Spring Mvc添加验证码

package com.base.controller.common;

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

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

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
@RequestMapping(value="/yanzheng")
public class RandomYan {
private static final Logger loger = LoggerFactory
.getLogger(RandomYan.class);
public static final char[] CHARS = { '2', '3', '4', '5', '6', '7', '8',
'9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M',
'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };

public static Random random = new Random();

public static String getRandomString() {
StringBuffer buffer = new StringBuffer();
for (int i = 0; i < 6; i++) {
buffer.append(CHARS[random.nextInt(CHARS.length)]);
}
return buffer.toString();
}

public static Color getRandomColor() {
return new Color(random.nextInt(255), random.nextInt(255),
random.nextInt(255));
}

public static Color getReverseColor(Color c) {
return new Color(255 - c.getRed(), 255 - c.getGreen(),
255 - c.getBlue());
}

@RequestMapping("/yanzhengma")
public void yanzhengma(HttpServletResponse response,
HttpServletRequest request) throws IOException {
response.setContentType("image/jpeg");
String randomString = getRandomString();
request.getSession(true).setAttribute("randomString", randomString);
loger.info(new StringBuilder().append("验证码:").append(randomString)
.toString());
int width = 100;
int height = 30;

Color color = getRandomColor();
Color reverse = getReverseColor(color);

BufferedImage bi = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
Graphics2D g = bi.createGraphics();
g.setFont(new Font(Font.SANS_SERIF, Font.BOLD, 20));
//g.setColor(Color.WHITE);
g.fillRect(0, 0, width, height);
g.setColor(reverse);
g.drawString(randomString, 10, 22);
for (int i = 0, n = random.nextInt(100); i < n; i++) {
g.drawRect(random.nextInt(width), random.nextInt(height), 1, 1);
}
// 转成JPEG格式
ServletOutputStream out = response.getOutputStream();
ImageIO.write(bi, "JPEG", out);
out.flush();
}

}