JSP/Servlet: 一个动态产生图片的例子

• ImageShower.java

package onlyfun.caterpillar;
 
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
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 com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
 
public class ImageShower extends HttpServlet {
    public void doGet(HttpServletRequest req, 
                      HttpServletResponse res) 
                      throws ServletException, IOException {
        res.setContentType("image/jpeg");
        
        BufferedImage bufferedImage = 
                 new BufferedImage(300, 200, 
                         BufferedImage.TYPE_INT_RGB);
        Graphics g = bufferedImage.getGraphics();
        
        g.setColor(Color.white);
        g.setFont(new Font("Arial Black", 
                          Font.ITALIC | Font.BOLD, 20));
        g.drawString("caterpillar.onlyfun.net", 20, 20);
        g.setColor(Color.red);
        g.fillOval(40, 40, 20, 20);
        g.setColor(Color.green);
        g.fillRect(80, 80, 50, 50);
        
        OutputStream out = res.getOutputStream();
        JPEGImageEncoder encoder = 
                           JPEGCodec.createJPEGEncoder(out); 
        encoder.encode(bufferedImage);
        out.close();
    }
}