getting all request parameters in servlet

before this we have used request.getParameter(String) which is used to get a single request parameter value.
Now if we want to get all parameter names then we have to use request.getParameterNames()
it returns Enumeration of String objects of all parameter names.
After getting all parameter names we can get its value using request.getParameter(String) .
request.getParameterNames() is useful we have large number of parameters are used in request.
Following example is used to explain the above concepts.

Project Explorer:

index.jsp

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html">

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>Getting all parameters in servlet</title>
    </head>
    <body>
        <h1>Getting all parameters in servlet</h1>
        <form action="allparameters" method="post">
            First Name:<br/>
            <input type="text" name="fname" placeholder="first name"/><br/>
            Middle Name:<br/>
            <input type="text" name="midname" placeholder="middle name"/><br/>
            Last Name:<br/>
            <input type="text" name="lname" placeholder="last name"/><br/>
            Gender:<br/>
            <input type="radio" name="gender"  value="Male" checked/>Male
            <input type="radio" name="gender"  value="Female" />Female <br/>
            Date of Birth:<br/>
            <input type="date" name="dob"/><br/>
            Email:<br/>
            <input type="email" name="email" placeholder="Email address"/><br/>
            <input type="submit" value="Submit"/>
        </form>
    </body>
</html>

<%@page contentType="text/html" pageEncoding="UTF-8"%>

<!DOCTYPE html">

<html>

<head>

<title>Getting all parameters in servlet</title>

</head>

<body>

<h1>Getting all parameters in servlet</h1>

First Name:<br/>

Middle Name:<br/>

Last Name:<br/>

Gender:<br/>

<input type="radio" name="gender" value="Male" checked/>Male

<input type="radio" name="gender" value="Female" />Female <br/>

Date of Birth:<br/>

Email:<br/>

</form>

</body>

</html>

AllSerlvet.java

package com.ebhor.servletparameters;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(name = "AllParameters", urlPatterns = {"/allparameters"})
public class AllParameters extends HttpServlet {

    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        out.println("<!DOCTYPE html>");
        out.println("<html>");
        out.println("<head>");
        out.println("<title>Servlet AllParameters</title>");
        out.println("</head>");
        out.println("<body>");
        try {
            Enumeration<String> parameterNames = request.getParameterNames();
            while (parameterNames.hasMoreElements()) {
                String parameterName = parameterNames.nextElement();
                String value = request.getParameter(parameterName);
                System.out.println("parameter name is " + parameterName);
                out.println("Parameter name is  <b>" + parameterName + "</b>  value is <b> " + value + "</b><br/>");
            }

            out.println("</body>");
            out.println("</html>");
        } finally {
            out.close();
        }
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }
}

package com.ebhor.servletparameters;

import java.io.IOException;

import java.io.PrintWriter;

import java.util.Enumeration;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

@WebServlet(name = "AllParameters", urlPatterns = {"/allparameters"})

public class AllParameters extends HttpServlet {

protected void processRequest(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setContentType("text/html;charset=UTF-8");

PrintWriter out = response.getWriter();

out.println("<!DOCTYPE html>");

out.println("<html>");

out.println("<head>");

out.println("<title>Servlet AllParameters</title>");

out.println("</head>");

out.println("<body>");

try {

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

while (parameterNames.hasMoreElements()) {

String parameterName = parameterNames.nextElement();

String value = request.getParameter(parameterName);

System.out.println("parameter name is " + parameterName);

out.println("Parameter name is <b>" + parameterName + "</b> value is <b> " + value + "</b><br/>");

}

out.println("</body>");

out.println("</html>");

} finally {

out.close();

}

@Override

protected void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

processRequest(request, response);

}

@Override

protected void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

processRequest(request, response);

}

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.ebhor</groupId>
    <artifactId>ServletParameters</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <name>ServletParameters</name>

    <properties>
        <endorsed.dir>${project.build.directory}/endorsed</endorsed.dir>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-web-api</artifactId>
            <version>6.0</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.3.2</version>
                <configuration>
                    <source>1.6</source>
                    <target>1.6</target>
                    <compilerArguments>
                        <endorseddirs>${endorsed.dir}</endorseddirs>
                    </compilerArguments>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.1.1</version>
                <configuration>
                    <failOnMissingWebXml>false</failOnMissingWebXml>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-dependency-plugin</artifactId>
                <version>2.1</version>
                <executions>
                    <execution>
                        <phase>validate</phase>
                        <goals>
                            <goal>copy</goal>
                        </goals>
                        <configuration>
                            <outputDirectory>${endorsed.dir}</outputDirectory>
                            <silent>true</silent>
                            <artifactItems>
                                <artifactItem>
                                    <groupId>javax</groupId>
                                    <artifactId>javaee-endorsed-api</artifactId>
                                    <version>6.0</version>
                                    <type>jar</type>
                                </artifactItem>
                            </artifactItems>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

<groupId>com.ebhor</groupId>

<artifactId>ServletParameters</artifactId>

<version>1.0-SNAPSHOT</version>

<name>ServletParameters</name>

<endorsed.dir>${project.build.directory}/endorsed</endorsed.dir>

<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

</properties>

<groupId>javax</groupId>

<artifactId>javaee-web-api</artifactId>

<scope>provided</scope>

</dependency>

</dependencies>

<build>

<groupId>org.apache.maven.plugins</groupId>

<artifactId>maven-compiler-plugin</artifactId>

<endorseddirs>${endorsed.dir}</endorseddirs>

</compilerArguments>

</configuration>

</plugin>

<groupId>org.apache.maven.plugins</groupId>

<artifactId>maven-war-plugin</artifactId>

<failOnMissingWebXml>false</failOnMissingWebXml>

</configuration>

</plugin>

<groupId>org.apache.maven.plugins</groupId>

<artifactId>maven-dependency-plugin</artifactId>

<phase>validate</phase>

<goals>

</goals>

<outputDirectory>${endorsed.dir}</outputDirectory>

<groupId>javax</groupId>

<artifactId>javaee-endorsed-api</artifactId>

</artifactItem>

</artifactItems>

</configuration>

</execution>

</executions>

</plugin>

</plugins>

</build>

</project>

Result:
1309_first

1309_seconf