JAVA驗證碼工具實例代碼

工具類：

 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;//圖片長private int h = 35;//圖片寬private Random r = new Random();//Random類生成隨機數// 列舉驗證圖片中驗證碼的字體類型//{"宋體", "華文楷體", "黑體", "華文新魏", "華文隸書", "微軟雅黑", "楷體_GB2312"} private String[] fontNames = {"宋體", "華文楷體", "黑體", "微軟雅黑", "楷體_GB2312"}; // 驗證碼可選字符private String codes="23456789abcdefghjkmnopqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ"; // 背景色private Color bgColor = new Color(255, 255, 255); // 驗證碼上的文本private String text ; // 生成隨機的顏色private Color randomColor () { int red = r.nextInt(150); int green = r.nextInt(150); int blue = r.nextInt(150); return new Color(red, green, blue); } // 生成隨機的字體private Font randomFont () { int index = r.nextInt(fontNames.length); String fontName = fontNames[index];//生成隨機的字體名稱int style = r.nextInt(4);//生成隨機的樣式, 0(無樣式), 1(粗體), 2(斜體), 3(粗體+斜體) int size = r.nextInt(5) + 24; //生成隨機字號, 24 ~ 28 return new Font(fontName, style, size); } // 畫干擾線private void drawLine (BufferedImage image) { int num = 3;//一共畫3條Graphics2D g2 = (Graphics2D)image.getGraphics(); for(int i = 0; i < num; i++) {//生成兩個點的坐標，即4個值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); //干擾線是藍色g2.drawLine(x1, y1, x2, y2);//畫線} } // 隨機生成一個字符private char randomChar () { int index = r.nextInt(codes.length()); return codes.charAt(index); } // 創建BufferedImage private BufferedImage createImage () { //寬，高，圖片的類型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; } // 返回驗證碼圖片上的文本public String getText () { return text; } // 保存圖片到指定的輸出流public static void output (BufferedImage image, OutputStream out) throws IOException { ImageIO.write(image, "JPEG", out); } // 調用這個方法得到驗證碼public BufferedImage getImage () { BufferedImage image = createImage();//創建圖片緩衝區Graphics2D g2 = (Graphics2D)image.getGraphics();//得到繪製環境StringBuilder sb = new StringBuilder();//用來裝載生成的驗證碼文本// 向圖片中畫4個字符for(int i = 0; i < 4; i++) {//循環四次，每次生成一個字符String s = randomChar() + "";//隨機生成一個字母sb.append(s); //把字母添加到sb中float x = i * 1.0F * w / 4; //設置當前字符的x軸坐標g2.setFont(randomFont()); //設置隨機字體g2.setColor(randomColor()); //設置隨機顏色g2.drawString(s, x, h-5); //畫圖} this.text = sb.toString(); //把生成的字符串賦給了this.text drawLine(image); //添加干擾線return image; } public static void main(String[] args) throws FileNotFoundException, IOException { VerifyCode vc = new VerifyCode();//創建VerifyCode類的對象BufferedImage bi = vc.getImage();//調用getImge()方法獲得一個BufferedImage對象VerifyCode.output(bi, new FileOutputStream("C:/驗證碼3.jpg"));//調用靜態方法output()方法將圖片保存在文件輸出流中System.out.println(vc.getText());//在控制台上打印驗證碼的文本值}}

VerifyCodeServlet：

 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. 生成圖片* 2. 保存圖片上的文本到session域中* 3. 把圖片響應給客戶端*/ VerifyCode vc = new VerifyCode(); BufferedImage image = vc.getImage(); request.getSession().setAttribute("session_vcode", vc.getText());//保存圖片上的文本到session域VerifyCode.output(image, response.getOutputStream()); }}

LoginServlet:

 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 { /* * 校驗驗證碼* 1. 從session中獲取正確的驗證碼* 2. 從表單中獲取用戶填寫的驗證碼* 3. 進行比較！ * 4. 如果相同，向下運行，否則保存錯誤信息到request域，轉發到login.jsp */ String sessionCode = (String) request.getSession().getAttribute("session_vcode"); String paramCode = request.getParameter("verifyCode"); if(!paramCode.equalsIgnoreCase(sessionCode)) { request.setAttribute("msg", "驗證碼錯誤！"); request.getRequestDispatcher("/login.jsp").forward(request, response); return; } /* * 1. 獲取表單數據*/ // 處理中文問題request.setCharacterEncoding("utf-8"); // 獲取String username = request.getParameter("username"); String password = request.getParameter("password"); /* * 2. 校驗用戶名和密碼是否正確*/ if("itcast".equalsIgnoreCase(username)) {//登錄成功/* * 附加項：把用戶名保存到cookie中，發送給客戶端瀏覽器* 當再次打開login.jsp時，login.jsp中會讀取request中的cookie，把它顯示到用戶名文本框中*/ Cookie cookie = new Cookie("uname", username);//創建Cookie cookie.setMaxAge(60*60*24);//設置cookie命長為1天response.addCookie(cookie);//保存cookie /* * 3. 如果成功* > 保存用戶信息到session中* > 重定向到succ1.jsp */ HttpSession session = request.getSession();//獲取session session.setAttribute("username", username);//向session域中保存用戶名response.sendRedirect("/Test/succ1.jsp"); } else {//登錄失敗/* * 4. 如果失敗* > 保存錯誤信息到request域中* > 轉發到login.jsp */ request.setAttribute("msg", "用戶名或密碼錯誤!"); RequestDispatcher qr = request.getRequestDispatcher("/login.jsp");//得到轉發器qr.forward(request, response);//轉發} } }

login.jsp:

 <%@ 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><%-- 本頁面提供登錄表單，還要顯示錯誤信息--%><h1>登錄</h1><%/*讀取名為uname的Cookie!如果為空顯示：""如果不為空顯示：Cookie的值*/String uname = "";Cookie[] cs = request.getCookies();//獲取請求中所有的cookieif(cs != null) {// 如果存在cookie for(Cookie c : cs) {//循環遍歷所有的cookie if("uname".equals(c.getName())) {//查找名為uname的cookie uname = c.getValue();//獲取這個cookie的值，給uname這個變量} }}%><% String message = ""; String msg = (String)request.getAttribute("msg");//獲取request域中的名為msg的屬性if(msg != null) { message = msg; }%><font color="red"><b><%=message %> </b></font><form action="servlet/LoginServlet" method="post"> <%-- 把cookie中的用戶名顯示到用戶名文本框中--%> 用戶名：<input type="text" name="username" value="<%=uname%>"/><br/> 密碼：<input type="password" name="password"/><br/> 驗證碼：<input type="text" name="verifyCode" size="3"/> <img id="img" src="<%=basePath%>servlet/VerifyCodeServlet"/> <a href="javascript:_change()" rel="external nofollow" >換一張</a> <br/> <input type="submit" value="登錄"/></form> </body></html>

loginsuccess：

 <body><h1>succ1</h1><%String username = (String)session.getAttribute("username");if(username == null) { /* 1. 向request域中保存錯誤信息，轉發到login.jsp */ request.setAttribute("msg", "您還沒有登錄!請先登錄!"); request.getRequestDispatcher("/login.jsp").forward(request, response); return;}%>

歡迎歡迎，熱烈歡迎，歡迎<%=username %>領導指導工作！

 </body></html>

配置文件：

 <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>

建議：生成驗證碼的Servlet最好設置成不緩存，這樣就不用再頁面請求驗證碼圖片的時候加上時間戳了，加上時間戳就是欺騙瀏覽器防止瀏覽器讀取緩存裡的驗證碼圖片，而點擊換一張後沒反應。 這樣的不是很好的一點就是，每次點擊換一張，瀏覽器都會把新獲取的圖片緩存到本地，而在Servlet裡設置不緩存，就不會緩存到本地了。

總結

以上所述是小編給大家介紹的JAVA驗證碼工具實例代碼，希望對大家有所幫助，如果大家有任何疑問請給我留言，小編會及時回復大家的。在此也非常感謝大家對武林網網站的支持！