Set;
import java.util.logging.Logger;

public class ConnectionFactory {
 private static Properties props;
 private static Logger logger;
 
static{
 logger=Logger.getLogger("log_file");
 props=new Properties();
 ResourceBundle rb=ResourceBundle.getBundle("business/delegate/db"); // business.delegate.db
 Set<String> keys=rb.keySet();
 for(String key:keys){
	 props.put(key, rb.getString(key));
 } 
}

public static Connection getConnection() throws SQLException, ClassNotFoundException {
 Connection con=null;
 
 try{
	Class.forName(props.getProperty("db.driverClassName"));
    con=DriverManager.getConnection(props.getProperty("db.url"),props.getProperty("db.userName"),props.getProperty("db.password"));
    con.setAutoCommit(false);
 }catch(SQLException e){
   logger.throwing("ConnectionFactory", "Unable to get Connection", e);
  throw e ;
 }catch (Exception e) {
   logger.throwing("ConnectionFactory", "Unable to load driver class", e);
   throw e ;
} 
 return con;
 
}
 
}

package business.delegate;

public class GenericException extends Throwable {

public GenericException(){
	super();
}

public GenericException(String str, Throwable exp){
	super(str,exp);
}

public GenericException(String str){
	super(str);
}

public GenericException(Throwable exp){
	super(exp);
}

}

package business.delegate;

import java.io.Serializable;

public class RegistrationVO implements Serializable{

	private String studentId;
	private String name;
	private String courseId;
	
	// setters and getters
	
	public String getStudentId() {
		return studentId;
	}
	public void setStudentId(String studentId) {
		this.studentId = studentId;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getCourseId() {
		return courseId;
	}
	public void setCourseId(String courseId) {
		this.courseId = courseId;
	}

}
web.xml 
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"   
xmlns="http://java.sun.com/xml/ns/javaee"   
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee   
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"   
id="WebApp_ID" version="3.0">  

<display-name>BusinessDelegate</display-name>
<servlet>
 <servlet-name>delegate</servlet-name>
 <servlet-class>business.delegate.RegistrationServlet</servlet-class>
</servlet>
<servlet-mapping>
 <servlet-name>delegate</servlet-name>
 <url-pattern>/register</url-pattern>
</servlet-mapping>

<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
 
</web-app>
output : 
http://localhost:8001/javaT/ 
(OR)
http://localhost:8001/javaT/register?studentId=123&name=ashok&courseId=432

Student 123 register successfully ....

//add required jar files to project lib flder like servlet-api.jar, ojdbc14.jar etc.,


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