J2EE
This page is for students who just step in to J2EE(Java Two Enterprise Edition) to learn struts,servlet,Jsp,Hibernate and Springs etc.If you are a good Programmer Just contribute your programs or projects in Java,J2ee to help other students.
SERVLET HOW TO RUN
•Servlets are Java programming language objects that dynamically process requests and construct responses.
Servlet example for printing random values with Explanation
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class colorservlet extends HttpServlet
{
public void doGet(HttpServletRequest
request,HttpServletResponse response)throws ServletException,IOException
{
String color=request.getParameter(”color”);
response.setContentType(”text/html”);
PrintWriter pw=response.getWriter();
pw.println(”
<div>
<div><strong>The selected color is:”);
pw.println(color);
pw.close();
}
}
Step1:
To run servlet You need to compile it first for that you need any of the Jar files given below
1.servlet-api.jar (included in tomcat/lib) <a href=”http://tomcat.apache.org/download-55.cgi”>Download Tomcat</a>
or
2.Jsdk.jar(included in jsdk2.0 or later)<a href=”http://java.sun.com/products/servlet/
download.html”>Download from sun site</a>
After downloading installed it and give classpath for example if you are installing it in the c:/tomcat 5.5/”
then you had to assign classpath as
set classpath=c:/tomcat5.5/common/lib/servlet-api.jar;and now compile your program asusual like javac
colorservlet.java.
Step2:
To run serlvet you need to create a web.xml file
sample web.xml file for helloworld
<web-app>
<servlet>
<servlet-name>colorservlet</servlet-name>
<servlet-class>colorservlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>colorservlet</servlet-name>
<url-pattern>/colorservlet</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>colorservlet.html</welcome-file>
</welcome-file-list>
</web-app>
Now create colorservlet.html
<html>
<body>
<center>
<form name=”form1″ method=”get”
action=”colorservlet”>
<b>Color:</b>
<select name=”color” size=”1″>
<option value=”red”>Red</option>
<option value=”green”>Green</option>
<option value=”yellow”>Yellow</option>
</select>
<br><br>
<input type=submit value=”submit”>
</form>
</body>
</html>
Your folder structure will look below
colorservlet folder(inside webapps of tomcat installation folder)inside coloservlet folder it look like below.
=>WEB-INF=>classes=>class files of servlet
=>lib(jar files servlet-api.jar)
=>web.xml
=>colorservlet.html
Step3 :
goto
http://localhost:8080/colorservlet/
and run the program
redirect page using jsp to another page
username and password if login is correct it redirect to somepage.jsp if password is wrong it return back to login page
Note:Create database “s2sgateway” in mysql as i did in mysql(use any database) and create a table named “admin” with username and password
Login.html
<html><head>
<script type="text/javascript">
function check()
{
if(document.f.un.value=="" || document.f.pw.value=="")
{
alert("Enter details");
return false;
}
else
{
return true;
}
}
</script>
</head>
<body>
<form name="f" method="get" action="login.jsp">
<font color="red">
<marquee align="left" bgcolor="blue">LOGIN
FORM</marquee>
<br><br>
<center>
USERNAME: <input type="text" name="un"></center>
<center>PASSWORD:
<input type="password" name="pw"></center>
<center>
<input type="submit"
value="SIGN IN" onclick="return check()" /></center></font>
</form>
</body></html>
Now create action page login.jsp
<%@ page language="java"
import="java.sql.*,java.util.*"%>
<%String name=request.getParameter("un");
String pwd=request.getParameter("pw");
try{
Connection
con=DriverManager.getConnection
("jdbc:mysql://localhost/s2sgateway","username",
"password");
Statement st=con.createStatement();
ResultSet rs=st.executeQuery("select * from admin where username='"+name+"'");
while(rs.next())
{
if((rs.getString(1).equalsIgnoreCase(name))&&(r
s.getString(2).equalsIgnoreCase(pwd)))
{
out.println("WELCOME,Webmaster");
response.sendRedirect("somepage.jsp");
}
else
{
response.sendRedirect("login.html");
}
}
}catch(Exception e)
{
out.println(e);
}
%>
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