Get all Request Parameters in Servlet (original) (raw)

With this tutorial we shall show you how to get all requests parameters in a Java Servlet. This the most basic step you have to consider when developing a Servelt application because HTTP is based mostly on parameters exchange.

Basically in order to get all Request Parameters in Servlet, one should take the following steps:

Create a handleRequest method so you can use it both in doGet and doPost methods.
Use HttpServletRequest.getParameterNames to get an Enumeration of parameter names.
Use HttpServletRequest.getParameterValues(paramName) to get the parameters values.

Let’s see the simple code snippets that follow:

package com.javacodegeeks.snippets.enterprise;

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

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

public class GetAllRequestParametersInServlet extends HttpServlet {

private static final long serialVersionUID = -2128122335811219481L;

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

public void doPost(HttpServletRequest req, HttpServletResponse res) throws IOException {
    handleRequest(req, res);
}

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

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

    Enumeration<String> parameterNames = req.getParameterNames();

    while (parameterNames.hasMoreElements()) {

        String paramName = parameterNames.nextElement();
        out.write(paramName);
        out.write("n");

        String[] paramValues = req.getParameterValues(paramName);
        for (int i = 0; i < paramValues.length; i++) {
            String paramValue = paramValues[i];
            out.write("t" + paramValue);
            out.write("n");
        }

    }

    out.close();

}

}

web.xml

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

<servlet>
    <servlet-name>JCG Snippets Application</servlet-name>
    <servlet-class>com.javacodegeeks.snippets.enterprise.GetAllRequestParametersInServlet</servlet-class>
</servlet>

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

URL:

http://myhost:8080/jcgsnippets/jcgservlet?param1=paramvalue1&param2=paramvalue2a&param2=paramvalue2b

Output:

param2
    paramvalue2a
    paramvalue2b
param1
    paramvalue1

This was an example on how to get all Request Parameters in Servlet.

Byron is a master software engineer working in the IT and Telecom domains. He is an applications developer in a wide variety of applications/services. He is currently acting as the team leader and technical architect for a proprietary service creation and integration platform for both the IT and Telecom industries in addition to a in-house big data real-time analytics solution. He is always fascinated by SOA, middleware services and mobile development. Byron is co-founder and Executive Editor at Java Code Geeks.