Java ppt

Defination:
 servlet is a java class that extends the
functionality of web server.
Eg:
 mail server
servlet is a class that performs virus scan to attached files

Benefits
 only one copy of servlet is loaded into jvm.
 each request begins a new thread to servlet process.
◙ save time
◙ response time increases
◙ it is scalable

Servlet implementation:
 servlet use class and interface from 2 package
◘ javax.servlet
 It contains classes to support generic protocol
◘ javax.servlet.http
 It extends classes in servlet package to add HTTP sapecific
functionality.

Servlet API :
o Servlet interface
o Genericservlet class
o HTTPservletrequest interface
o HTTPservletrequest interface
o Cookie class
o HTTPsession interrface
o single threadmodel interface
o servletexception class
o unavailableexception class
o servlettcontext interfave
o serrvletconfig interrface

Servlet interface:
 Every servlet must implements the javax.servlet interface
 It can implement in 2 ways:
◙ Directly implementing interface
◙ Extending any of 2 classes:
◙ javax.serrvlet.genricservlet
◙ javax.servlet.http.HTTPservlet

Methods:
◘ Init()
◘ Service()
◘ Destroy()
◘ Getservletinfo()
◘ Getservletconfig()

Service()
syntax:
 public abstract voidservice(servletrequest req,
servletresponse res)throws
servletException,IOException
◙ it is called whenever the request is made
◙it must be overridden in servlet
◙ it receives request via servletrequest and sends
response via servlet response

HTTP servlet
 It is an abstract class that is used for developing
HTTpservlets.
 It dose not override the service() method.
 It override doget() to handle GET requests and dopost()to
handle POST requests

Methods:
o serrvice()
o doget()
o dopost()
o dodelete()
o dooption()
o do put()
o do trace()

do get() or do post()
o protected void doget(HTTPServletRequest req
HTTPServletResponse res)throws servletException,IOException
o protected void dopost(HTTP ServletRequest
req,HTTPservletresponse res) throws
servletException,IOException

public class SessionServlet extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse res) throws IOException
{
res.setContentType("text/html");
OutputStream out = res.getOutputStream();
PrintWriter pw = new PrintWriter(new OutputStreamWriter(out));
HttpSession session = req.getSession(false);
if (session == null) {
session=req.getSession(true);
session.putValue ("VisitCount", "1");
}
pw.println("<html><body><pre>");
pw.println("session.isNew()="+session.isNew());
pw.println("session.getCreationTime()="+ new java.util.Date(
session.getCreationTime()));
pw.println("session.getID()="+session.getId());
pw.println("session.getLastAccessedTime()=" + new
java.util.Date(session.getLastAccessedTime()));
String strCount = (String) session.getValue("VisitCount");
pw.println("No. of times visited = " + strCount);
int count = Integer.parseInt(strCount); count++;
session.putValue("VisitCount", Integer.toString(count));
pw.println ("</pre></body></html>");
pw.flush();
}
}

Java ppt

Recommended

Recommended

More Related Content

What's hot

What's hot (17)

Similar to Java ppt

Similar to Java ppt (20)

More from renukarenuka9

More from renukarenuka9 (20)

Recently uploaded

Recently uploaded (20)

Java ppt