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java验证码小程序 java实现验证码小程序

糖拌西红柿 人气:0
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手动制作java的验证码,具体内容如下

Web应用验证码的组成:

(1)输入框

(2)显示验证码的图片

验证码的制作流程:

生成验证码的容器使用 j2ee的servlet

生成图片需要的类:

(1) BufferedImage 图像数据缓冲区

(2)Graphic绘制图片

(3)Color获取颜色

(4)Random生成随机数

(5)ImageIO输入图片

具体实现流程:

(1)定义一个Servlet,用于生成验证码

(2)定已BufferedImage对象,主要作用就是制作一个图片缓冲区,作为图片的一个临时容器。

(3)获得Graphic对象,画图的“背景”,理解为"画布"

(4)通过Random生成随机数,来制作验证信息

(5)通过Graphic操作,进行具体画图

(6)信息存至session中

(7)使用ImageIO输出生成的图片,通过设置ImageIO的 write()方法中的out参数,response.getOutputStream(),将图片传至前台

(8)制作验证用的servlet,提取session中的数据进行验证(这里采用ajax异步方法)

具体代码实现(Web端验证码实例)

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>java验证码</title>
<script src="https://apps.bdimg.com/libs/jquery/2.1.4/jquery.min.js"></script>
</head>
<body>
 验证码输入:<input type="text" name="checkcode">  
 <img id="codeimg" alt="验证码" src="ImageServlet">
 <a href="javascript:reloadCode();">看不出清楚?</a><br/>
 <input type="submit" value="提交">
 <div id="info" style="color:red;"></div>
 
 <script type="text/javascript">
 $(function(){
  //ajax异步传验证码至后台
  $("input[type=submit]").click(function(){
   $.post("CheckCode",
     {"code":$("input[name=checkcode]").val()},
     function(data,textStatus)
     {
      console.log(textStatus);
      $("#info").html(data);
     },"text");
  });
 })
 //js刷新,重新请求页面,获得新的验证码
 function reloadCode(){
  var time = new Date().getTime();//创建不同的时间
  $("#codeimg").attr("src","ImageServlet?time="+time);//因为时间参数不同,请求重新
 }
 </script> 
</body>
</html>

ImageServlet类(验证码生成部分)

@WebServlet("/ImageServlet")
public class ImageServlet extends HttpServlet {
 private static final long serialVersionUID = 1L;
  
 /**
  * @see HttpServlet#HttpServlet()
  */
 public ImageServlet() {
  super();
  // TODO Auto-generated constructor stub
 }

 /**
  * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
  */
 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  // TODO Auto-generated method stub
  BufferedImage bimg = new BufferedImage(68, 22, BufferedImage.TYPE_INT_RGB);
  Graphics g = bimg.getGraphics();
  Color color = new Color(200,151,255);//颜色生成
  g.setColor(color);
  g.fillRect(0, 0, 68, 22);
  char[] ch="ABCDEFGHJIKLMNOPQRSTUVWXYZ0123456789".toCharArray();//获得一个含有字母和数字的数组,后续随机从中获取字符
  Random random = new Random(); //创建随机数
  int len = ch.length,index;
  StringBuffer sBuffer = new StringBuffer();
  
  //循环产生4个随机字符
  for(int i = 0 ;i<4;i++)
  {
   index = random.nextInt(len);//产生随机字母与数字
   g.setColor(new Color(random.nextInt(88),random.nextInt(120),random.nextInt(90)));//创建随机颜色
   g.drawString(ch[index]+"", (i)*15+3, 18);
   sBuffer.append(ch[index]);//将随机获取的字符放置缓冲串中
  }
  request.getSession().setAttribute("newCode", sBuffer.toString());//存至session便于后续验证
  ImageIO.write(bimg, "JPG", response.getOutputStream());//通过ImageIO输出图片,并传至前台
 }

 /**
  * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
  */
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  // TODO Auto-generated method stub
  doGet(request, response);
 }

}

CheckCode(验证码验证servlet) 

@WebServlet("/CheckCode")
public class CheckCode extends HttpServlet {
 private static final long serialVersionUID = 1L;
  
 /**
  * @see HttpServlet#HttpServlet()
  */
 public CheckCode() {
  super();
  // TODO Auto-generated constructor stub
 }

 /**
  * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
  */
 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  // TODO Auto-generated method stub
  response.setCharacterEncoding("utf-8");
  String code = request.getParameter("code").toUpperCase();//获取传来验证码并进行大小写转换
  String result=null;
  if(request.getSession().getAttribute("newCode").equals(code))
  {
   result="验证成功!";
   response.getWriter().append(result);
  }
  else {
   result="验证码错误!";
   response.getWriter().append(result);
  }
 }

 /**
  * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
  */
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  // TODO Auto-generated method stub
  doGet(request, response);
 }

}

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