Pass Value bean/java to servlet

StackOverflow https://stackoverflow.com/questions/22877860

Question

Here i come with a problem to pass value to servlet normally i have to get and set value in Bean class so it have to pass to Dbconnection class and servlet but i could't call bean/dbconnect method in servlet to insert value in databases.can some one guide to go right way to get pass in jsp

Bean-->dbconnect---servlet---register.jsp

welcome.jsp:

<body>
<%  
Bean bean=(Bean)request.getAttribute("bean");  
out.print("Welcome, "+bean.getUsername());  
%>
<p>You are successfully logged in!</p>  
</body>

Index.jsp:

<form action="Controller" method="post">
    User name:<input type="text" name="username">
    Password:<input type="password" name="password">
    <input type="submit" name="Login"> <a href="Register.jsp">Register</a>
</form>

Register.jsp

<form action="Controller" method="post">
User name:<input type="text" name="name" >
Password:<input type="password" name="pass">
Email-id<input type="text" name="emailid">
phone number:<input type="text" name="phone">
<input type="submit" value="submit"><a href="index.jsp">Login</a>
</form>

Bean.java

package Databases;

public class Bean
{

    private   String username;
    private   String password;
    private   String emailid;
    private   String phone;
   /**
     * @return the username
     */
    public String getUsername()
    {
        return username;
    }
    /**
     * @param username the username to set
     */
    public void setUsername(String username)
    {
        this.username = username;
    }
    /**
     * @return the password
     */
    public String getPassword()
    {
        return password;
    }
    /**
     * @param password the password to set
     */
    public void setPassword(String password)
    {
        this.password = password;
    }
    /**
     * @return the emailid
     */
    public String getEmailid()
    {
        return emailid;
    }
    /**
     * @param emailid the emailid to set
     */
    public void setEmailid(String emailid)
    {
        this.emailid = emailid;
    }
    /**
     * @return the phone
     */
    public String getPhone()
    {
        return phone;
    }
    /**
     * @param phone the phone to set
     */
    public void setPhone(String phone)
    {
        this.phone = phone;
    }

}

Dbconnect.java

package Databases;

import java.io.*;
import java.sql.*;
import java.util.ArrayList;
import java.util.Iterator;

public class Dbconnect
{
    public static void main(String args[]) throws ClassNotFoundException
    {
        Dbconnect db = new Dbconnect();
        db.dbconnect();
    }

    public Connection dbconnect() throws ClassNotFoundException
    {

        try
        {
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/mine", "root", "android");

        } catch (SQLException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;

    }

    public String user(Bean bean)
    {
        Connection con = null;
        PreparedStatement prep = null;
        try
        {
            con = dbconnect();
            String sql = "SELECT * user WHERE name = ? AND password = ?";
            prep = con.prepareStatement(sql);

            prep.setString(1, bean.getUsername());
            prep.setString(2, bean.getPassword());

        } 
        catch (Exception e)
        {
            System.out.println("cannot connect");
            e.printStackTrace();
        }
        return "user login";
    }

    public String insertDetail(Bean bean) throws SQLException
    {

        String sql = "insert into user(name,password,email,phone) values(?,?,?,?)";
        Connection con = null;
        PreparedStatement prep = null;

        try
        {
            con = dbconnect();
            prep = con.prepareStatement(sql);

        } catch (ClassNotFoundException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        prep.setString(1, bean.getUsername());
        prep.setString(2, bean.getPassword());
        prep.setString(3, bean.getEmailid());
        prep.setString(4, bean.getPhone());
        prep.executeUpdate();
        prep.close();

        return "successfully added";

    }
}

Controller.java

    package servlet;

import java.io.IOException;
import java.io.PrintWriter;

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

import com.mysql.jdbc.PreparedStatement;

import Databases.Dbconnect;

import Databases.*;

/**
 * Servlet implementation class Loginservlet
 */
public class Controller extends HttpServlet
{
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException
    {

    }

    protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException
    {

        response.setContentType("text/html");
        //PrintWriter out = response.getWriter();

        String name = request.getParameter("name");
        String pass = request.getParameter("pass");
        String email = request.getParameter("emailid");
        String pn = request.getParameter("phone");
        System.out.println("Name :" + name);
        System.out.println("pass :" + pass);
        System.out.println("emailid :" + email);
        System.out.println("phone:" + pn);


        Bean bean=new Bean();  
        bean.setUsername(name);  
        bean.setPassword(pass);  
        bean.setEmailid(email);
        bean.setPhone(pn);

        request.setAttribute("bean",bean);  

        request.getRequestDispatcher("index.jsp");
        request.getRequestDispatcher("Register.jsp");


    }



}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<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_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>WebprojectTry</display-name>
  <welcome-file-list>

    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <description></description>
    <display-name>Controller</display-name>
    <servlet-name>Controller</servlet-name>
    <servlet-class>servlet.Controller</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>Controller</servlet-name>
    <url-pattern>/Controller</url-pattern>
  </servlet-mapping>
</web-app>
Was it helpful?

Solution

Ok, you can browse complete code at my GitHub account. It is working but I would personally used JPA for persistence.

Let start with controller, which contains doPost method. It just takes request parameters, constructs some bean and calls DAO to persist it to database. Once done, it sets a bean as request attribute and dispatches call to jsp. It means that once you open this jsp again, this bean will be not gone. Use session to store it across multiple calls.

public class Controller extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String name = request.getParameter("name");
        String phone = request.getParameter("phone");
        // todo check parameters

        User user = new User(name, phone);
        DAO dao = new DAO();
        dao.saveUser(user);
        request.setAttribute("USER", user);// consider using session
        // TODO handle errors

        RequestDispatcher dispatcher = request.getRequestDispatcher("register/index.jsp");
        dispatcher.forward(request, response);
    }
}

web.xml is easy:

<servlet>
    <servlet-name>RegistrationController</servlet-name>
    <servlet-class>cz.literak.sandbox.so.register.Controller</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>RegistrationController</servlet-name>
    <url-pattern>/RegistrationController</url-pattern>
</servlet-mapping>

DAO uses old plain JDBC to store the object in database table. I would favour using DataSource instead.

static {
    try {
        Class.forName("org.mariadb.jdbc.Driver");

// Class.forName("com.mysql.jdbc.Driver"); } catch (ClassNotFoundException e) { e.printStackTrace(); } }

public User findUser(String phone) {
    // todo
    return null;
}

//  DDL: CREATE TABLE user (name VARCHAR(100), phone VARCHAR(100))
public boolean saveUser(User user) throws ServletException {
    try (
         Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "secret");
         PreparedStatement ps = con.prepareStatement("INSERT INTO user VALUES(?,?)"))
    {
        ps.setString(1, user.getName());
        ps.setString(2, user.getPhone());
        return ps.execute();
    } catch (SQLException e) {
        throw new ServletException("DB operation failed", e);
    }
}

And finally jsp. It just checks if USER exists and then either displays registration form or welcome message.

<c:choose>
    <c:when test="${USER == null}">
        <form action="${pageContext.request.contextPath}/RegistrationController" method="post">
            <table>
                <tr>
                    <td>User name</td>
                    <td><input type="text" name="name" ></td>
                </tr>
                <tr>
                    <td>Phone</td>
                    <td><input type="text" name="phone"></td>
                </tr>
                <tr>
                    <td></td>
                    <td><input type="submit" value="submit"></td>
                </tr>
            </table>
        </form>
    </c:when>
    <c:otherwise>
        Welcome <c:out value="${USER.name}"/>
    </c:otherwise>
</c:choose>

I hope that you will not delete this question as it took me substantial amount of time to answer.

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