javaWeb如何實現隨機圖片驗證碼詳解

public class RandomValidateCodeUtil {


 public static final String RANDOMCODEKEY = "RANDOMVALIDATECODEKEY";//放到session中的key
 private String randString = "0123456789";//隨機產生隻有數字的字符串 private String
 //private String randString = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";//隨機產生隻有字母的字符串
 //private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//隨機產生數字與字母組合的字符串
 private int width = 95;// 圖片寬
 private int height = 25;// 圖片高
 private int lineSize = 40;// 幹擾線數量
 private int stringNum = 4;// 隨機產生字符數量

 private static final Logger logger = LoggerFactory.getLogger(RandomValidateCodeUtil.class);

 private Random random = new Random();

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

 /**
  * 獲得顏色
  */
 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);
 }

 /**
  * 生成隨機圖片
  */
 public String getRandcode(HttpServletRequest request, HttpServletResponse response) {
  HttpSession session = request.getSession();
  // BufferedImage類是具有緩沖區的Image類,Image類是用於描述圖像信息的類
  BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
  Graphics g = image.getGraphics();// 產生Image對象的Graphics對象,改對象可以在圖像上進行各種繪制操作
  g.fillRect(0, 0, width, height);//圖片大小
  g.setFont(new Font("Default", Font.ROMAN_BASELINE, 18));//字體大小
  g.setColor(getRandColor(110, 133));//字體顏色
  // 繪制幹擾線
  for (int i = 0; i <= lineSize; i++) {
   drowLine(g);
  }
  // 繪制隨機字符
  String randomString = "";
  for (int i = 1; i <= stringNum; i++) {
   randomString = drowString(g, randomString, i);
  }
  logger.info(randomString);
  g.dispose();
  try {
   // 將內存中的圖片通過流動形式輸出到客戶端
   ImageIO.write(image, "JPEG", response.getOutputStream());
  } catch (Exception e) {
   logger.error("將內存中的圖片通過流動形式輸出到客戶端失敗>>>> ", e);
  }
  return randomString;
 }

 /**
  * 繪制字符串
  */
 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;
 }

 /**
  * 繪制幹擾線
  */
 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);
 }

 /**
  * 獲取隨機的字符
  */
 public String getRandomString(int num) {
  return String.valueOf(randString.charAt(num));
 }
}

 @GetMapping(value = "/getVerify")
 @ApiOperation("生成圖片驗證碼")
 public void getVerify(HttpServletRequest request, HttpServletResponse response) {
  try {
   //設置相應類型,告訴瀏覽器輸出的內容為圖片
   response.setContentType("image/jpeg");
   //設置響應頭信息，告訴瀏覽器不要緩存此內容
   response.setHeader("Pragma", "No-cache");
   response.setHeader("Cache-Control", "no-cache");
   response.setDateHeader("Expire", 0);
   RandomValidateCodeUtil randomValidateCode = new RandomValidateCodeUtil();
   //輸出驗證碼圖片方法
   String randcode = randomValidateCode.getRandcode(request, response);
   
   // 將隨機生成的字符串放在redis中
   redisUtil.save("random", randcode);
   
   // 將生成的隨機字符串保存到session中
   // HttpSession session = request.getSession();
   // session.removeAttribute(RANDOMCODEKEY);
   // session.setAttribute(RANDOMCODEKEY, randomString);

  } catch (Exception e) {
   log.error("獲取驗證碼失敗>>>> ", e);
  }
 }

@PostMapping("/checkVerify")
  @ApiOperation("校驗圖形驗證碼")
  public String checkValidateCode(String verify) {
    // 校驗驗證碼
    try {
      // 從redis中獲取驗證碼
      String random = (String) redisUtil.findKey("random");

      // 從ression中獲取驗證碼
      HttpSession session = request.getSession();
      String random = session.getAttribute("random");

      log.info("獲取的隨機數 random = {}", random);
      if (org.springframework.util.StringUtils.isEmpty(verify)) {
        return "沒有輸入驗證碼";
      }
      if (verify.equals(random)) {
        redisUtil.delKey("random");
      } else {
        return "驗證碼錯誤";
      }
    } catch (Exception e) {
      log.error("驗證碼校驗失敗", e);
      return "服務器異常";
    }
    return "成功";
  }