Set JFreeChart data from database

by Hamid Reza Fahimi Madjd @ Jan 15, 2008

A couple of days ago I needed to generate some charts using Java so I searched for a library which could do it. Soon I found JFreeChart library and downloaded it from here. But I was surprised when I saw the user guide wasn't free! Therefore I decided to write this post and describe how to obtain JFreeChart data from database (I'll use mysql database).

At first I copied jcommon-1.0.12.jar, jfreechart-1.0.9.jar and mysql-connector-java-5.0.7-bin.jar files to /WEB-INF/lib directory then I created a table in the database and filled it with below data:

type             count
----------------------
invoice_detail    3273
----------------------
object_status     2819
----------------------
service_sales_... 1540
----------------------
call_function     1183
----------------------
contact           904
----------------------
invoice           775
----------------------
payment           596

Now I create DatabaseChart servlet for connecting to database and generating my chart

import org.jfree.data.jdbc.JDBCPieDataset;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartUtilities;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
import java.io.IOException;
import java.io.OutputStream;
import java.sql.SQLException;
import java.sql.DriverManager;
import java.sql.Connection;

public class DatabaseChart extends HttpServlet {

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

  public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    Connection connection = null;
    try {
      Class.forName("com.mysql.jdbc.Driver").newInstance();
      try {
        connection = DriverManager.getConnection("jdbc:mysql://localhost/my_db?user=my_un&password=my_pass&useUnicode=true&characterEncoding=utf-8");
      } catch (SQLException e) {
        e.printStackTrace();
      }
    } 
    catch (InstantiationException e) {
      e.printStackTrace();
    } 
    catch (IllegalAccessException e) {
      e.printStackTrace();
    } 
    catch (ClassNotFoundException e) {
      e.printStackTrace();
    }

    JDBCPieDataset dataset = new JDBCPieDataset(connection);
    try {
      dataset.executeQuery("Select `type`, `count` From my_table order by count desc");
      JFreeChart chart = ChartFactory.createPieChart("Pie Chart", dataset, true, true, false);
      if (chart != null) {
        response.setContentType("image/png");
        OutputStream out = response.getOutputStream();
        ChartUtilities.writeChartAsPNG(out, chart, 450, 400);
      }
    } 
    catch (SQLException e) {
      e.printStackTrace();
    }
    try {
      if(connection != null){connection.close();} 
    }
    catch (SQLException e) {e.printStackTrace();}
  }

}

at the end I add the servlet information to web.xml file

<servlet>
<servlet-name>generate_chart</servlet-name>
<servlet-class>DatabaseChart</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>generate_chart</servlet-name>
<url-pattern>/generate_chart</url-pattern>
</servlet-mapping>

now if you run the project you will get a chart like this

java, jfreechart