ใช้งาน JFreeChart บน Servlet @see http://devsharing.com/jfreechart-on-servlet-example/

DevChart.createPieChart.java

private JFreeChart createPieChart() {

	DefaultPieDataset dataset = new DefaultPieDataset();
	dataset.setValue("ส้มตำ", 34);
	dataset.setValue("กระเพาะไก่", 87);
	dataset.setValue("น้ำตกหมู", 72);
	dataset.setValue("ข้าวต้มปลา", 52);
	dataset.setValue("กุ้งเผา", 61);

	JFreeChart chart = ChartFactory.createPieChart("อาหารที่ชื่นชอบ", dataset,
			true, true, false);
	return chart;
}

DevChart.doPost.java

OutputStream out = response.getOutputStream();

JFreeChart pieChart = createPieChart();
response.setContentType("image/png");
ChartUtilities.writeChartAsPNG(out, pieChart, 640, 480);

out.close();

DevChart.java

package com.devsharing.jfreechart;

import java.io.IOException;
import java.io.OutputStream;

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 org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartUtilities;
import org.jfree.chart.JFreeChart;
import org.jfree.data.general.DefaultPieDataset;

@WebServlet(description = "Chart Demo", urlPatterns = { "/chartDemo" })
public class DevChart extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request,
        HttpServletResponse response) throws ServletException, IOException {
		
        OutputStream out = response.getOutputStream();

        JFreeChart pieChart = createPieChart();
        response.setContentType("image/png");
        ChartUtilities.writeChartAsPNG(out, pieChart, 640, 480);
        out.close();
    }

    private JFreeChart createPieChart() {

        DefaultPieDataset dataset = new DefaultPieDataset();
        dataset.setValue("ส้มตำ", 34);
        dataset.setValue("กระเพาะไก่", 87);
        dataset.setValue("น้ำตกหมู", 72);
        dataset.setValue("ข้าวต้มปลา", 52);
        dataset.setValue("กุ้งเผา", 61);
        JFreeChart chart = ChartFactory.createPieChart("อาหารที่ชื่นชอบ",
            dataset, true, true, false);
        return chart;
    }
}

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/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.devsharing.jfreechart</groupId>
  <artifactId>DevChart</artifactId>
  <packaging>war</packaging>
  <version>0.0.1-SNAPSHOT</version>
  <name>DevChart Maven Webapp</name>
  <url>http://maven.apache.org</url>
  
    <properties>
    <servlet-api-version>2.5</servlet-api-version>
    <jfreechart-version>1.0.13</jfreechart-version>
    <jcommon-version>1.0.16</jcommon-version>
  </properties>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    
        <!-- Servlet API -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>servlet-api</artifactId>
      <version>${servlet-api-version}</version>
    </dependency>
    
        <!-- JFreeChart -->
    <dependency>
      <groupId>jfree</groupId>
      <artifactId>jfreechart</artifactId>
      <version>${jfreechart-version}</version>
    </dependency>

    <!-- JCommon -->
    <dependency>
      <groupId>jfree</groupId>
      <artifactId>jcommon</artifactId>
      <version>${jcommon-version}</version>
    </dependency>
  </dependencies>
  <build>
    <finalName>DevChart</finalName>
  </build>
</project>

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_3_0.xsd"
  id="WebApp_ID" version="3.0">
  <display-name>DevChart</display-name>
</web-app>