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JSP/Servlet: 一个动态产生图片的例子

要动态产生图片其实很简单，直接看一个Servlet实作的例子：

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();
}
} 

图片的成果如下：