how can I call another servlet from an action inside my servlet

[Moieen Khatri]

Hi,

I have a servlet class in which I have an export button.When I click on the export button it should call another servlet which would create a report of the data from the database.I am not sure how to call the new Servlet through the submit button action inside my servlet.Can some one please help me?

out.println("<table><td><br><FORM METHOD=POST ACTION='exportdbServlet'>");
 out.println("<input type=submit VALUE="+ "\"Export Data\"> <br></td></form></table>");

On click of Export Data button.The request should be passed to the exportdbservlet which would create the report.At the moment I cannot call the exportdbservlet.The code of the new servlet is pasted below:

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ExportdbServlet extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet {

private static final long serialVersionUID = 1L;
	
	 
	 
	public ExportdbServlet() {
		super();
		
		System.out.println("export servlet called");
		// TODO Auto-generated constructor stub
	}
	
	protected void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException,IOException
	{
		System.out.println("export dopost called");
	}

}

Please can some one advice on this issue?

Thanks

[ujjwal soni]

Hi,

As you said you want to call a servlet, then you need to create a new servlet, describe it in web.xml and call the servlet URL in form post parameter.

See for example i have one main servlet called TestOne

 <servlet>
        <servlet-name>TestOne</servlet-name>
        <servlet-class>TestOne</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>TestOne</servlet-name>
        <url-pattern>/TestOne</url-pattern>
    </servlet-mapping>

Now, i want to call a new servlet called TestTwo so, i would define this in web.xml something like this,

<servlet>
        <servlet-name>TestTwo</servlet-name>
        <servlet-class>TestTwo</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>TestTwo</servlet-name>
        <url-pattern>/TestTwo</url-pattern>
    </servlet-mapping>

Create a class called TestOne.java and TestTwo.java

Now, on my jsp page called as testone.jsp

<form method=post action="/TestTwo">
<input type=submit>
</form>

will call the second servlet

[Milan Jagatiya]

use RequestDispatcher.

http://java.sun.com/products/servlet/2.2/javadoc/

[ujjwal soni]

Check out below example

in the doGet method compare this parameter and call the apropiate method inside the forwarded servlet, something like this:

public class servlet_that_forward extends HttpServlet {
public void doPost (HttpServletRequest request, 
HttpServletResponse response) throws ServletException, 
IOException {
RequestDispatcher RD = getServletContext).getRequestDispatcher("forwarded_servlet?param=method1");
RD.forward();
}
}
public class forwarded_servlet extends HttpServlet {
public void doGet (HttpServletRequest request, 
HttpServletResponse response) throws ServletException, IOException {
String param;
param = request.getParameter("param");
if (param.compareTo("method1")==0) {
method1(); 
}
}
public void method1() {
//Do something
}
}

Hope that can be helpful,

[Moieen Khatri]

Thanks for the reply!

How can I call this on the submit inside my existing servlet? What should I write for submit button?

out.println("<table><td><br><FORM METHOD=exportdb ACTION='analyzeDocBase'>");
 out.println("<input name ='exportHistory' type=submit VALUE="+ "\"Export Data\"> <br></td></form></table>");

Please can you explain how can I call your code from the above submit button?

Thanks

[David Newton]

What? You don't call the form submit from within the Java that creates the HTML that emits the form submit button.

The *user* calls the servlet (or whatever) when they click the submit button. You might want to find a basic tutorial on how web applications work to clear up some misunderstandings regarding the client and server sides and how they interact.

[Moieen Khatri]

Can I use RequestForwarding or RequestDispatching on click of the submit button? If yes,how can I forward the existing omc object to the new servlet which will print the html?

Thanks

[David Newton]

...

We're not getting anywhere here.

1) User clicks "submit" button--this makes a request to a servlet.
2) Servlet runs, processes info from the DB, and returns something.

That's all there is to it.

Here's a more detailed sequence of events:

1) User requests the servlet that generates the HTML you've shown.
2) That servlet returns a bunch of HTML including a submit button.
3) The browser renders that HTML, creating a form on a web page.
4) User sees the form, clicks the "submit" button.
5) That makes a request to another servlet
6) That other servlet reads stuff from the DB and either renders its own HTML (IMO not a good idea) or forwards to a JSP that renders HTML.

I'm not sure what else to tell you.

[Moieen Khatri]

Hi,

I resolved this issue by using request dispatch to a jsp.It works now for me.

Thanks for the help provided!