java生成随机图片

@RequestMapping(method = POST, value = "/getVerify", produces = JSON_UTF8, consumes = JSON_UTF8)
public void getVerify(HttpServletRequest request, HttpServletResponse response) {
  try {
    response.setContentType("image/jpeg");  //设置相应类型,告诉浏览器输出的内容为图片
    response.setHeader("Pragma", "No-cache");  //设置响应头信息，告诉浏览器不要缓存此内容
    response.setHeader("Cache-Control", "no-cache");
    response.setDateHeader("Expire", 0);
    randomValidateCodeUtilService.getRandcode(request, response); //输出验证码图片方法
  } catch (Exception e) {
    logger.error("获取验证码失败", e);
  }
}

public static final String RANDOMCODEKEY = "RANDOMVALIDATECODEKEY";  //放到session中的key
//private String randString = "0123456789";  //随机产生只有数字的字符串
//private String randString = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";  //随机产生只有字母的字符串
private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";  //随机产生数字与字母组合的字符串

// 设置图片属性
private int width = 95;// 图片宽
private int height = 25;// 图片高
private int lineSize = 40;// 干扰线数量
private int stringNum = 4;// 随机产生字符数量

private static final Logger logger = LoggerFactory.getLogger(RandomValidateCodeUtilService.class);
private Random random = new Random();


/**
 * 生成随机图片
 */
public void getRandcode(HttpServletRequest request, HttpServletResponse response) {
  HttpSession session = request.getSession();
  // BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
  BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
  Graphics g = image.getGraphics();// 产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
  g.fillRect(0, 0, width, height);//图片大小
  g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 18));//字体大小
  g.setColor(getRandColor(110, 133));//字体颜色
  // 绘制干扰线
  for (int i = 0; i <= lineSize; i++) {
    drowLine(g);
  }
  // 绘制随机字符
  String randomString = "";
  for (int i = 1; i <= stringNum; i++) {
    randomString = drowString(g, randomString, i);
  }
  logger.info(randomString);
  // 将生成的随机字符串保存到session中
  session.removeAttribute(RANDOMCODEKEY);
  session.setAttribute(RANDOMCODEKEY, randomString);
  g.dispose();
  try {
    // 将内存中的图片通过流动形式输出到客户端
    ImageIO.write(image, "JPEG", response.getOutputStream());
  } catch (Exception e) {
    logger.error("将内存中的图片通过流动形式输出到客户端失败", e);
  }
}


/**
 * 获得颜色
 */
private Color getRandColor(int fc, int bc) {
  if (fc > 255)
    fc = 255;
  if (bc > 255)
    bc = 255;
  int r = fc + random.nextInt(bc - fc - 16);
  int g = fc + random.nextInt(bc - fc - 14);
  int b = fc + random.nextInt(bc - fc - 18);
  return new Color(r, g, b);
}


/**
 * 绘制干扰线
 */
private void drowLine(Graphics g) {
  int x = random.nextInt(width);
  int y = random.nextInt(height);
  int xl = random.nextInt(13);
  int yl = random.nextInt(15);
  g.drawLine(x, y, x + xl, y + yl);
}


/**
 * 绘制字符串
 */
private String drowString(Graphics g, String randomString, int i) {
  g.setFont(getFont());
  g.setColor(new Color(random.nextInt(101), random.nextInt(111), random
          .nextInt(121)));
  String rand = String.valueOf(getRandomString(random.nextInt(randString
          .length())));
  randomString += rand;
  g.translate(random.nextInt(3), random.nextInt(3));
  g.drawString(rand, 13 * i, 16);
  return randomString;
}


/**
 * 获取随机的字符
 */
public String getRandomString(int num) {
  return String.valueOf(randString.charAt(num));
}


/**
 * 获得字体
 */
private Font getFont() {
  return new Font("Fixedsys", Font.CENTER_BASELINE, 18);
}