Create BarCode in JSP-Servlet

<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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>LearnJSPServletWithRealApps</groupId>
    <artifactId>LearnJSPServletWithRealApps</artifactId>
    <packaging>war</packaging>
    <version>0.0.1-SNAPSHOT</version>
    <name>Learn JSP-Servlet with Real Apps</name>
    <url>http://maven.apache.org</url>
    <dependencies>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>javax.servlet.jsp.jstl</groupId>
            <artifactId>javax.servlet.jsp.jstl-api</artifactId>
            <version>1.2.1</version>
        </dependency>

        <dependency>
            <groupId>taglibs</groupId>
            <artifactId>standard</artifactId>
            <version>1.1.2</version>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>com.google.zxing</groupId>
            <artifactId>core</artifactId>
            <version>3.3.3</version>
        </dependency>

        <dependency>
            <groupId>com.google.zxing</groupId>
            <artifactId>javase</artifactId>
            <version>3.3.3</version>
        </dependency>

    </dependencies>
    <build>
        <finalName>LearnJSPServletWithRealApps</finalName>
    </build>
</project>

<!DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>
</web-app>

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1" isELIgnored="false"%>
<jsp:forward page="demo"></jsp:forward>

package com.demo.servlets;

import java.io.IOException;
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("/demo")
public class DemoServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public DemoServlet() {
        super();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.getRequestDispatcher("demo/index.jsp").forward(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String productId = request.getParameter("productId");
        request.setAttribute("productId", productId);
        request.getRequestDispatcher("demo/index.jsp").forward(request, response);
    }

}

package com.demo.servlets;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Hashtable;

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

import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.Writer;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.oned.Code128Writer;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;

@WebServlet("/barcode")
public class BarCodeServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public BarCodeServlet() {
        super();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String productId = request.getParameter("productId");
        response.setContentType("image/png");
        OutputStream outputStream = response.getOutputStream();
        outputStream.write(getBarCodeImage(productId, 400, 200));
        outputStream.flush();
        outputStream.close();
    }

    private byte[] getBarCodeImage(String text, int width, int height) {
        try {
            Hashtable<EncodeHintType, ErrorCorrectionLevel> hintMap = new Hashtable<EncodeHintType, ErrorCorrectionLevel>();
            hintMap.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.L);
            Writer writer = new Code128Writer();
            BitMatrix bitMatrix = writer.encode(text, BarcodeFormat.CODE_128, width, height);
            ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
            MatrixToImageWriter.writeToStream(bitMatrix, "png", byteArrayOutputStream);
            return byteArrayOutputStream.toByteArray();
        } catch (Exception e) {
            return null;
        }
    }

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

}

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1" isELIgnored="false"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
<title>BarCode</title>
</head>
<body>

    <h3>Create BarCode</h3>
    <form method="post" action="${pageContext.request.contextPath }/demo">
        <input type="text" name="productId" placeholder="Input product id" value="${productId}">
        <input type="submit" value="Generate">
        <c:if test="${productId != null }">
            <br><br>
            <img src="${pageContext.request.contextPath }/barcode?productId=${productId }" width="400" height="200">
        </c:if>
    </form>

</body>
</html>