標籤：提交 驗證 control mit 隨機 omv 上進 session welcome
為了防止使用者惡意,或者使用軟體外掛提交一些內容,就得用驗證碼來阻止,雖然這個會影響使用者體驗,但為了避免一些問題很多網站都使用了驗證碼;今天下午參考文檔弄了一個驗證碼,這裡分享一下;這是一個web工程,首先是頁面,這裡只是一個顯示驗證碼頁面index.jsp,使用預設產生的就可以了,表單沒有做提交,如下
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <title>驗證碼</title> <script type="text/javascript"> function refresh(obj) { obj.src = "imageServlet?"+Math.random(); } </script> </head> <body> <form action="checkServlet" method="post"> <label>輸入驗證碼</label><br/> <input type="text" name="randomCode"/><img title="點擊更換" onclick="javascript:refresh(this);" src="imageServlet"><br/> <input type="submit" value="submit"> </form> </body></html>
下面是後台代碼,這裡是一個Servlet,不要忘記在web.xml中配置請求url
package com.wf.web;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 ImageServlet extends HttpServlet { private static final long serialVersionUID = 1L; public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("image/jpeg");//設定相應類型,告訴瀏覽器輸出的內容為圖片 response.setHeader("Pragma", "No-cache");//設定回應標頭資訊，告訴瀏覽器不要緩衝此內容 response.setHeader("Cache-Control", "no-cache"); response.setDateHeader("Expire", 0); RandomValidateCode randomValidateCode = new RandomValidateCode(); try { randomValidateCode.getRandcode(request, response);//輸出圖片方法 } catch (Exception e) { e.printStackTrace(); } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); }}
這個類是產生驗證碼的方法,如下
package com.wf.web;import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.util.Random;import javax.imageio.ImageIO;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;public class RandomValidateCode { public static final String RANDOMCODEKEY = "RANDOMVALIDATECODEKEY";//放到session中的key private Random random = new Random(); private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//隨機產生的字串 private int width = 80;//圖片寬 private int height = 26;//圖片高 private int lineSize = 40;//幹擾線數量 private int stringNum = 4;//隨機產生字元數量 /* * 獲得字型 */ private Font getFont(){ return new Font("Fixedsys",Font.CENTER_BASELINE,18); } /* * 獲得顏色 */ private Color getRandColor(int fc,int bc){ if(fc > 255) fc = 255; if(bc > 255) bc = 255; int r = fc + random.nextInt(bc-fc-16); int g = fc + random.nextInt(bc-fc-14); int b = fc + random.nextInt(bc-fc-18); return new Color(r,g,b); } /** * 產生隨機圖片 */ public void getRandcode(HttpServletRequest request, HttpServletResponse response) { HttpSession session = request.getSession(); //BufferedImage類是具有緩衝區的Image類,Image類是用於描述映像資訊的類 BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR); Graphics g = image.getGraphics();//產生Image對象的Graphics對象,改對象可以在映像上進行各種繪製操作 g.fillRect(0, 0, width, height); g.setFont(new Font("Times New Roman",Font.ROMAN_BASELINE,18)); g.setColor(getRandColor(110, 133)); //繪製幹擾線 for(int i=0;i<=lineSize;i++){ drowLine(g); } //繪製隨機字元 String randomString = ""; for(int i=1;i<=stringNum;i++){ randomString=drowString(g,randomString,i); } session.removeAttribute(RANDOMCODEKEY); session.setAttribute(RANDOMCODEKEY, randomString); System.out.println(randomString); g.dispose(); try { ImageIO.write(image, "JPEG", response.getOutputStream());//將記憶體中的圖片通過流動形式輸出到用戶端 } catch (Exception e) { e.printStackTrace(); } } /* * 繪製字串 */ private String drowString(Graphics g,String randomString,int i){ g.setFont(getFont()); g.setColor(new Color(random.nextInt(101),random.nextInt(111),random.nextInt(121))); String rand = String.valueOf(getRandomString(random.nextInt(randString.length()))); randomString +=rand; g.translate(random.nextInt(3), random.nextInt(3)); g.drawString(rand, 13*i, 16); return randomString; } /* * 繪製幹擾線 */ private void drowLine(Graphics g){ int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(13); int yl = random.nextInt(15); g.drawLine(x, y, x+xl, y+yl); } /* * 擷取隨機的字元 */ public String getRandomString(int num){ return String.valueOf(randString.charAt(num)); }}
web.xml檔案
<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <servlet> <servlet-name>ImageServlet</servlet-name> <servlet-class>com.wf.web.ImageServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>ImageServlet</servlet-name> <url-pattern>/imageServlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list></web-app>
就這麼多,驗證碼是儲存在session中的,或者cookie也行,但都要必須及時清除
java產生驗證碼
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