java web開發之servlet圖形驗證碼功能的實現

一驗證碼的由來

在web項目開發中，為了防止部分人使用自動工具（如：自動註冊機）等進行批量的數據處理，在不同的功能節點部分，添加了驗證碼進行驗證，達到對自動軟件的屏蔽效果

最經典的應用如：網站註冊圖形驗證碼；接下來，通過java技術，結合servlet實現一個網站註冊需要的圖形驗證碼程序，提供大家參考。

二實現註冊頁面圖形驗證碼效果

1. 創建web項目：java_servlet_verifyimg

2. 創建自動生成圖形驗證碼的控制器――VerifyImgServlet

 package com.phome.util;import java.awt.Color;import java.awt.Font;import java.awt.Graphics2D;import java.awt.image.BufferedImage;import java.io.IOException;import java.util.Random;import javax.servlet.ServletException;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.sun.image.codec.jpeg.JPEGCodec;import com.sun.image.codec.jpeg.JPEGImageEncoder;public class VerifyImgServlet extends HttpServlet { /** * */ private static final long serialVersionUID = 1L; // 設置隨機字符字典。其中不包含0,o,1,I等難以辨認的字符public static final char[] CHARS = { '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'j', 'k', 'l', 'm', 'n', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z' }; public static Random random = new Random(); // 隨機數對象public static String getRandomString() { StringBuffer buffer = new StringBuffer(); // 字符串緩存for (int i = 0; i < 6; i++) // 六次循環獲取字符{ buffer.append(CHARS[random.nextInt(CHARS.length)]); // 每次隨機取一個字符} return buffer.toString(); } public static Color getRandomColor() { return new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255)); } public static Color getReverseColor(Color c) { return new Color(255 - c.getRed(), 255 - c.getGreen(), 255 - c.getBlue()); } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("image/jpeg"); // 設置輸出類型不可省略String randomString = getRandomString(); // 調用生成隨機字符串方法獲取並接受隨機字符串request.getSession(true).setAttribute("randomString", randomString); // 將字符串存儲到Session中int width = 100; // 圖片寬度int height = 30; // 圖片高度Color color = getRandomColor(); // 獲取隨機顏色用於背景色Color reverse = getReverseColor(color); // 反色用於前景色BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // 創建一個彩色圖片Graphics2D g = bi.createGraphics(); // 獲取繪圖對象g.setFont(new Font(Font.SANS_SERIF, Font.BOLD, 16)); // 設置字體g.setColor(color); // 設置顏色g.fillRect(0, 0, width, height); // 繪製背景g.setColor(reverse); // 設置顏色g.drawString(randomString, 18, 20); // 繪製隨機字符for (int i = 0, n = random.nextInt(100); i < n; i++) // 畫最多一百個噪音點{ g.drawRect(random.nextInt(width), random.nextInt(height), 1, 1); // 隨機噪音點} ServletOutputStream out = response.getOutputStream(); // 好像是獲取輸出流JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out); // 編碼器encoder.encode(bi); // 對圖片進行編碼out.flush(); // 輸出到客戶端} public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doGet(request, response); }}

3. 創建註冊控制器――RegistServlet

 package com.phome.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;/** * 註冊控制器* @author ZuoYi * */public class RegistServlet extends HttpServlet{ /** * */ private static final long serialVersionUID = 1L; @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { this.doPost(req, resp); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // 從session中獲取註冊隨機驗證碼HttpSession session = req.getSession(); String randomString = (String)session.getAttribute("randomString"); // 獲取用戶輸入驗證碼String inputRandomString = req.getParameter("randomStr"); // 判斷驗證碼通過，模擬進行註冊if (randomString.equals(inputRandomString)) { req.setAttribute("resinfo", "恭喜！註冊成功！"); } else { req.setAttribute("resinfo", "驗證碼輸入有誤，請檢查後重新進行註冊！"); } // 註冊成功或者失敗，都跳轉到result.jsp頁面，查看註冊結果。 。 。 req.getRequestDispatcher("result.jsp").forward(req, resp); } }

4. 配置servlet

 <?xml version="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_3_0.xsd" id="WebApp_ID" version="3.0"> <display-name>simg</display-name> <!-- 配置用戶註冊servlet --> <servlet> <servlet-name>registservlet</servlet-name> <servlet-class>com.phome.servlet.RegistServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>registservlet</servlet-name> <url-pattern>/regist.action</url-pattern> </servlet-mapping> <!-- 配置圖形驗證碼servlet --> <servlet> <servlet-name>verifyimg</servlet-name> <servlet-class>com.phome.servlet.VerifyImgServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>verifyimg</servlet-name> <url-pattern>/verifyimg.action</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.html</welcome-file> <welcome-file>index.htm</welcome-file> <welcome-file>index.jsp</welcome-file> <welcome-file>default.html</welcome-file> <welcome-file>default.htm</welcome-file> <welcome-file>default.jsp</welcome-file> </welcome-file-list></web-app>

5. 創建註冊視圖測試頁面――regist.jsp

 <%@ page language="java" import="java.util.*" pageEncoding="GB18030"%><%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" rel="external nofollow" > <title>My JSP 'index.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" rel="external nofollow" > --> </head> <body> <form action="${pageContext.request.contextPath}/regist.action" method="post"> 用戶名：<input type="text" name="username"/> <br /> 密碼：<input type="text" name="password"/> <br /> 請輸入驗證碼進行註冊： <img src="${pageContext.request.contextPath }/verifyimg.action"/> <input type="text" name="randomStr"/> <br /> <input type="submit" value="regist"/> </form> </body></html>

5.1 創建註冊結果頁面――result.jsp

 <%@ page language="java" import="java.util.*" pageEncoding="GB18030"%><%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" rel="external nofollow" > <title>My JSP 'index.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" rel="external nofollow" > --> </head> <body> ${requestScope.resinfo } </body></html>

6.測試

（1）a.打開瀏覽器，輸入測試地址：http://localhost:8080/java_servlet_verifyimg；出現如下圖所示頁面

b.輸入註冊賬號、密碼和驗證碼後點擊regist提交

c.測試結果，跳轉會註冊頁面，提示註冊成功

（2）打開註冊頁面

輸入錯誤註冊碼

測試結果頁面

over!

以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持武林網。