getRemoteAddr() method is defined in ServletRequest interface from javax.servlet package inherited by HttpServletRequest.
With this method, the servlet programmer can know the IP address of the client from which the request came.
Let us see what Java API says about this method.
- String getRemoteAddr(): Returns the Internet Protocol (IP) address of the client or last proxy that sent the request. For HTTP servlets, same as the value of the CGI variable REMOTE_ADDR.
The method getRemoteAddr() returns the IP address of the cleint as a string.
Let us see the output by writing a program.
HTML Program: ClientData.html
web.xml entry for ClientInformation servlet
efgh
ClientInformation
efgh
/jasmine
Servelet Program: ClientInformation.java
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class ClientInformation extends HttpServlet
{
public void service(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException
{
res.setContentType("text/html");
PrintWriter out = res.getWriter();
String str = req.getRemoteAddr();
out.println("req.getRemoteAddr() : " + str);
out.close();
}
}

Output screen of ClientData.html with text field filled up. Ofcourse, this does not have any relevance with the method getRemoreAddr() method

Output screen when submit button is clicked.
Observe, the IP address as 127.0.0.1
To know the name of the client system (not IP address), a separate program exists: getRemoteHost() Method Example.
By the way thanks for the example given above.