Plot Curve in Servlet using Graphics2D

[Apple Khoa]

Hi all,

I am trying to plot a quadratic curve in a servlet which will display the output as a pdf file. I am not sure if Graphics2D in java.awt.Graphics2D can be used in servlet, so i gave it a try. I face some problems as described below:

My servlet code:

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.lowagie.text.Chunk;
import com.lowagie.text.Document;
import com.lowagie.text.Font;
import com.lowagie.text.Paragraph;
import com.lowagie.text.pdf.PdfWriter;

import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.QuadCurve2D;

public class Curve extends HttpServlet {     
   
	protected void doGet(HttpServletRequest request, HttpServletResponse response) 
	throws ServletException, IOException {		
		
		response.setContentType("application/pdf");
		Document doc = new Document();
		response.setHeader("Content-disposition", "inline; filename=\"Worksheet.pdf\"");
		try{
		PdfWriter pdf = PdfWriter.getInstance(doc,response.getOutputStream());
		doc.open();
					
		public void paint(Graphics g) 
		{
		    Graphics2D g2d = (Graphics2D) g;

		    QuadCurve2D quadcurve = new QuadCurve2D.Float(50, 300, 320, 300, 350, 400);
		    g2d.draw(quadcurve);
		    doc.add(new Paragraph(quadcurve));
		}			

		doc.close ();
		}catch(Exception e){
	    System.out.println(e);} // catch error 		
	}
}

Error shown by Eclipse:

public void paint(Graphics g)

Suggestion by Eclipse: "Void is an invalid type for the variable paint" (This wasn't a problem if it is a normal Java file, not a servlet)

Error shown by Eclipse:

doc.add(new Paragraph(quadcurve));

Suggestions by Eclipse:
1. "Remove argument to match Paragraph();" > Doing so will remove the quadcurve
2. "Change type of quadcurve to float" > But quadcurve is not a float in the first place.

Any help to resolve this issue will be greatly appreciated.

Thanks in advance.

[Darryl Burke]

Apple Khoa wrote:

:
:
public class Curve extends HttpServlet {     
   
	protected void doGet(HttpServletRequest request, HttpServletResponse response) 
	throws ServletException, IOException {		
:
:
		public void paint(Graphics g) 
		{
:
:
		}			
:
:
	}
}

You're trying to create a method inside another one. You can't do that.

[Ulf Dittmer]

You can't have a method inside of a method.

I'm not quite sure what you're trying to do, but I very much doubt that it's going to work. The Servlet API has no provisions for a "paint" method.

[Apple Khoa]

Ulf Dittmer wrote:You can't have a method inside of a method.

I'm not quite sure what you're trying to do, but I very much doubt that it's going to work. The Servlet API has no provisions for a "paint" method.

I am trying to draw Quadratic curves with my Servlet which will then output the curve in pdf format. I thought I can achieve that using Graphics2D in the java.awt.Graphics2D. So, can I say that Graphics2D is not supported in servlet?

[Darryl Burke]

You can construct a BufferedImage, obtain its Graphics2D and draw to it.

You can then save the image or write it to a stream using ImageIO.