I am learning to connect my servlet to database. I have two columns in my db (Username,Password). I want to create a program that access the database compares the User/Pass (send via the user form html ) with the values in db columns. When i try to login , nothing shows up on screen .
Files:
LoginServlet.java
import javax.servlet.http.*;
import javax.servlet.*;
import java.io.*;
import java.sql.*;
public class LoginServlet extends HttpServlet{
public void init(){}
Connection con;
Statement st;
ResultSet rs;
public void service(HttpServletRequest req, HttpServletResponse res){
try{
res.setContentType("text/html");
PrintWriter out=res.getWriter();
out.println("<html><body>");
out.println("<p>Servlet is loading</p>");
String TheUser=req.getParameter("username");
String ThePass=req.getParameter("password");
try{
Class.forName("oracle.jdbc.driver.OracleDriver");
con=DriverManager.getConnection("jdbc:oracle:thin:#localhost:1521:xe","system","pass");
st=con.createStatement();
rs=st.executeQuery("select Username,Password from AllUsers");
String compareUser=rs.getString(1);
String comparePass=rs.getString(2);
if(TheUser.equals(compareUser)||ThePass.equals(comparePass)){
out.println("<p>You are logged in as " + compareUser+" </p>");
}
else
out.println("Wrong Combination");
}
}catch(Exception e){}
}catch(ClassNotFoundException|IOException|ServletException f){
f.printStackTrace();
}
out.println("</html></body>");
out.close();
}
public void destroy(){}
}
This File Compiles and deployed.
web.xml:
<web-app>
<servlet>
<servlet-name>SignUpServlet</servlet-name>
<servlet-class>SignUpServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>SignUpServlet</servlet-name>
<url-pattern>/SignUp</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
</web-app>
log.html:
<html>
<body>
<form name='loginForm' method='post' action='login'>
Enter Username:
<input type='text' name='username'>
</br>
Enter Password:
<input type='password' name='password'>
</br>
<input type="submit" value="Submit">
</form>
</body>
</html>
P.S: Servlet is loading. The <p>Servlet is loading </p> tag shows up on browser.
Ok so i did it. After many hours of hit n try. I figured out that the db cursor was never on the first records of the table , that's why it didnt show up.
I wrapped the code in a while statement:
rs=st.executeQuery("select Username,Password from AllUsers");
while(rs.next()){
String compareUser=rs.getString(1);
String comparePass=rs.getString(2);
if(TheUser.equals(compareUser)||ThePass.equals(comparePass)){
out.println("<p>You are logged in as " +compareUser+"</p>");
rs.close();
st.close();
con.close();
}
else{
out.println("<p>Wrong Combination</p>");
out.println("</br><a href='log.html'>Login</a></p>");
rs.close();
st.close();
con.close();
}
}
}catch(Exception e){
e.printStackTrace();
}
I hope if anyone else runs into this problem, this could help.
Related
I am trying this for a while but every time when i try to run on browser it shows nothing, not even an error.
"index.html" file
<html>
<head>
<title>Register form</title>
</head>
<body>
<form method="post" action="register">
Name:<input type="text" name="name" /><br/>
Email ID:<input type="text" name="email" /><br/>
Password:<input type="text" name="pass" /><br/>
<input type="submit" value="register" />
</form>
</body>
"web.xml" file
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" >
<servlet>
<servlet-name>register</servlet-name>
<servlet-class>Register</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>register</servlet-name>
<url-pattern>/register</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
</welcome-file-list>
</web-app>
"Register.java" file
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
public class Register extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
String name = request.getParameter("name");
String email = request.getParameter("email");
String pass = request.getParameter("pass");
try{
//loading drivers for mysql
Class.forName("com.mysql.jdbc.Driver");
//creating connection with the database
Connection con=DriverManager.getConnection
("jdbc:mysql:/ /localhost:3306/db","myuser","1234");
PreparedStatement ps=con.prepareStatement
("insert into Student values(?,?,?)");
ps.setString(1, name);
ps.setString(2, email);
ps.setString(3, pass);
int i=ps.executeUpdate();
if(i>0)
{
out.println("You are sucessfully registered");
}
}
catch(Exception se)
{
se.printStackTrace();
}
}
}
This image is after i entered the details, and there is no data stored in my database
This is the error showing in cmd
I am using JDK 9 which have no "ext" file in the JRE so i included JDBC driver file through command line.
I have created database 'db' in mysql and table name 'student'.
I don't know where is the problem. Please help me!!
You do not close Connection and PreparedStatement.
Best use try-with-resources for that. There was a space in the connection URL.
The other problem was already mentioned.
try (Connection con=DriverManager.getConnection
("jdbc:mysql://localhost:3306/db","myuser","1234");
PreparedStatement ps=con.prepareStatement
("insert into Student (name,email,pass) values(?,?,?)")) {
ps.setString(1, name);
ps.setString(2, email);
ps.setString(3, pass);
ps.executeUpdate();
} catch(Exception se) {
se.printStackTrace();
}
Your form method is post:
<form method="post" action="register">
And in your servlet you only have a doGet.
Change your form method to get:
<form method="get" action="register">
Servlet doGet:
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String name = request.getParameter("name");
String email = request.getParameter("email");
String pass = request.getParameter("pass");
try{
//loading drivers for mysql
Class.forName("com.mysql.jdbc.Driver");
//creating connection with the database
Connection con=DriverManager.getConnection
("jdbc:mysql:/ /localhost:3306/db","myuser","1234");
PreparedStatement ps=con.prepareStatement
("insert into Student (name,email,pass) values(?,?,?);");
ps.setString(1, name);
ps.setString(2, email);
ps.setString(3, pass);
ps.executeUpdate();
}catch(Exception se){
se.printStackTrace();
}
//redirect user back to index
RequestDispatcher rd=request.getRequestDispatcher("index.html");
rd.forward(request,response);
}
}
package mycode;
import java.sql.*
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 Login extends HttpServlet {
private static final long serialVersionUID = -4546189621945422719L;
String URL = "jdbc:mysql://127.0.0.1";
String USER = "root";
String PASS = "1234";
#Override
protected void doGet(HttpServletRequest req,HttpServletResponse res)
throws IOException,ServletException{
}
public void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
String username = req.getParameter("username");
String password = req.getParameter("password");
res.setContentType("text/html");
PrintWriter out = res.getWriter();
try {
Connection con = DriverManager.getConnection(URL, USER, PASS);
String sql = "INSERT INTO cloud.cloud_table (Username,Password)" +
"VALUES (?, ?)";
PreparedStatement pst = con.prepareStatement(sql);
pst.setString(1, username);
pst.setString(2, password);
pst.executeUpdate();
out.println("<html><body>");
out.println("THANKS FOR CREATING AN ACCOUNT");
out.println("</body></html>");
}
catch (SQLException ex) {
ex.printStackTrace();
}
}
}
<?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_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>Login</display-name>
<servlet>
<servlet-name>Login</servlet-name>
<servlet-class>mycode.Login</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Login</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
+----------+----------+
| Username | Password |
+----------+----------+
| | |
+----------+----------+
<form action="login" method="GET">
<div>
<h4>Please enter your password and username</h4>
</div>
<div>
Username <input name="username" type="text" />
</div>
<div>
Password <input name="password" type="text" />
</div>
<div>
<input type="submit" value="Submit" />
</div>
</form>
Using java and tomcat, I have a simple form that takes in a username and password. I want to be able to retrieve the username and password from the form and insert it into a mysql database. However, right now after clicking the submit button on the form, nothing happens and the database is not updated. The database connection is working fine so I am not sure what the problem is right now. Any help would be appreciated.
You are calling your GET method from the HTML form.
Change your action to POST.
<form action="login" method="POST">
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I am creating a payroll system. I have a database which contains employee_id and password. My index.html is the login page, where you enter an employee_id and password and the database checks to see if the details are correct and if it is, then the Welcome.java servlet takes you to a page which prints "Welcome user".
What I want is, when an employee logs in, it takes them to a page with the following buttons instead of a screen which simply says "Welcome user":
View personal information, View payslip information, change password
I do not know how to do this.
Below are my files.
index.html
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Login</title>
</head>
<body>
<form action="login" method="post">
<h3>
Employee Login
</h3>
<b>Employee ID:</b> <br>
<input type="text"name="employee_id" size="20"><br><br>
<b>Password:</b><br>
<input type="password" name="password" size="20"><br><br>
<input type="submit" value="Login"><br><br>
</form>
</body>
</html>
Login.java (servlet)
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
public class Login extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
String employee_id = request.getParameter("employee_id");
String password = request.getParameter("password");
if(Validate.checkUser(employee_id, password)) {
RequestDispatcher rs = request.getRequestDispatcher("Welcome");
rs.forward(request, response);
}
else
{
out.println("Employee ID or Password is incorrect. Please try again.");
RequestDispatcher rs = request.getRequestDispatcher("index.html");
rs.include(request, response);
}
}
}
Validate.java (class file)
import java.sql.*;
public class Validate
{
public static boolean checkUser(String employee_id, String password)
{
boolean st = false;
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/payroll_system", "root", "");
PreparedStatement ps = con.prepareStatement("select * from employee_login where employeeID = ? and pwd = ?");
ps.setString(1, employee_id);
ps.setString(2, password);
ResultSet rs =ps.executeQuery();
st = rs.next();
}catch(Exception e)
{
e.printStackTrace();
}
return st;
}
}
Welcome.java (servlet)
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
public class Welcome extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
out.println("Welcome user");
}
}
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" >
<servlet>
<servlet-name>login</servlet-name>
<servlet-class>Login</servlet-class>
</servlet>
<servlet>
<servlet-name>Welcome</servlet-name>
<servlet-class>Welcome</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>login</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>Welcome</servlet-name>
<url-pattern>/Welcome</url-pattern>
</servlet-mapping>
</web-app>
You have to change one line of code of login servlet RequestDispatcher rs = request.getRequestDispatcher("Welcome"); as RequestDispatcher rs = request.getRequestDispatcher("Options");
and create a html file of creating 3 buttons.
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Options</title>
</head>
<body>
<form action="Mainservlet" method="post">
<h3>
Options
</h3>
<input type="submit" value="Personalinformation" name="pi">
<br>
<br>
<input type="submit" value="PayslipInformation" name="psi">
<br>
<br>
<input type="submit" value="ChangePassword" name="cp">
<br>
<br>
</form>
</body>
</html>
In mainservlet
if(request.getParameter("pi") != null) {
// Invoke PersonalInformation's job here.
} else if (request.getParameter("psi") != null) {
// Invoke PayslipInformation's job here.
}else if (request.getParameter("cp") != null) {
// Invoke ChangePassword's job here.
}
Create an html or jsp page with your buttons and other content, then redirect from login servlet to your page instead of welcome servlet through request dispatcher or just by response.sendRedirect() method.
I am trying to make a login servlet. I have a login.jsp from where i take data using a form, a LoginServlet where i use HttpSession and finally my web.xml
I searched here in stackoverflow and i corrected some mistakes i found. Even though my LoginServlet can't be found:
HTTP Status 404 - /test_pages/main_pages/com.register/LoginServlet
type: Status report
message: /test_pages/main_pages/com.register/LoginServlet
description: The requested resource is not available.
I saw in Status 404 that the path to my servlet is this:/test_pages/main_pages/com.register/LoginServlet
This is wrong path. My servlet is not in main_pages. I am writing in ecipse. I have to make a project in order to run all thes in apache tomcat and it confuses me a lot. My LoginServlet is in Java Resources/src/com.register. "com.register" is my package.
Can you tell me a proper way to write the action in my form? Do you think the problem is somewhere else? Please help me! Thanks in advance!
This is my code:
login.jsp
.
.
.
<form action="com.register/LoginServlet" method="post">
<p>
<label id="upodeiksh">username</label>
<br />
<input type="text" name="username" id="koutaki" required/>
</p>
<br />
<p>
<label id="upodeiksh">password</label>
<br />
<input type="password" name="password" id="koutaki" required/>
</p>
<br />
<input type="submit" name="upload" value="login" id="submit_button"/>
</form>
LoginServlet.java
package com.register;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.*;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class LoginServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/jsp");
PrintWriter out=response.getWriter();
request.getRequestDispatcher("test.jsp").include(request, response);
String name=request.getParameter("username");
String password=request.getParameter("password");
String psw = null;
Connection con = null;
PreparedStatement pr = null;
ResultSet rs = null;
try
{
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection("jdbc:mysql://localhost:3306/ted","root","1234");
pr = con.prepareStatement("select * from ted.users where usrname=?;");
pr.setString(1, name);
rs = pr.executeQuery();
//An den brethei to onoma
if(rs == null)
{
out.print("Το όνομα χρήστη : "+name+" δεν υπάρχει");
request.getRequestDispatcher("main_pages/login.jsp").include(request, response);
}
else
{
//An brethei to onoma
while(rs.next())
{
psw = rs.getString("psw");
}
if(psw != password)
{
out.print("Λάθος κωδικός πρόσβασης");
request.getRequestDispatcher("main_pages/login.jsp").include(request, response);
}
else if(psw == password)
{
out.print("Γεια");
HttpSession session=request.getSession();
session.setAttribute("name",name);
}
}
}
catch (Exception e)
{
System.out.println("The error is=="+e.getMessage());
}
finally
{
try
{
con.close();
}
catch (SQLException e)
{
e.printStackTrace();
}
}
}
}
web.xml
.
.
<servlet>
<description></description>
<display-name>LoginServlet</display-name>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>com.register.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/LoginServlet</url-pattern>
</servlet-mapping>
<servlet>
.
.
Your servlet mapping is wrong. Change your form action like this
<form action="LoginServlet" method="post">
This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
Calling servlet from HTML form, but servlet is never invoked
I'm calling servlet from html form, servlet takes the form data and it will insert that form data into database.But when i click the submit button error page is coming. Please help whats wrong in my servlet code.
My html code:
<html>
<head>
<title> Sign Up </title>
</head>
<body>
<form action="servlet/Loginservlet" method="post" >
<font size='5'>Create your Account:</font><br/><br>
<label for="username" accesskey="u" style="padding-left:3px;">User Name: </label>
<input type="text" style="background-color:#ffffff;margin-left:14px;padding-top:7px;border-width:0px;margin-top:6px;padding-right:85px;" id="username" name="username" tabindex="1"><br/><br>
<label for="password" accesskey="p" style="padding-left:4px;">Password: </label>
<input type="password" style="background-color:#ffffff;margin-left:14px;padding-top:7px;border-width:0px;padding-right:85px;" id="password" name="pasword" tabindex="2"><br/><br>
<input type="submit" value="Submit" style="margin-left:164px;"/>
<input type="reset" value="Reset" style="margin-left:17px;"/>
</form>
</body>
</html>
My servlet code:
import javax.servlet.http.HttpServlet;
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class Loginservlet extends HttpServlet {
public void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
System.out.println("login servlet");
String connectionURL = "jdbc:mysql://localhost:3306/mysql";
Connection connection = null;
res.setContentType("text/html");
PrintWriter out = res.getWriter();
String username = req.getParameter("username");
String password = req.getParameter("password");
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(connectionURL, "root", "root");
String sql = "insert into signup values (?,?)";
PreparedStatement pst = connection.prepareStatement(sql);
pst.setString(1, username);
pst.setString(2, password);
int numRowsChanged = pst.executeUpdate();
out.println(" Data has been submitted ");
pst.close();
} catch (ClassNotFoundException e) {
out.println("Couldn't load database driver: " + e.getMessage());
} catch (SQLException e) {
out.println("SQLException caught: " + e.getMessage());
} catch (Exception e) {
out.println(e);
} finally {
try {
if (connection != null) {
connection.close();
}
} catch (SQLException ignored) {
out.println(ignored);
}
}
}
}
My web.xml:
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<servlet>
<servlet-name>login</servlet-name>
<servlet-class>Loginservlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>login</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
</web-app>
I think, mistake is here: <form action="servlet/Loginservlet"
Try this <form action="/<your-app-name>/login"
since in form action you have given servlet/Loginservlet . you should map same in web.xml like
<url-pattern>/servlet/Loginservlet</url-pattern>
or change in the form like
action='login'
you can do any one of above.
try this
<form action="login" method="post" >
you servlet url is
<url-pattern>/login</url-pattern>
When you run your web application for local host then the url like
localhost:8080/test
then the test is the name of your application name which contain your web application into the web dir. Now suppose you create the index file then it will run index file from this only and another page url like
localhost:8080/test/page1.html
now from page1.html you start your login page then the link looks like for servlet is
localhost:8080/test/login
as define the url pattern for specific servlet that url you have to set for calling the specific servlet like above. this url will hide the actual servlet for the client you can set anything in url pattern