We can achieve this by using annotations which you might have heard in core Java. It is data about data.
In a single line, we will be doing the servlet mapping to url pattern. Here is how:
This doesn't work in versions of tomcat that are < 7. So make sure that you have at least Tomcat 7.
Project structure
anser|__ index.html|__ WEB-INF|__ classes|__ MySer.java|__ MySer.class
Simple HTML Form - index.html
<html>
<body>
<form action="./hello">
<input type="text" name="username"></input>
<input type="submit"/>
</form>
</body>
</html>
Servlet Class with annotation
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.*;
@WebServlet(urlPatterns={"/hello"})
public class MySer extends HttpServlet
{
public void doGet(HttpServletRequest req,HttpServletResponse res) throws ServletException,IOException
{
PrintWriter pw=res.getWriter();
pw.println("<h1>Welcome "+req.getParameter("username")+"</h1>");
pw.close();
}
}
Here, at run time, the above servlet class is the one that will be executed for the url pattern /hello. So, whenever there is a request to the /hello then this class doGet() is activated. Isn't this great and simple?
Here you can also include multiple url-patterns for the same class as urlPatterns takes a String[]. For example,
Here either /hello or /welcome, this MySer will be executed.
@WebServlet(urlPatterns={"/hello","/welcome"})Here either /hello or /welcome, this MySer will be executed.
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