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About Ilias Tsagklis

Ilias Tsagklis
Ilias is a software developer turned online entrepreneur. He is co-founder and Executive Editor at Java Code Geeks.

Get/Set init Parameters in Servlet

In this example we are going to see how to get/set init parameters in a Servelt. Using init parameters you can specify several important aspects of your servlets that are going to be handled during requests service.

In short, to get/set init Parameters in Servlet you should:

  • Create public void init() function on your servlet.
  • Call getServletConfig().getInitParameterNames()
  • Use put(initParamName, initParamValue) to put parameters in your init parameter map.
  • In your doGet method use initParamsMap.entrySet().iterator() to get an Iterator an iterate through init parameters.
 
Let’s see the code snippets that follow:

package com.javacodegeeks.snippets.enterprise;

import java.io.IOException;
import java.io.PrintWriter;

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

public class GetSetInitParametersInServlet extends HttpServlet {

	private static final long serialVersionUID = -2128122335811219481L;

	private String paramName;
	private String paramValue;

	public void init() throws ServletException {
		paramName = "myparam";
		paramValue = getServletConfig().getInitParameter(paramName);
	}

	public void doGet(HttpServletRequest req, HttpServletResponse res) throws IOException {

		PrintWriter out = res.getWriter();
		res.setContentType("text/plain");

		out.write(paramName);
		out.write(" = ");
		out.write(paramValue);

		out.close();
	}

}

web.xml

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
  version="2.5">

	<display-name>JCG Snippets Web Project</display-name>

	<servlet>
		<servlet-name>JCG Snippets Application</servlet-name>
		<servlet-class>com.javacodegeeks.snippets.enterprise.GetSetInitParametersInServlet</servlet-class>
		<init-param>
			<param-name>myparam</param-name>
			<param-value>myvalue</param-value>
		</init-param>
	</servlet>

	<servlet-mapping>
		<servlet-name>JCG Snippets Application</servlet-name>
		<url-pattern>/jcgservlet</url-pattern>
	</servlet-mapping>

</web-app>

URL:

http://myhost:8080/jcgsnippets/jcgservlet

Output:

myparam = myvalue

This was an example on how to get/set init Parameters in Servlet.

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