JAVA 生成验证码

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

import com.google.code.kaptcha.Constants;

@Controller
public class CaptchaController {

@RequestMapping("/kaptcha")
public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
	response.setDateHeader("Expires", 0);
	response.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");
	response.addHeader("Cache-Control", "post-check=0, pre-check=0");
	response.setHeader("Pragma", "no-cache");
	response.setContentType("image/jpeg");
	HttpSession session = request.getSession();
	
	BufferedImage bufImage = new BufferedImage(80, 30, BufferedImage.TYPE_3BYTE_BGR); // 创建BufferedImage对象
	Graphics gra = bufImage.getGraphics(); // 使用BufferedImage对象得到Graphics对象
	Random ran = new Random(); // 随机数对象
	gra.setColor(Color.white); // 设置画布背景色
	gra.setFont(new Font("Times New Roman", Font.ITALIC, 20));// 设置字体
	gra.fillRect(0, 0, 80, 30); // 此部为绘制一个矩形，其中x,y坐标都是从0开始，宽度为80，高度为30
	String vliCode = "";
	while (vliCode.length() < 4) {
		gra.setColor(new Color(0, 68, 141)); // 随机得到颜色用于绘制内容
		int tmp;
		// the style of the code
		switch (ran.nextInt(3)) {
		case 0:
			tmp = ran.nextInt(10); // 得到数字0-9
			break;
		case 1:
			tmp = ran.nextInt(10); // 得到数字0-9
			break;
		default:
			tmp = ran.nextInt(10); // 得到数字0-9
			break;
		}
		gra.drawString(tmp + "", 10 + vliCode.length() * 15, 20); // 此步为在x坐标为（10+vliCode.length()*20）y坐标为20的地方绘制内容为tmp的字符图。
		vliCode += tmp;
	}
	// 绘制干扰线
	gra.setColor(new Color(0, 68, 141)); // 设置干扰线的颜色
	gra.drawLine(0, 15, 100, 5); // 设置干扰线的坐标
	
	//设置超时时间
	session.setMaxInactiveInterval(60*10);
	session.setAttribute(Constants.KAPTCHA_SESSION_KEY, vliCode);
	ServletOutputStream out = response.getOutputStream();
	ImageIO.write(bufImage, "jpg", out);
	try {
		out.flush();
	} finally {
		out.close();
	}
	return null;
}
}