Tapestry5HowToCreateASimpleGraphComponent

<t:chart width="200" height="150" context="chart1" popup="popupSize"/>
<t:chart width="400" height="300" context="chart2" popup="popupSize"/>

public String[] getChart1(){
    return new String[]{"aa","22","bb","5"};
}

public String[] getChart2(){
    return new String[]{"aa","29","bb","30","cc","10"};
}
public int[] getpopupSize(){
    return new int[]{800,600};
}

	<dependency>
		<groupId>jfree</groupId>
		<artifactId>jfreechart</artifactId>
		<version>1.0.5</version>
	</dependency>

import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;

import org.apache.tapestry.ComponentResources;
import org.apache.tapestry.Link;
import org.apache.tapestry.MarkupWriter;
import org.apache.tapestry.StreamResponse;
import org.apache.tapestry.annotations.Inject;
import org.apache.tapestry.annotations.Parameter;
import org.apache.tapestry.dom.Element;
import org.apache.tapestry.ioc.services.TypeCoercer;
import org.apache.tapestry.services.Response;
import org.jfree.chart.ChartUtilities;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PiePlot3D;
import org.jfree.data.DefaultKeyedValues;
import org.jfree.data.general.DefaultPieDataset;
import org.jfree.data.general.PieDataset;

public class Chart{
    
    /**list(array) of paired values(label & value): [String,Number,String,Number,...]*/
    @Parameter(required=true)
    private List<Object> _context;

    @Parameter(required=true)
    private int _width;

    @Parameter(required=true)
    private int _height;

    /** width and height of the popup chart, if omitted, javascript for popup chart is omitted from output*/
    @Parameter
    private int[] _popup;
    
    @Inject
    private ComponentResources _resources;

    @Inject
    private TypeCoercer _coercer;
    
    @SuppressWarnings("unchecked")
    void beginRender(MarkupWriter writer)
    {
        //add width and height to begining of parameters
        Object[] contextArray = _context == null ? new Object[0] : _context.toArray();
        Object[] params = new Object[contextArray.length+2];
        System.arraycopy(contextArray, 0, params, 2, contextArray.length);
        params[0] = new Integer(_width);
        params[1] = new Integer(_height);
        
        //generate action link
        Link link = _resources.createActionLink("chart", false, params);
        Element img = writer.element("img", "src", link);
        
        //add javascript for popup
        if(_popup != null && _popup.length > 1){
            params[0] = _popup[0];
            params[1] = _popup[1];
            link = _resources.createActionLink("chart", false, params);
            img.attribute("onclick", "window.open('"+link+"','_blank','width="+(_popup[0]+24)+", height="+(_popup[1]+24)+"')");
            img.attribute("style", "cursor:pointer");
        }

        _resources.renderInformalParameters(writer);
    }

    void afterRender(MarkupWriter writer)
    {
        writer.end();
    }

    public StreamResponse onChart(final int width, final int height, Object ...rest){
        DefaultKeyedValues values = new DefaultKeyedValues();
        for (int i = 3; i < rest.length; i+=2){
            values.addValue(rest[i-1].toString(), _coercer.coerce(rest[i], Number.class));
        }        
        PieDataset pieDataset = new DefaultPieDataset(values);

        PiePlot3D plot = new PiePlot3D(pieDataset);
        plot.setForegroundAlpha(0.5f);
        plot.setDepthFactor(0.1);
        plot.setCircular(true);
        
        final JFreeChart chart = new JFreeChart(plot);
        
        return new StreamResponse(){
            public String getContentType(){
                return "image/jpeg";
            }
            public InputStream getStream() throws IOException {
                BufferedImage image  = chart.createBufferedImage(width, height);
                ByteArrayOutputStream byteArray = new ByteArrayOutputStream() ;
                ChartUtilities.writeBufferedImageAsJPEG(byteArray, image) ;
                return new ByteArrayInputStream(byteArray.toByteArray());
            }
            public void prepareResponse(Response response){}
        };
    }
}