3 tier Architecture -JSP Project Module

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How to create a Web Project in Eclipse

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Tasks

• Complete the classes with methods by dividing them into sub-tasks.

Example:

Module- Customer registration

Classes-view, service, DB, Customer bean

Methods-

• saveDetails()-return value Customer id

• fetchDetails(custID) - return Customer details object

• Show the return customer id or error message in a page

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Package

Packages are nothing more than the way we organize filesinto different directories according to their functionality,usability as well as category they should belong to.

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Add a jsp page to WebContent for Registering an Employee

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Creating a bean for passing employee details

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Define required variables

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Generating Getters and Setters

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Creating a Service layer

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• You have to import classes EmployeeBean, DB.AddEmployeesince service layer deals with database layer and bean class.

• Code for service layer is:import com.baabtra.bean.EmployeeBean;import com.baabtra.DB.AddEmployee;

public class AddEmployeeService {public String registerEmployee(EmployeeBean emp){

AddEmployee register= new AddEmployee();String returnmsg=register.registerEmployeeDB(emp);return returnmsg;

}}

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Presentation layer• Post data to page register.jsp• Import required classes to register.jsp<%@ page import="com.Pharma.bean.EmployeeBean"%><%@ page import="com.Pharma.Service.AddEmployeeService"%>

• Store data in variables <%

String employee_id =request.getParameter("employee_id");System.out.println("Employee Id :"+employee_id);String employee_name =request.getParameter("employee_name");String user_name =request.getParameter("user_name");String employee_password =request.getParameter("employee_password");String address =request.getParameter("address");String gender=request.getParameter("gender");String dob =(String)request.getParameter("txt_dob");%>

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• Create object form employee bean and set values for its properties

<%

EmployeeBean emp=new EmployeeBean();

emp.setEmpId(employee_id);

emp.setEmpName(employee_name);

emp.setUserName(user_name);

emp.setPaassword(employee_password);

emp.setAddress(address);

emp.setGender(gender);

emp.setDob(dob1);

emp.setDoj(doj1);

%>

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• Create object for service class and call the method for registering the employee

<%

AddEmployeeService add= new AddEmployeeService();

String result= add.registerEmployee(emp);

%>

• Check the result and do the necessary actionif (result.equals("Success")){.

//Redirect to page for success

response.sendRedirect("Employee.jsp");

}

else{

out.println("Data not saved");

}

%>

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Task-How to connect to DB?

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JDBC

• The JDBC (Java Database Connectivity) API helps a Javaprogram to access a database in a standard way

• JDBC is a specification that specifies two things 1. tells the database vendors how to write a driver program to

interface Java programs with their database2. tells the programmers how to write a Java program to access any

database

• A Driver written according to this standard is called the JDBC Driver

• All related classes and interfaces are present in the java.sql package

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• The steps involved in a database interaction are:

– Loading the specific driver(there are different drivers for different DB)

– Making a connection to the database using the predefined methods in the java.sql package

– Sending and executing SQL statements to the database

– Processing the results

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Step1: Load the database Driver

• Load the driver class by calling Class.forName() with the Driver class name as an argument.

• Once loaded, the Driver class creates an instance of itself in the memory from which it is then used

• The General format is :Class.forName( String ClassName );

• Example :Class.forName ("com.mysql.jdbc.Driver");

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Step2: Setting Connection using Driver Manager class

– Driver Manager Manages all the JDBC Drivers that are loaded in the memory

– Its getConnection() method is used to establish a connection to a database.

– It uses a username, password, and a jdbc url to establish a connection to the database and returns a connection object.

Connection connection =DriverManager.getConnection (url , username, password);

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Connection conn =null;

String username = "root";

String password = "";

String url = "jdbc:mysql://localhost/project";

Class.forName ("com.mysql.jdbc.Driver");

conn = DriverManager.getConnection (url, userName, password);

DB ipaddress Database

name

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Step3:Create a Statement object

• After a connection is obtained we can interact with the database.

• We use methods defined in Connection interface for interacting with the database via the established connection.

• To execute SQL statements, we need to instantiate a Statement object from the connection object by using the createStatement() method.

Statement statement = connection.createStatement();

• A statement object is used to send and execute SQL statements to a database.

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Statement interface• Defines methods that are used to interact with database via the execution

of SQL statements.

• The different methods are:

– executeQuery(String query) - executes an SQL statement (SELECT) that

queries a database and returns a ResultSet object.

– getResultSet() - used to retrieve the ResultSet object

– executeUpdate(String query) - executes an SQL statement (INSERT ,UPDATE

or DELETE) that updates the database and returns an integer value which

specifies the number of rows modified

– execute(String query) - executes an SQL statement that is written as String object

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ResultSet Interface

• Maintains a pointer to a row within the tabular results obtained .

• The next() method is used to iterate through the rows of the tabularresults. Initially the iterator is initialized to a position before the first row.Hence we have to call next() once to move it to the first row.

• The different methods are:

– getBoolean(int) - Get the value of a column in the current row as a Java boolean.

– getDouble(int) - Get the value of a column in the current row as a Java double.

– getInt(int) - Get the value of a column in the current row as a Java int.

– getString(String)-Get value as java string

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Database connection classimport java.sql.DriverManager;

import com.mysql.jdbc.Connection;

public class

{//declare connection as instance variable

public Connection conn;

public Dbconnection()

{ //constructor for the class

String url="jdbc:mysql://localhost:3306/";

String dbname=“database_name";

String driver="com.mysql.jdbc.Driver";

String dbusername="root";

String dbpassword="baabtra";

try {

Class.forName(driver).newInstance();

conn=(DriverManager.getConnection(url+dbname,dbusername,dbpassword);

System.out.println("connected......");

} catch (Exception e) {

System.out.println(e.getMessage());

}}}

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Creating DB layer

• Create a method inside AddEmployee classpublic String registerEmployeeDB(EmployeeBean emp)

{

}

• Strip the object ‘emp’ to get values and store it in variables

String employee_id=emp.getEmpId();

String employee_name=emp.getEmpName();

String user_name=emp.getUserName();

String employee_password=emp.getPaassword();

String address=emp.getAddress();

String gender=emp.getGender();

String dob=emp.getDob();

String doj=emp.getDoj();

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Add try catch block

try{

Connection conn=dbconnection.conn;

Statement st=(Statement) conn.createStatement();

try{

Statement st= (Statement) conn.createStatement();

//your logic here

}

catch (Exception e) {

System.out.println(e);

}

catch (Exception e) {

System.out.println(e);

e.printStackTrace

}

Finally{

conn.close()

} } 38

Do the database operation for registering the employee

//insert data into login tableString sqlQuery ="insert into tbl_login(user_name, password,role)"+

"values('"+user_name+"', '"+employee_password+"','EMPLOY')";

int Count=st.executeUpdate(sqlQuery) ;//Check whether data is inserted or not if (Count>0){

int id=0;//select currently inserted id (auto increment )from login table

ResultSet rs=st.executeQuery("select max(pk_login_id) as id from tbl_login ");while(rs.next()){

id=rs.getInt("id");}

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//Insert data to employee table

sqlQuery="insert into tbl_employe(pk_employee,fk_loginid,emp_first_name,emp_addres, "+

"emp_gender,emp_dob,emp_doj) values('"+employee_id+"',"+ id+",'"+employee_name+"','"+

address+"','"+gender+"','"+dob+"','"+doj+"')";

int Count1=st.executeUpdate(sqlQuery);

//Return success or fail depending on status of database operation

if (Count1>0){

return "Success";

}}

else

{

return "Fail";

}

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Selecting and displaying data from database using list

• Create method for getting data in database layer

public List getEmployeeListDB(){

//code for connecting to database

//declarea list of Employee bean

//do the database operation (select data from database)

//store the result set in the list

//pass it to service layer

}

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//Declare list of employee bean

List<EmployeeBean > details=new ArrayList<EmployeeBean >();

ResultSet rs=s.executeQuery("Select * from employees");

//loop to fetch the query results one by one

while(rs.next()){

//ceating object to save each row details

EmployeeBean emp=new CustomerBean();

emp.setName(rs.getString("name"));

emp.setAddress(rs.getString("address"));

emp.setEmail(rs.getString("email"));

//adding the objects to the list object that was made

details.add(emp);

}

conn.close();

//returning the list with objects

return details;

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Code in service class

import java.util.List;import com.babte.DB.Employee;

public class EmployeeService {public List getEmployeeListService(){

EmployeeDB ObjEmp=new EmployeeDB();List list=ObjEmp. getEmployeeListDB();return list;

}}

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Code in JSP

<%@page import="com.babate.service.EmployeeService"%>

<%@page import="java.util.List"%>

<%@page import="com.babte.Bean.EmployeeBean"%><html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">

<title>Insert title here</title>

</head>

<body>

Employee Details

<table border="1“>

<tr>

<td>Sl No</td>

<td>Name</td>

<td>Address</td>

<td>Email</td>

</tr>

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<%

EmployeeService service=new EmployeeService ();

List details= service. getEmployeeListService();

for(int i=0;i<details.size();i++)

{

EmployeeBean emp =(EmployeeBean )details.get(i);

String name= emp.getName();

String address= emp.getAddress();

String email= emp.getEmail();

%>

<tr>

<td><%=i+1%></td>

<td><%=name%></td>

<td><%=address%></td>

<td><%=email%></td>

</tr>

<%} %>

</table>

</body>

</html>45

End of day

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Thanks in advance.

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