codeservlet.java

java学习的必要的资料,servlet的说明很好

package com.estore.struts.utils;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/*
 * 产生图片验证码。
 * 
 */
public class CodeServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("image/png");

		String code = genCode();

		request.getSession().setAttribute("code", code);

		BufferedImage image = new BufferedImage(80, 30, BufferedImage.TYPE_4BYTE_ABGR);
		Graphics2D g = (Graphics2D) image.getGraphics();
		
		g.setColor(new Color(237, 189, 0));
		g.drawLine(0, 0, 80, 30);
		
		g.setColor(new Color(160, 139, 57));
		Font f = g.getFont();
		
		g.setFont(new Font(f.getFamily(), f.getStyle(), 20));
		g.drawString(code, 10, 20);

		OutputStream out = response.getOutputStream();

		ImageIO.write(image, "png", out);

		out.close();

	}

	private String genCode() {
		Random random = new Random();
		StringBuilder buf = new StringBuilder();
		buf.append((char) ('A' + random.nextInt(26)));
		buf.append((char) ('A' + random.nextInt(26)));
		buf.append((char) ('A' + random.nextInt(26)));
		buf.append((char) ('A' + random.nextInt(26)));
		return buf.toString();
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}
}