struts2+jfreechart生成热点图片的问题

<include file="struts-jfreechart.xml" />

<!doctype struts public
    "-//apache software foundation//dtd struts configuration 2.0//en"
    "http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
    <package name="jfreechartdemonstration" extends="struts-default">
        <result-types>
            <result-type name="chart" class="org.apache.struts2.dispatcher.chartresult"></result-type>
        </result-types>
        <action name="jfreechartaction" class="com.coraise.action.jfreechartaction">
            <result type="chart"> 
                   <param name="width">400</param>
                   <param name="height">300</param>
            </result>
        </action>
    </package>
</struts>

import com.opensymphony.xwork2.actioncontext;
import com.opensymphony.xwork2.actioninvocation;
import com.opensymphony.xwork2.result;
import com.opensymphony.xwork2.util.valuestack;
import java.io.outputstream;
import java.io.printwriter;

import javax.servlet.http.httpservletresponse;
import org.apache.struts2.servletactioncontext;
import org.jfree.chart.chartrenderinginfo;
import org.jfree.chart.chartutilities;
import org.jfree.chart.jfreechart;
import org.jfree.chart.entity.standardentitycollection;
import org.jfree.chart.servlet.servletutilities;

public class chartresult
    implements result
{

    public chartresult（)
    {
        chartset = false;
    }

    public chartresult（jfreechart chart, int height, int width)
    {
        chartset = false;
        setchart（chart);
        this.height = height;
        this.width = width;
    }

    public chartresult setchart（jfreechart chart)
    {
        this.chart = chart;
        chartset = true;
        return this;
    }

    public chartresult setheight（int height)
    {
        this.height = height;
        return this;
    }

    public chartresult setwidth（int width)
    {
        this.width = width;
        return this;
    }

    public void ＥＸＥＣute（actioninvocation invocation)
        throws exception
    {
        jfreechart chart = null;
        if（chartset)
            chart = this.chart;
        else
            chart = （jfreechart)invocation.getstack（).findvalue（"chart");
        if（chart == null)
        {
            throw new nullpointerexception（"no chart found");
        } else
        {
            httpservletresponse response = servletactioncontext.getresponse（);
            outputstream os = response.getoutputstream（);
            chartutilities.writechartaspng（os, chart, width, height);
            //以下为个人加的代码
            standardentitycollection entitycollection = new standardentitycollection（); 
            chartrenderinginfo info = new chartrenderinginfo（entitycollection);
            printwriter pw = new printwriter（os);
            chartutilities.writeimagemap（pw,"map0", info,false);
            //以上为个人加的代码
            os.flush（);
            return;
        }
    }

    private static final long serialversionuid = 0xa6017f6fda50aa4cl;
    jfreechart chart;
    boolean chartset;
    private int height;
    private int width;
}

import java.awt.*;

import org.jfree.chart.chartfactory;
import org.jfree.chart.chartrenderinginfo;
import org.jfree.chart.jfreechart;
import org.jfree.chart.entity.standardentitycollection;
import org.jfree.chart.labels.standardpietooltipgenerator;
import org.jfree.chart.plot.pieplot;
import org.jfree.chart.title.legendtitle;
import org.jfree.chart.urls.standardpieurlgenerator;
import org.jfree.data.general.defaultpiedataset;
import com.opensymphony.xwork2.actionsupport;

public class jfreechartaction extends actionsupport{
    private static final long serialversionuid = 5752180822913527064l;

    private jfreechart chart;
    
    private defaultpiedataset getdata（) {
        defaultpiedataset data = new defaultpiedataset（);
        data.setvalue（"java", new double（43.2));
        data.setvalue（"visual basic", new double（1.0));
        data.setvalue（"c/c++", new double（17.5));
        data.setvalue（"tangjun", new double（60.0));
        return data;
    }
    
    @override
    public string ＥＸＥＣute（) throws exception {
        return success;
    }

    public jfreechart getchart（) {
        chart = chartfactory.createpiechart（"",getdata（),true,true,true);
        legendtitle legend = chart.getlegend（0);
        legend.setitemfont（new font（"宋体", font.bold, 13));
        pieplot plot = （pieplot) chart.getplot（);
        plot.setlabelfont（new font（"隶书", font.bold, 26));
        plot.seturlgenerator（new standardpieurlgenerator（"index.jsp"));
        plot.settooltipgenerator（new standardpietooltipgenerator（));
        return chart;
    }
}