【java】圖片驗證碼的隨機產生

1.情境還原    最近在項目的前端工程中，有這樣的需求：隨機產生驗證碼，點擊圖片驗證碼也可以更換驗證碼，並且傳輸到後台驗證。 效果UI圖：

2.實現方案 1.前端介面布置代碼：

<div class="checkCode" style="padding: 5px 0px 10px; position: relative;">  <INPUT name="checkcode" class="ipt"  id="image1"   type="text" placeholder="請輸入驗證碼" value="">  <img  src="http://localhost:8080/ImageChack" id="image2" border="" class="verifyimg" height="30px" width="120 px" onClick="this.src='http://localhost:8080/ImageChack?redirect='+Math.random()"/></div>

 圖片驗證碼的點擊方法（更換驗證碼）

onClick="this.src='http://localhost:8080/ImageChack?redirect='+Math.random()"

2.隨機產生驗證碼的的servlet:

public class ImageChack extends HttpServlet {   private static final long serialVersionUID = 1L;      private Font getFont(){      Random random = new Random();      Font[] font = new Font[5];      font[0] = new Font("Ravie", Font.PLAIN, 24);          font[1] = new Font("Antique Olive Compact", Font.PLAIN, 24);          font[2] = new Font("Forte", Font.PLAIN, 24);          font[3] = new Font("Wide Latin", Font.PLAIN, 24);          font[4] = new Font("Gill Sans Ultra Bold", Font.PLAIN, 24);          return font[random.nextInt(5)];     }      protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {      //設定回應標頭資訊      response.setContentType("image/jpeg");      //指定頁面不緩衝      response.setHeader("Pragma", "No-cache");        response.setHeader("Cache-Control", "No-cache");        response.setDateHeader("Expires", 0);       //擷取輸出資料流      OutputStream os = response.getOutputStream();      //指定寬高      int width = 120,height = 30;      //指定寬高和bufferedImage對象      BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);      //畫筆畫在image 上      Graphics g = image.getGraphics();       Color c = g.getColor();      g.fillRect(0, 0, width, height);            char[] ch = "ABCDEFGHJKLMNPQRSTUVWXYZabcdefghjklmnpqrstuvwxyz23456789".toCharArray();      int len = ch.length;      String res = "";      Random random = new Random();      for(int i=0; i<5; i++){         //設定字型         g.setFont(getFont());         String rand = new Character(ch[random.nextInt(len)]).toString();         res+=rand;         //設定隨機顏色         g.setColor(new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255)));         g.drawString(rand, 20*i+6, 25);      }      //產生幹擾點//    for(int i=0; i<6; i++){//       int x1 = random.nextInt(width);//       int y1 = random.nextInt(height);//       g.setColor(new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255)));//       g.drawOval(x1, y1, width, height);//    }      //將畫筆顏色還原      g.setColor(c);      g.dispose();      //將驗證碼儲存到session      request.getSession().setAttribute("imageChack", res);      System.out.println(res.toLowerCase());      //輸出映像      ImageIO.write(image, "JPEG", os);         }   protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {      doGet(request, response);   }}

3.在web.xml中配置ImageChack

<!--初始化圖片驗證servlet--><servlet>    <servlet-name>ImageChack</servlet-name>    <servlet-class>org.yxm.cms.controller.ImageChack</servlet-class></servlet><servlet-mapping>    <servlet-name>ImageChack</servlet-name>    <url-pattern>/ImageChack</url-pattern></servlet-mapping>

4.在loginController的代碼邏輯：

@RequestMapping(value = "/login", method = RequestMethod.POST)public String login(@RequestParam String username, @RequestParam String password,                    Model model, HttpServletRequest request) {  User user = userService.findByUserNamePassword(username, password);  //使用者輸入  String inputStr = request.getParameter("checkcode");  //隨機碼產生 String picStr = (String) request.getSession().getAttribute("imageChack");  System.out.print("使用者輸入"+inputStr);  System.out.print("隨機碼產生"+picStr);  if (user == null) {    model.addAttribute("login_error", "登入名稱或密碼錯誤。");    return "login/login";  }  if(!inputStr.equals(picStr)){    model.addAttribute("verfied_error", "圖片驗證碼輸入有錯。");    return "login/login";  }  List<Permission> permissions = userService.listUserPermissions(user.getId());  List<Integer> gids = userService.listUserGids(user.getId());  List<Permission> groupPermissions = groupService.listGroupsPermissions(ListUtil.list2array(gids));  for (Permission p : groupPermissions) {    if (!permissions.contains(p)) {      permissions.add(p);    }  }  request.getSession().setAttribute(Constant.LOGIN_USER, user);  request.getSession().setAttribute(Constant.LOGIN_PERMISSIONS, permissions);  return "redirect:/admin/index";}