Sending Parameters to Servlet

 Sending Parameters to Servlet in Java

 

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Sometimes the user request may contain some data. It is sent through URL in the form of  name value pairs. This is generally known as a query string.

When URL submitted servlet will read this data from the query string, process it and sends a response back to the user.

 

Today, you are going to lean how to pass data and read it in servlet.

 Sending Parameters to Servlet using query string

→ In the URL after the servlet name query string  added.

→ Query string and URL separated by  ' ? ' .

→  with query string, we pass parameter name  values to servlet.

http://localhost:8080/FirstWebApplication/PostParameterServlet?name=abc

Here we are using a simple GenericServlet example.

A service method taking two parameters - request,response

Inside the service method, a PrintWriter object reference(out) is created. 

That point to the PrintWriter object, which is return by response.getWriter().

Using out object println() method we can display a message on client screen. 

Finally out.close() closes the stream.

 

 

Example:

PostParametersServlet.java 

import java.io.*;

import javax.servlet.*; 

public class PostParametersServlet extends GenericServlet{

 public void service(ServletRequest request,ServletReresponse response)
	throws ServletException,IoException{
 
	 PrintWriter out= response.getWriter(); 

        String pname= request.getParameter("name"); 

        out.println("Hello..!!" + pname); 

        out.close(); 

} 

}

Create the above servlet in web project, and add the servlet to web.xml

 

Open the Servlet URL in a browser and parameters along with URL as 

shown in below URL.

http://localhost:8080/FirstWebApplication/PostParameterServlet?name=abc

Output:

Hello abc 

Example2: 

import java.io.*;

import javax.servlet.*;

 

public class PostParametersServlet2 extends GenericServlet{

  public void service(ServletRequest req,ServletReresponse res)

      throws ServletException, IOException{

  PrintWriter out= res.getWriter();

  String sname= req.getParameter("t1");



  out.println("Hello..." + sname);

  out.close();

}

}