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How to get parameter names from servlet request?

This example show you how to obtain parameter name from servlet request. By calling request.getParameterNames() you will get an Enumeration object by iterating this object you can get the parameter names.

package com.javacoderanch.example.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;

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

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

	public ParameterName() {
		super();
	}

	protected void doGet(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		
		PrintWriter pw = response.getWriter();

                //
                // Let's obtains parameters name here! 
                //
		Enumeration enumeration = request.getParameterNames();
		while (enumeration.hasMoreElements()) {
			String parameterName = (String) enumeration.nextElement();
			pw.println("Parameter = " + parameterName);
		}
		pw.close();
	}

	protected void doPost(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
	}
}

When you call the servlet and pass some parameters you get the parameter name echoed on the web browser.

http://localhost:8080/java-web-examples/ParameterName?txid=001&item=10&price=1000

Parameter = price
Parameter = item
Parameter = txid