In this tutorial you will learn about the Servlet CRUD and its application with practical example.
Servlet CRUD
CRUD (Create,Read,Update,Delete) is the most important part of any application or project. In this article we will learn about CRUD. Let’s get understand it by an example.
Example :-
Before doing coding part we need to create database and table for the storage, in this example I have used mysql which is in phpmyadmin of Xampp. Check below image for table structure.
Here test is database name and emp_management is the table name.
Let’s start coding part. First we need to create project for this, index.html file will be auto created. Check below code for that and also other classes.
Note: Don’t forget to add MySQL JDBC Driver in your project like below image.
index.html
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<html> <head> <title>W3adda.com</title> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> </head> <body> <h1>Add Employee</h1> <form action="AddServlet" method="post"> <table> <tr><td>Name:</td><td><input type="text" name="name"/></td></tr> <tr><td>Password:</td><td><input type="password" name="password"/></td></tr> <tr><td>Email:</td><td><input type="email" name="email"/></td></tr> <tr><td>Country:</td><td> <select name="country" style="width:150px"> <option>India</option> <option>USA</option> <option>UK</option> <option>Other</option> </select> </td></tr> <tr><td colspan="2"><input type="submit" value="Add Employee"/></td></tr> </table> </form> <br/> <a href="ViewEmpServlet?page=1">view employees</a> </body> </html> |
Emp.java
This is our java bean class, from here we will set and get the data.2. Emp.java : This is our java bean class, from here we will set and get the data.
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package Model; public class Emp { private int id; private String name,password,email,country; 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; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public String getCountry() { return country; } public void setCountry(String country) { this.country = country; } } |
EmpDBHandler.java
This is very important part of this project, from here we will handle our all queries of database, database connection also be here. Check below code.
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import Model.Emp; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.util.ArrayList; import java.util.List; public class EmpDBHandler { public static Connection getConnection(){ Connection con=null; try{ Class.forName("com.mysql.jdbc.Driver"); con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", ""); }catch(Exception e){System.out.println(e);} return con; } public static int AddEmp(Emp e){ int status=0; try{ Connection con=EmpDBHandler.getConnection(); PreparedStatement ps=con.prepareStatement( "insert into emp_management(full_name,password,email,country) values (?,?,?,?)"); ps.setString(1,e.getName()); ps.setString(2,e.getPassword()); ps.setString(3,e.getEmail()); ps.setString(4,e.getCountry()); status=ps.executeUpdate(); con.close(); }catch(Exception ex){ex.printStackTrace();} return status; } public static int update(Emp e){ int status=0; try{ Connection con=EmpDBHandler.getConnection(); PreparedStatement ps=con.prepareStatement( "update emp_management set full_name=?,password=?,email=?,country=? where id=?"); ps.setString(1,e.getName()); ps.setString(2,e.getPassword()); ps.setString(3,e.getEmail()); ps.setString(4,e.getCountry()); ps.setInt(5,e.getId()); status=ps.executeUpdate(); con.close(); }catch(Exception ex){ex.printStackTrace();} return status; } public static int delete(int id){ int status=0; try{ Connection con=EmpDBHandler.getConnection(); PreparedStatement ps=con.prepareStatement("delete from emp_management where id=?"); ps.setInt(1,id); status=ps.executeUpdate(); con.close(); }catch(Exception e){e.printStackTrace();} return status; } public static Emp getEmployeeById(int id){ Emp e=new Emp(); try{ Connection con=EmpDBHandler.getConnection(); PreparedStatement ps=con.prepareStatement("select * from emp_management where id=?"); ps.setInt(1,id); ResultSet rs=ps.executeQuery(); if(rs.next()){ e.setId(rs.getInt(1)); e.setName(rs.getString(2)); e.setPassword(rs.getString(3)); e.setEmail(rs.getString(4)); e.setCountry(rs.getString(5)); } con.close(); }catch(Exception ex){ex.printStackTrace();} return e; } public static List<Emp> getAllEmployees(){ List<Emp> list=new ArrayList<Emp>(); try{ Connection con=EmpDBHandler.getConnection(); PreparedStatement ps=con.prepareStatement("select * from emp_management"); ResultSet rs=ps.executeQuery(); while(rs.next()){ Emp e=new Emp(); e.setId(rs.getInt(1)); e.setName(rs.getString(2)); e.setPassword(rs.getString(3)); e.setEmail(rs.getString(4)); e.setCountry(rs.getString(5)); list.add(e); } con.close(); }catch(Exception e){e.printStackTrace();} return list; } public static List<Emp> getRecords(int start,int total){ List<Emp> list=new ArrayList<Emp>(); try{ Connection con=getConnection(); PreparedStatement ps=con.prepareStatement("select * from emp_management limit "+(start-1)+","+total); ResultSet rs=ps.executeQuery(); while(rs.next()){ Emp e=new Emp(); e.setId(rs.getInt(1)); e.setName(rs.getString(2)); e.setEmail(rs.getString(4)); list.add(e); } con.close(); }catch(Exception e){System.out.println(e);} return list; } } |
AddServlet.java
From this class we will add employee which will inserted to database. Check below code.
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import Model.Emp; 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; public class AddServlet extends HttpServlet { /** * Processes requests for both HTTP <code>GET</code> and <code>POST</code> * methods. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=UTF-8"); } // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code."> /** * Handles the HTTP <code>GET</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); } /** * Handles the HTTP <code>POST</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); PrintWriter out=response.getWriter(); String name=request.getParameter("name"); String password=request.getParameter("password"); String email=request.getParameter("email"); String country=request.getParameter("country"); Emp e=new Emp(); e.setName(name); e.setPassword(password); e.setEmail(email); e.setCountry(country); int status=EmpDBHandler.AddEmp(e); if(status>0){ out.print("<p>Record saved successfully!</p>"); request.getRequestDispatcher("index.html").include(request, response); }else{ out.println("Sorry! unable to save record"); } out.close(); } /** * Returns a short description of the servlet. * * @return a String containing servlet description */ @Override public String getServletInfo() { return "Short description"; }// </editor-fold> } |
ViewEmpServlet.java
It will show employees list in the form of table which are added by you, from here you can also delete and update user details. Check below code.
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import Model.Emp; import java.io.IOException; import java.io.PrintWriter; import java.util.List; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * * @author Intel */ public class ViewEmpServlet extends HttpServlet { /** * Processes requests for both HTTP <code>GET</code> and <code>POST</code> * methods. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=UTF-8"); } // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code."> /** * Handles the HTTP <code>GET</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); PrintWriter out=response.getWriter(); String spageid=request.getParameter("page"); int pageid=Integer.parseInt(spageid); int total=5; if(pageid==1){} else{ pageid=pageid-1; pageid=pageid*total+1; } List<Emp> list=EmpDBHandler.getRecords(pageid,total); out.println("<a href='index.html'>Add Employee</a>"); out.print("<h1>W3adda EMP LIST Page No: "+spageid+"</h1>"); out.print("<table border='1' cellpadding='4' width='60%'>"); out.print("<tr><th>Id</th><th>Name</th><th>Email</th>"); for(Emp e:list){ out.print("<tr><td>"+e.getId()+"</td><td>"+e.getName()+"</td><td>"+e.getEmail()+"</td></tr>"); } out.print("</table>"); out.print("<a href='ViewEmpServlet?page=1'>1</a> "); out.print("<a href='ViewEmpServlet?page=2'>2</a> "); out.print("<a href='ViewEmpServlet?page=3'>3</a> "); out.close(); } /** * Handles the HTTP <code>POST</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); } /** * Returns a short description of the servlet. * * @return a String containing servlet description */ @Override public String getServletInfo() { return "Short description"; }// </editor-fold> } |
DeleteEmpServlet.java
When you run this project you will find an option in “View Employee” screen that is delete, which will redirect to DeleteEmpServlet.java class and delete the entry from table. Check below code.
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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; public class DeleteEmpServlet extends HttpServlet { /** * Processes requests for both HTTP <code>GET</code> and <code>POST</code> * methods. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=UTF-8"); } // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code."> /** * Handles the HTTP <code>GET</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); String sid=request.getParameter("id"); int id=Integer.parseInt(sid); EmpDBHandler.delete(id); response.sendRedirect("ViewEmpServlet?page=1"); } /** * Handles the HTTP <code>POST</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); } /** * Returns a short description of the servlet. * * @return a String containing servlet description */ @Override public String getServletInfo() { return "Short description"; }// </editor-fold> } |
UpdateEmpServlet.java
This is the class from where you can update the details of employee, You will get the form here which will be filled by previous entries of employee, when you edit and submit the details , it will redirect to the UpdateEmpServlet2.java class, which will update the data in the table. Check below code for this class.
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import Model.Emp; 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; public class UpdateEmpServlet extends HttpServlet { /** * Processes requests for both HTTP <code>GET</code> and <code>POST</code> * methods. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=UTF-8"); } // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code."> /** * Handles the HTTP <code>GET</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); PrintWriter out=response.getWriter(); out.println("<h1>Update Employee</h1>"); String sid=request.getParameter("id"); int id=Integer.parseInt(sid); Emp e=EmpDBHandler.getEmployeeById(id); out.print("<form action='UpdateEmpServlet2' method='post'>"); out.print("<table>"); out.print("<tr><td></td><td><input type='hidden' name='id' value='"+e.getId()+"'/></td></tr>"); out.print("<tr><td>Name:</td><td><input type='text' name='name' value='"+e.getName()+"'/></td></tr>"); out.print("<tr><td>Password:</td><td><input type='password' name='password' value='"+e.getPassword()+"'/></td></tr>"); out.print("<tr><td>Email:</td><td><input type='email' name='email' value='"+e.getEmail()+"'/></td></tr>"); out.print("<tr><td>Country:</td><td>"); out.print("<select name='country' style='width:150px'>"); out.print("<option>India</option>"); out.print("<option>USA</option>"); out.print("<option>UK</option>"); out.print("<option>Other</option>"); out.print("</select>"); out.print("</td></tr>"); out.print("<tr><td colspan='2'><input type='submit' value='Update'/></td></tr>"); out.print("</table>"); out.print("</form>"); out.close(); } /** * Handles the HTTP <code>POST</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); } /** * Returns a short description of the servlet. * * @return a String containing servlet description */ @Override public String getServletInfo() { return "Short description"; }// </editor-fold> } |
UpdateEmpServlet2.java
As I explained above that this servlet will be used for update the employee details in the table, check below code for this class.
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import Model.Emp; 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; public class UpdateEmpServlet2 extends HttpServlet { /** * Processes requests for both HTTP <code>GET</code> and <code>POST</code> * methods. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=UTF-8"); } // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code."> /** * Handles the HTTP <code>GET</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); } /** * Handles the HTTP <code>POST</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); PrintWriter out=response.getWriter(); String sid=request.getParameter("id"); int id=Integer.parseInt(sid); String name=request.getParameter("name"); String password=request.getParameter("password"); String email=request.getParameter("email"); String country=request.getParameter("country"); Emp e=new Emp(); e.setId(id); e.setName(name); e.setPassword(password); e.setEmail(email); e.setCountry(country); int status=EmpDBHandler.update(e); if(status>0){ response.sendRedirect("ViewEmpServlet?page=1"); }else{ out.println("Sorry! unable to update record"); } out.close(); } /** * Returns a short description of the servlet. * * @return a String containing servlet description */ @Override public String getServletInfo() { return "Short description"; }// </editor-fold> } |
Output:-
So we are done with coding now check one by one screenshots of this project.
Index2.html
After Adding Employee
Database screenshot after adding employee.
View Employee screenshot.
Update Screenshot : On Update screeshot.
After update and add one more employee.
Delete: Post deletion result will be like below image
After insertion of multiple records.
So we are done with this project, link of this project is below. You can simply download this project by below link. Here we can see there are many records in table so in next article we will make them in pagination. In short we will divide our data in pages. Check Next article for this.
