JAVA验证码工具实例代码

package com.lhy.web.servlet;import java.awt.BasicStroke;import java.awt.Color;import java.awt.Font;import java.awt.Graphics2D;import java.awt.image.BufferedImage;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.OutputStream;import java.util.Random;import javax.imageio.ImageIO;public class VerifyCode {  private int w = 70;//图片长  private int h = 35;//图片宽   private Random r = new Random();//Random类 生成随机数   // 列举验证图片中验证码的字体类型   //{"宋体", "华文楷体", "黑体", "华文新魏", "华文隶书", "微软雅黑", "楷体_GB2312"}  private String[] fontNames = {"宋体", "华文楷体", "黑体", "微软雅黑", "楷体_GB2312"};  // 验证码可选字符  private String codes="23456789abcdefghjkmnopqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ";  // 背景色  private Color bgColor = new Color(255, 255, 255);  // 验证码上的文本  private String text ;  // 生成随机的颜色  private Color randomColor () {      int red = r.nextInt(150);      int green = r.nextInt(150);      int blue = r.nextInt(150);      return new Color(red, green, blue);  }  // 生成随机的字体  private Font randomFont () {        int index = r.nextInt(fontNames.length);        String fontName = fontNames[index];//生成随机的字体名称        int style = r.nextInt(4);//生成随机的样式, 0(无样式), 1(粗体), 2(斜体), 3(粗体+斜体)        int size = r.nextInt(5) + 24; //生成随机字号, 24 ~ 28        return new Font(fontName, style, size);  }  // 画干扰线  private void drawLine (BufferedImage image) {      int num = 3;//一共画3条      Graphics2D g2 = (Graphics2D)image.getGraphics();      for(int i = 0; i < num; i++) {//生成两个点的坐标，即4个值        int x1 = r.nextInt(w);        int y1 = r.nextInt(h);        int x2 = r.nextInt(w);        int y2 = r.nextInt(h);         g2.setStroke(new BasicStroke(1.5F));         g2.setColor(Color.BLUE); //干扰线是蓝色        g2.drawLine(x1, y1, x2, y2);//画线      }  }  // 随机生成一个字符  private char randomChar () {      int index = r.nextInt(codes.length());      return codes.charAt(index);  }  // 创建BufferedImage  private BufferedImage createImage () {      //宽，高，图片的类型      BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);       Graphics2D g2 = (Graphics2D)image.getGraphics();       g2.setColor(this.bgColor);      g2.fillRect(0, 0, w, h);       return image;  }  // 返回验证码图片上的文本  public String getText () {      return text;  }  // 保存图片到指定的输出流  public static void output (BufferedImage image, OutputStream out)           throws IOException {      ImageIO.write(image, "JPEG", out);  }  // 调用这个方法得到验证码    public BufferedImage getImage () {        BufferedImage image = createImage();//创建图片缓冲区         Graphics2D g2 = (Graphics2D)image.getGraphics();//得到绘制环境        StringBuilder sb = new StringBuilder();//用来装载生成的验证码文本        // 向图片中画4个字符        for(int i = 0; i < 4; i++) {//循环四次，每次生成一个字符          String s = randomChar() + "";//随机生成一个字母           sb.append(s); //把字母添加到sb中          float x = i * 1.0F * w / 4; //设置当前字符的x轴坐标          g2.setFont(randomFont()); //设置随机字体          g2.setColor(randomColor()); //设置随机颜色          g2.drawString(s, x, h-5); //画图        }        this.text = sb.toString(); //把生成的字符串赋给了this.text        drawLine(image); //添加干扰线        return image;        }    public static void main(String[] args) throws FileNotFoundException, IOException {      VerifyCode vc = new VerifyCode();//创建VerifyCode类的对象      BufferedImage bi = vc.getImage();//调用getImge()方法获得一个BufferedImage对象      VerifyCode.output(bi, new FileOutputStream("C:/验证码3.jpg"));//调用静态方法output()方法将图片保存在文件输出流中      System.out.println(vc.getText());//在控制台上打印验证码的文本值    }}

package com.lhy.web.servlet;import java.awt.image.BufferedImage;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class VerifyCodeServlet extends HttpServlet {  public void doGet(HttpServletRequest request, HttpServletResponse response)      throws ServletException, IOException {    /*     * 1. 生成图片     * 2. 保存图片上的文本到session域中     * 3. 把图片响应给客户端     */    VerifyCode vc = new VerifyCode();    BufferedImage image = vc.getImage();    request.getSession().setAttribute("session_vcode", vc.getText());//保存图片上的文本到session域    VerifyCode.output(image, response.getOutputStream());  }}

package com.lhy.web.servlet;import java.io.IOException;import javax.servlet.RequestDispatcher;import javax.servlet.ServletException;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;public class LoginServlet extends HttpServlet {  public void doPost(HttpServletRequest request, HttpServletResponse response)      throws ServletException, IOException {    /*     * 校验验证码     * 1. 从session中获取正确的验证码     * 2. 从表单中获取用户填写的验证码     * 3. 进行比较！     * 4. 如果相同，向下运行，否则保存错误信息到request域，转发到login.jsp     */    String sessionCode = (String) request.getSession().getAttribute("session_vcode");    String paramCode = request.getParameter("verifyCode");    if(!paramCode.equalsIgnoreCase(sessionCode)) {      request.setAttribute("msg", "验证码错误！");      request.getRequestDispatcher("/login.jsp").forward(request, response);      return;    }    /*     * 1. 获取表单数据     */    // 处理中文问题    request.setCharacterEncoding("utf-8");    // 获取    String username = request.getParameter("username");    String password = request.getParameter("password");    /*     * 2. 校验用户名和密码是否正确     */    if("itcast".equalsIgnoreCase(username)) {//登录成功      /*       * 附加项：把用户名保存到cookie中，发送给客户端浏览器       * 当再次打开login.jsp时，login.jsp中会读取request中的cookie，把它显示到用户名文本框中       */      Cookie cookie = new Cookie("uname", username);//创建Cookie      cookie.setMaxAge(60*60*24);//设置cookie命长为1天      response.addCookie(cookie);//保存cookie      /*       * 3. 如果成功       *  > 保存用户信息到session中       *  > 重定向到succ1.jsp       */      HttpSession session = request.getSession();//获取session      session.setAttribute("username", username);//向session域中保存用户名      response.sendRedirect("/Test/succ1.jsp");    } else {//登录失败      /*       * 4. 如果失败       *  > 保存错误信息到request域中       *  > 转发到login.jsp       */      request.setAttribute("msg", "用户名或密码错误!");      RequestDispatcher qr = request.getRequestDispatcher("/login.jsp");//得到转发器      qr.forward(request, response);//转发    }  }  }

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head>  <base href="<%=basePath%>" rel="external nofollow" >  <title>My JSP 'login.jsp' starting page</title>  <meta http-equiv="pragma" content="no-cache">  <meta http-equiv="cache-control" content="no-cache">  <meta http-equiv="expires" content="0">    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">  <meta http-equiv="description" content="This is my page">  <!--  <link rel="stylesheet" type="text/css" href="styles.css" rel="external nofollow" >  --><script type="text/javascript">function _change() {  /*  1. 得到img元素  2. 修改其src  */  var imgEle = document.getElementById("img");  imgEle.src = "<%=basePath%>servlet/VerifyCodeServlet?a=" + new Date().getTime();}</script> </head> <body><%-- 本页面提供登录表单，还要显示错误信息 --%><h1>登录</h1><%/*读取名为uname的Cookie!如果为空显示：""如果不为空显示：Cookie的值*/String uname = "";Cookie[] cs = request.getCookies();//获取请求中所有的cookieif(cs != null) {// 如果存在cookie  for(Cookie c : cs) {//循环遍历所有的cookie    if("uname".equals(c.getName())) {//查找名为uname的cookie      uname = c.getValue();//获取这个cookie的值，给uname这个变量    }  }}%><%  String message = "";  String msg = (String)request.getAttribute("msg");//获取request域中的名为msg的属性  if(msg != null) {    message = msg;  }%><font color="red"><b><%=message %> </b></font><form action="servlet/LoginServlet" method="post">      <%-- 把cookie中的用户名显示到用户名文本框中 --%>  用户名：<input type="text" name="username" value="<%=uname%>"/><br/>  密　码：<input type="password" name="password"/><br/>  验证码：<input type="text" name="verifyCode" size="3"/>      <img id="img" src="<%=basePath%>servlet/VerifyCodeServlet"/>      <a href="javascript:_change()" rel="external nofollow" >换一张</a>      <br/>  <input type="submit" value="登录"/></form> </body></html>

<body><h1>succ1</h1><%String username = (String)session.getAttribute("username");if(username == null) {  /*  1. 向request域中保存错误信息，转发到login.jsp  */  request.setAttribute("msg", "您还没有登录!请先登录!");  request.getRequestDispatcher("/login.jsp").forward(request, response);  return;}%>

 </body></html>

<servlet>  <servlet-name>LoginServlet</servlet-name>  <servlet-class>com.lhy.web.servlet.LoginServlet</servlet-class> </servlet>  <servlet-mapping>  <servlet-name>LoginServlet</servlet-name>  <url-pattern>/servlet/LoginServlet</url-pattern> </servlet-mapping> <servlet>  <servlet-name>VerifyCodeServlet</servlet-name>  <servlet-class>com.lhy.web.servlet.VerifyCodeServlet</servlet-class> </servlet>  <servlet-mapping>  <servlet-name>VerifyCodeServlet</servlet-name>  <url-pattern>/servlet/VerifyCodeServlet</url-pattern> </servlet-mapping>