Thread: Google Chart from database Servlet not working

Hi all I am trying to produce a google line chart with the following classes but its not producing anything so far .. I dont see why this code desnt work .. I am using eclipse indigo and tomcat 6 and I retrieve data values from a mysql table...

My database connection class :

package Graph;
import java.sql.DriverManager;
import java.sql.SQLException;
 
import com.mysql.jdbc.Connection;
 
public final class DatabaseConnection {
 
    private static final String HOST = "localhost:3306",
            DATABASE = "database name",
            USERNAME = "username",
            PASSWORD = "password";
 
    private Connection connect;
 
    public static final DatabaseConnection _instance = new DatabaseConnection();
 
    public DatabaseConnection() {
        try {
            Class clazz = Class.forName("com.mysql.jdbc.Driver");
            connect();
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
 
    public Connection getConnection() throws SQLException {
        if(!connect.isValid(100))
            connect();
    	return connect;
    }
 
    public void connect() throws SQLException {
        connect = (Connection) DriverManager.getConnection("jdbc:mysql://" + HOST
                + "/" + DATABASE, USERNAME, PASSWORD);
    }
}

my Chart Servlet that should basically form a google link that produces an image ( the chart) .. and no image is shown. code below:

package Graph;
 
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;
 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
import com.mysql.jdbc.Connection;
import com.mysql.jdbc.ResultSetMetaData;
import com.mysql.jdbc.Statement;
 
/**
 * Servlet implementation class Graph
 */
public class Graph extends HttpServlet {
	private static final long serialVersionUID = 1L;
	private static final String DatabaseConnection = null;
 
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Graph() {
        super();
        // TODO Auto-generated constructor stub
    }
 
	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 
		        OutputStreamWriter writer = new OutputStreamWriter(response.getOutputStream());
		        System.out.println("SensorGraph");
 
		        response.setContentType("text/html");
		        PrintWriter out = response.getWriter();
 
		        DatabaseConnection db_connection =  new DatabaseConnection()._instance;
		        Connection connection = null;
		        try {
		            connection = db_connection.getConnection();
		        } catch (SQLException e) {
		            e.printStackTrace();
		        }
		        Statement statement;
		        ResultSet resultSet;
		        try {
		            statement = (Statement) connection.createStatement();
		            resultSet = statement.executeQuery("select * from Sensor_Entries order by EntryTime asc limit 5)");
		            String values = "";
		            while(resultSet.next()) {
		                String value = resultSet.getString("EntryValue");
		                values += (value) + ",";
		            }
		            System.out.println(values);
		            values = values.substring(0, values.length()-1);
 
 
		            String image = "http://chart.apis.google.com/chart?" +
		                    "chxr=0,0,1000" +
		                    "&chxs=0,676767,12.167,-0.5,l,676767" +
		                    "&chxt=y" +
		                    "&chs=300x225" +
		                    "&cht=ls" +
		                    "&chco=3D7930" +
		                    "&chds=0,1000" +
		                    "&chd=t:" + values+  \\ magic line - gives the values to the link 
		                    "&chg=14.3,-1,1,1" +
		                    "&chls=2,4,0" +
		                    "&chma=0,6%7C3" +
		                    "&chm=B,C5D4B5BB,0,0,0" +
		                    "&chtt=Sensor+Values" +
		                    "&chts=F00D0D,14.5";
		            if(request.getParameter("img") != null)
		                out.write("<img src=\"" + image + "\" />");
 
		            statement = (Statement) connection.createStatement();
		            resultSet = statement.executeQuery("select * from Sensors join " +
		                    "(select * from Sensor_Entries order by EntryTime desc) as Sensor_Entries on " +
		                    "(Sensors.SensorID=Sensor_Entries.SensorID) where Sensors.SensorID='" + id + "' " +
		                    "group by Sensors.SensorID;");
 
		            ResultSetMetaData resultSetMetaData = (ResultSetMetaData) resultSet.getMetaData();
		            if(resultSet.next()) {
		                writer.write("<table>");
		                for(int i = 1; i < resultSetMetaData.getColumnCount() + 1; i++) {
		                    String value = "";
		                    int type = resultSetMetaData.getColumnType(i);
		                    if(type == Types.INTEGER || type == Types.TINYINT) {
		                        value = "" + resultSet.getInt(i);
		                    } else if(type == Types.VARCHAR) {
		                        value = resultSet.getString(i);
		                    } else if(type == Types.TIMESTAMP) {
		                        value = resultSet.getTimestamp(i).toString();
		                    } else if(type == Types.DOUBLE) {
		                        value = "" + resultSet.getDouble(i);
		                    }
		                    writer.write("<tr>" +
		                            "<td>" + resultSetMetaData.getColumnName(i) + "</td>" +
		                            "<td>" + value + "</td>" +
		                            "</tr>");
		                }
		                writer.write("</table></center>");
		            }
		            else
		                out.write(image);
		            out.flush();
		            out.close();
		        } catch (SQLException ignored) { ignored.printStackTrace();  }
		    }
 
	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
}
}