Trying to understand

[gchrt]

Here is the servlet:

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package com.dunlopconsult.clayforeman.servlets;

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

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

import java.awt.Font;

import org.jfree.chart.JFreeChart;
import org.jfree.chart.ChartUtilities;
import org.jfree.chart.axis.CategoryAxis;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.axis.ValueAxis;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.renderer.CategoryItemRenderer;
import org.jfree.chart.renderer.StatisticalBarRenderer;
import org.jfree.data.DefaultCategoryDataset;
import org.jfree.data.statistics.DefaultStatisticalCategoryDataset;
import org.jfree.data.statistics.StatisticalCategoryDataset;
import org.jfree.ui.ApplicationFrame;
import org.jfree.ui.RefineryUtilities;

public class CF_ChartGeneratorServlet extends HttpServlet {
    
    /**
     * Default constructor.
     */
    public CF_ChartGeneratorServlet() {
        // nothing required
    }    

    /**
     * Process a GET request.
     *
     * @param request  the request.
     * @param response  the response.
     *
     * @throws ServletException if there is a servlet related problem.
     * @throws IOException if there is an I/O problem.
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {

        response.setContentType("image/png");
        OutputStream out = response.getOutputStream();
        StatisticalCategoryDataset dataset = createDataset();

        CategoryAxis xAxis = new CategoryAxis("Type");
        xAxis.setLowerMargin(0.01d); // percentage of space before first bar
        xAxis.setUpperMargin(0.01d); // percentage of space after last bar
        xAxis.setCategoryMargin(0.05d); // percentage of space between categories
        ValueAxis yAxis = new NumberAxis("Value");

        // define the plot
        CategoryItemRenderer renderer = new StatisticalBarRenderer();
        CategoryPlot plot = new CategoryPlot(dataset, xAxis, yAxis, renderer);

        JFreeChart chart = new JFreeChart("Statistical Bar Chart Demo",
                                          new Font("Helvetica", Font.BOLD, 14),
                                          plot,
                                          true);
        ChartUtilities.writeChartAsPNG(out, chart, 600, 500);
        out.close();
    }

    /**
     * Creates a sample dataset.
     *
     * @return The dataset.
     */
    private StatisticalCategoryDataset createDataset() {

        final DefaultStatisticalCategoryDataset result = new DefaultStatisticalCategoryDataset();

        result.add(32.5, 17.9, "Series 1", "Type 1");
        result.add(27.8, 11.4, "Series 1", "Type 2");
        result.add(29.3, 14.4, "Series 1", "Type 3");
        result.add(37.9, 10.3, "Series 1", "Type 4");

        result.add(22.9,  7.9, "Series 2", "Type 1");
        result.add(21.8, 18.4, "Series 2", "Type 2");
        result.add(19.3, 12.4, "Series 2", "Type 3");
        result.add(30.3, 20.7, "Series 2", "Type 4");

        result.add(12.5, 10.9, "Series 3", "Type 1");
        result.add(24.8,  7.4, "Series 3", "Type 2");
        result.add(19.3, 13.4, "Series 3", "Type 3");
        result.add(17.1, 10.6, "Series 3", "Type 4");

        return result;

    }
  

Here is the jsp call:

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img src="http://localhost:8081/com/dunlopconsult/clayforeman/servlets/CF_ChartGeneratorServlet" /

I am not getting a chart image.

Any ideas?

[richard_atkinson]

Do you have a servlet definition and mapping setup in your web.xml file?

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    <servlet>
        <servlet-name>DisplayChart</servlet-name>
        <servlet-class>org.jfree.chart.servlet.DisplayChart</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>DisplayChart</servlet-name>
        <url-pattern>/servlet/DisplayChart</url-pattern>
     </servlet-mapping>

Then you can reference your servlet using

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http://localhost:8081/servlet/DisplayChart

Check out the sample WAR file to see a complete example.

Regards,
Richard...

[gchrt]

Richard,

Thank you for replying.

Please excuse my inexperience in both jfreeChart and java.

In reference to your war file, when clicking on it I get a document of code.
Is this saved then used somehow?

I have my web.xml file mapped for DisplayChart.
I tried referencing the servlet as suggested but still no image.

I am using NetBeans IDE and with a breakpoint in the chart building servlet the process never gets further than the default constructor.

again thank you for taking the time to help me solve my dilemma. It has been a frustrating few days.

[richard_atkinson]

Try right clicking on the WAR file link and clicking "Save target as" or whatever looks a likely option in your browser. In a default Tomcat installation you can drop it in the webapps directory and then start Tomcat and it will deploy automatically to /jfreechart-sample.

Check you servlet engine log files for additional errors that might be coming from your servlet.

Regards,
Richard...

[joelwyland]

I have my web.xml file mapped for DisplayChart.
I tried referencing the servlet as suggested but still no image.

Can you post the section of your web.xml that configures the DisplayChart servlet?

[gchrt]

Here are the two sections in my web.xml file referring to DisplayChart:

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  <servlet>
  <servlet-name>DisplayChart</servlet-name>
  <servlet-class>org.jfree.chart.servlet.DisplayChart</servlet-class>
  </servlet>
  
  <servlet-mapping>
  <servlet-name>DisplayChart</servlet-name>
  <url-pattern>/servlet/org/jfree/chart/servlet/DisplayChart</url-pattern>
  </servlet-mapping>

[joelwyland]

Here are the two sections in my web.xml file referring to DisplayChart:

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  <servlet>
  <servlet-name>DisplayChart</servlet-name>
  <servlet-class>org.jfree.chart.servlet.DisplayChart</servlet-class>
  </servlet>
  
  <servlet-mapping>
  <servlet-name>DisplayChart</servlet-name>
  <url-pattern>/servlet/org/jfree/chart/servlet/DisplayChart</url-pattern>
  </servlet-mapping>

In your first post, you said the JSP was trying to load an image from:
img src="http://localhost:8081/com/dunlopconsult ... torServlet" /

Which means that you need to have a servlet-mapping that references /com/dunlopconsult/clayforeman/servlets/CF_ChartGeneratorServlet

Like so:

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  <servlet>
  <servlet-name>DisplayChart</servlet-name>
  <servlet-class>com.dunlopconsult.clayforeman.servlets.CF_ChartGeneratorServlet</servlet-class>
  </servlet>
  
  <servlet-mapping>
  <servlet-name>DisplayChart</servlet-name>
  <url-pattern>/com/dunlopconsult/clayforeman/servlets/CF_ChartGeneratorServlet</url-pattern>
  </servlet-mapping>

Kenny[/code]

[gchrt]

Thank you for taking the time to assist me in this endeavor.

I followed your advise and remapped my web.xml but to no avail.

Again the servlet is not being run when called upon.

My initial call to the chart building servlet is through another servlet I am using to parse user entered data. Could this be the culprit:

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CF_ChartGeneratorServlet chart = new CF_ChartGeneratorServlet();

Again I really appreciate any insight I can get.

[gchrt]

I routed the call to the chart builder servlet through my main controller forwarding the req/resp.
Now I get a run down through the servlet to:

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JFreeChart chart = new JFreeChart("", new Font("Helvetica" Font.BOLD, 14), plot, true);

Where I now get a HTTP Status 500 - Internal Server Error:

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java.lang.ClassCastException
at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:246)

Something in JFreeChart that I have sent it would cause this?

[tonghz]

Can anyone tell me what use of the bool urls param? thx in advance.

final JFreeChart chart = ChartFactory.createBarChart3D(
"3D Bar Chart Demo", // chart title
"Category", // domain axis label
"Value", // range axis label
dataset, // data
PlotOrientation.VERTICAL, // orientation
true, // include legend
true, // tooltips
false // urls
);

[angel]

Can anyone tell me what use of the bool urls param? thx in advance.

final JFreeChart chart = ChartFactory.createBarChart3D(
"3D Bar Chart Demo", // chart title
"Category", // domain axis label
"Value", // range axis label
dataset, // data
PlotOrientation.VERTICAL, // orientation
true, // include legend
true, // tooltips
false // urls
);

http://www.jfree.org/jfreechart/javadoc ... BarChart3D