在java后台中生成验证码的ImageIO传到前端页面显示，同时把验证码的value值传入session 中用于与用户输入的验证码进行匹配，在用户验证中使用ajax技术，在不刷新页面的同时进行验证码验证。
程序结构图：
VerifyCodeUtils程序主要内容为通过java生成验证码的图片，以及验证码的value值，程序如下：
package utils; import java.awt.Color; import java.awt.Font; import java.awt.Graphics2D; import java.awt.image.BufferedImage; import java.util.HashMap; import java.util.Map; import java.util.Random; public class VerifyCodeUtils { private static BufferedImage image = null; private static Random random = new Random(); //在自己定义的一些数中，生成4位随机数 public static String getVerifyCode() { String str = ""; char[] code = new char[]{'A','B','C','D','E','F','G','H','I','J','K','L','M','N','P','Q','R','S','T','U', 'V','W','X','Y','Z','a','b','c','d','e','f','g','h','i','j','k','m','n','p','q','r','s','t', 'u','v','w','x','y','z','2','3','4','5','6','7','8','9'}; Random random = new Random(); for(int i = 0; i < 4; i++) { str += String.valueOf(code[random.nextInt(code.length)]); } return str; } //生成验证码图像 public static Map getVerifyCode(int width, int heigth) { VerifyCodeUtils.image = new BufferedImage(width, heigth, BufferedImage.TYPE_INT_RGB); Graphics2D g = (Graphics2D) VerifyCodeUtils.image.getGraphics(); String verifyCode = getVerifyCode(); Map map = new HashMap(); map.put("verifyCode", verifyCode); //将图像填充为白色 g.setColor(Color.WHITE); g.fillRect(0, 0, width, heigth); //设置字体 g.setFont(new Font("宋体", Font.BOLD + Font.ITALIC, heigth-10)); //画边框。 g.setColor(VerifyCodeUtils.getColor()); g.drawRect(0, 0, width, heigth); //随机产生干扰线，使图象中的认证码不易被其它程序探测到 g.setColor(Color.BLACK); for (int i = 0; i < 50; i++) { int x = VerifyCodeUtils.random.nextInt(width); int y = VerifyCodeUtils.random.nextInt(heigth); int xl = VerifyCodeUtils.random.nextInt(5); int yl = VerifyCodeUtils.random.nextInt(5); g.setColor(getColor()); g.drawLine(x, y, x + xl, y + yl); } char c; for(int i = 0; i < 4; i++) { c = verifyCode.charAt(i); g.drawString(c+"", i*20+40, heigth-10); } map.put("image", VerifyCodeUtils.image); return map; } //随机化颜色 public static Color getColor() { int red = 0, green = 0, blue = 0; // 产生随机的颜色分量来构造颜色值，这样输出的每位数字的颜色值都将不同。 red = VerifyCodeUtils.random.nextInt(255); green = VerifyCodeUtils.random.nextInt(255); blue = VerifyCodeUtils.random.nextInt(255); return new Color(red,green,blue); } }
VerifyCodeServlet把VerifyCodeUtils生成的验证码图片通过io流传入前端显示，代码如下：
package Servlet; import java.awt.image.BufferedImage; import java.io.IOException; import java.util.Map; import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import utils.VerifyCodeUtils; /** * Servlet implementation class VerifyCodeServlet */ @WebServlet("/") public class VerifyCodeServlet extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public VerifyCodeServlet() { super(); // TODO Auto-generated constructor stub } /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setHeader("Expires", "-1"); response.setHeader("Cache-Control", "no-cache"); response.setHeader("Pragma", "no-cache"); response.setHeader("Content-type", "image/jpeg"); Map map = VerifyCodeUtils.getVerifyCode(223, 50); //把verifyCode的数值传入session中用于验证用户输入的验证码是否正确 request.getSession().setAttribute("verifyCode", map.get("verifyCode").toString().toUpperCase()); //通过IO流传入前端显示 ImageIO.write((BufferedImage) map.get("image"), "jpg", response.getOutputStream()); } /** * @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); } }
页面jsp代码如下：
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <base id="base" href="${pageContext.request.contextPath}"> <title>验证码测试界面</title> <style> div{float:left;} input{width:223px;height:31px;margin-right:20px;} img{width:223px;height:35px;} p{margin:10px;} </style> </head> <body> <script src="${pageContext.request.contextPath}/JS/demo.js"></script> <div> <input type="text" name="verifyCode" id="verifyCode" placeholder="验证码" onblur="check_verifyCode()"> </div> <div> <img src="${pageContext.request.contextPath}/servlet/VerifyCodeServlet"/> </div> <div> <p id = "tip"></p> </div> </body> </html>
js 实现ajax代码如下：
/** * */ function check_verifyCode(){ var XMLHttpReqVerifyCode = null; var url =document.getElementById("base").href +"/servlet/TestVerifyCodeServlet"; var verifyCode = document.getElementById("verifyCode").value; var tip = document.getElementById("tip"); var errorTip = "输入的验证码不正确"; var successTip = "输入的验证码正确"; tip.innerHTML=errorTip; if(verifyCode==null || verifyCode==""){ tip.innerHTML=errorTip; tip.style.color = "red"; }else{ if(window.XMLHttpRequest) { //DOM2浏览器 XMLHttpReqVerifyCode = new XMLHttpRequest(); } else if(window.ActiveXObject) { //使用json语法创建数组 var MSXML = ['MSXML2.XMLHTTP.5.0', 'MSXML2.XMLHTTP.4.0', 'MSXML2.XMLHTTP.3.0', 'MSXML2.XMLHTTP', 'Microsoft.XMLHTTP']; for(var i = 0; i < MSXML.length; i++) { try{ XMLHttpReqVerifyCode = new ActiveXObject(MSXML[i]); } catch(e) { } } } XMLHttpReqVerifyCode.open("POST",url, true); XMLHttpReqVerifyCode.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"); XMLHttpReqVerifyCode.onreadystatechange = function testVerifyCodeServletResponse(){ if(XMLHttpReqVerifyCode.readyState == 4 && (XMLHttpReqVerifyCode.status == 200 || XMLHttpReqVerifyCode.status == 304)) { if(XMLHttpReqVerifyCode.responseText == 1){ tip.innerHTML = successTip; tip.style.color = "green"; }else if(XMLHttpReqVerifyCode.responseText == 0){ tip.innerHTML = errorTip; tip.style.color = "red"; } } } XMLHttpReqVerifyCode.send("code="+verifyCode); } //ajax前后台交互 function createXMLHttpRequest(XMLHttpReq) { if(window.XMLHttpRequest) { //DOM2浏览器 XMLHttpReq = new XMLHttpRequest(); } else if(window.ActiveXObject) { //使用json语法创建数组 var MSXML = ['MSXML2.XMLHTTP.5.0', 'MSXML2.XMLHTTP.4.0', 'MSXML2.XMLHTTP.3.0', 'MSXML2.XMLHTTP', 'Microsoft.XMLHTTP']; for(var i = 0; i < MSXML.length; i++) { try{ XMLHttpReq = new ActiveXObject(MSXML[i]); } catch(e) { } } return XMLHttpReq; } } }
TestVerifyCodeServlet与js交互代码为：
package Servlet; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * Servlet implementation class TestVerifyCodeServlet */ @WebServlet("/TestVerifyCodeServlet") public class TestVerifyCodeServlet extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public TestVerifyCodeServlet() { 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 String codeTrue = (String) request.getSession().getAttribute("verifyCode"); String codeInput = request.getParameter("code"); System.out.println(codeInput); response.setContentType("text/html;charset=utf-8"); PrintWriter out = response.getWriter();//打印流 if(codeInput!=null){ if(codeInput.toUpperCase().equals(codeTrue)){ out.println("1"); }else{ out.println("0"); } } } /** * @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); } }
xml代码为
<"1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"> <display-name></display-name> <welcome-file-list> <welcome-file>demo.jsp</welcome-file> </welcome-file-list> <servlet> <servlet-name>VerifyCodeServlet</servlet-name> <servlet-class>Servlet.VerifyCodeServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>VerifyCodeServlet</servlet-name> <url-pattern>/servlet/VerifyCodeServlet</url-pattern> </servlet-mapping> <servlet> <servlet-name>TestVerifyCodeServlet</servlet-name> <servlet-class>Servlet.TestVerifyCodeServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>TestVerifyCodeServlet</servlet-name> <url-pattern>/servlet/TestVerifyCodeServlet</url-pattern> </servlet-mapping> </web-app>
结果显示：
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