Problems with writing image on server side

Hello everyone!
Recently, I'am working on a JSP project, in that project, I'm responsible for building a .png file and saved it on a hard disk with JFreeChart on the server side(the server is Tomcat 5.0.28),and then insert the .png file into a jsp page using a customized tag lib, in effect, that tag only return the absolute path of that .png file. Here is the complete code:

package com.amoysa.tag;
 
import javax.servlet.jsp.tagext.*;
import java.io.*;
import org.jfree.data.xy.*;
import org.jfree.chart.*;
import org.jfree.chart.plot.*;
 
import java.awt.*;
 
public class ChartGenerator extends TagSupport{
private String temppath = new File(".").getAbsolutePath();
private String path = temppath.substring(0,temppath.length()-2);
private String chartPath = path + "\\chart.png";
private static XYSeriesCollection getDataset(){
XYSeriesCollection dataSet = new XYSeriesCollection();
XYSeries series1 = new XYSeries("first");
XYSeries series2 = new XYSeries("second");
XYSeries series3 = new XYSeries("third");
series1.add(1.0, 1.0);
series1.add(2.0, 4.0);
series1.add(3.0, 3.0);
series1.add(4.0, 5.0);
series1.add(5.0, 5.0);
series1.add(6.0, 7.0);
series1.add(7.0, 7.0);
series1.add(8.0, 8.0);

series2.add(1.0, 5.0);
series2.add(2.0, 7.0);
series2.add(3.0, 6.0);
series2.add(4.0, 8.0);
series2.add(5.0, 4.0);
series2.add(6.0, 4.0);
series2.add(7.0, 2.0);
series2.add(8.0, 1.0);

series3.add(3.0, 4.0);
series3.add(4.0, 3.0);
series3.add(5.0, 2.0);
series3.add(6.0, 3.0);
series3.add(7.0, 6.0);
series3.add(8.0, 3.0);
series3.add(9.0, 4.0);
series3.add(10.0, 3.0);
dataSet.addSeries(series1);
dataSet.addSeries(series2);
dataSet.addSeries(series3);
return dataSet;
}
public int doStartTag(){
JFreeChart chart = ChartFactory.createXYLineChart(
"Line Chart Demo 2",
"X",
"Y",
getDataset(),
PlotOrientation.VERTICAL,
true,
true,
false
);
chart.setBackgroundPaint(Color.CYAN);
XYPlot plot = chart.getXYPlot();
plot.setBackgroundPaint(Color.lightGray);
plot.setDomainGridlinePaint(Color.WHITE);
plot.setRangeGridlinePaint(Color.WHITE);
FileOutputStream fos_png = null;
try {
fos_png = new FileOutputStream(chartPath);
ChartUtilities.writeChartAsPNG(fos_png,chart,400,300,null);
pageContext.getOut().print(chartPath);
}catch(FileNotFoundException notFoundEx){}
catch(IOException ioex){}
return SKIP_BODY;
}
}

some fraction of my jsp file is:
but when I run the application, only me can see the image(since the Tomcat is installed on my computer), the image always stored under the {tomcat_home}/bin dir, rather than the com.amoysa.tag package.
My question is how can I solve this problem, let others see the png image.

The reason that all png file created under bin directory is caused by your code:
private String temppath = new File(".").getAbsolutePath();private String path = temppath.substring(0,temppath.length()-2);private String chartPath = path + "\\chart.png";

You can use the member 'pageContext' in TagSupport, then get ServletContext , call 'getRealPath' and change the root directory of your png under your web application's directory.