菜鳥學Java（六）——簡單驗證碼生成(Java版)

劉水鏡發表於2013-07-26
Java

驗證碼大家都知道，它的作用也不用我多說了吧。如果不太清楚請參見百度百科中的解釋，一般驗證碼的生成就是隨機產生字元（數字、字母或者漢字等），然後將這些生成的字元繪製成一張圖片，再在圖片上加上一些干擾元素，如各種線條之類的。好了廢話不多說一起往下看：



簡單的登入頁面（程式碼並不完整，只有驗證碼部分）
<%@ 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">
 //重新整理驗證碼的js函式  
function changeCode() {  
var imgNode = document.getElementById("vimg");                  

//重新載入驗證碼，達到重新整理的目的  
imgNode.src = "servlet/AuthImageServlet?t=" + Math.random();  // 防止瀏覽器快取的問題     
}    
    </script>
  </head>
  <body>
    <form action="checkServlet" method="post">
        <label>輸入驗證碼</label><br/>
        <input type="text" name="randomCode"/><img id="vimg"  title="點選更換" onclick="changeCode();" src="servlet/AuthImageServlet"><br/>
        <input type="submit" value="submit">
    </form>
  </body>
</html>

 

通過session.getAttribute("rand")，獲得生成的驗證碼，然後跟使用者輸入的進行比較，再根據比較結果做相應的處理。

通過servlet生成驗證碼： 

package com.util.servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class AuthImageServlet extends HttpServlet {

    private static final String CONTENT_TYPE = "text/html; charset=gb2312";   
    //設定字母的大小,大小   
    private Font mFont = new Font("Times New Roman", Font.PLAIN, 17);   
    public void init() throws ServletException   
    {   
        super.init();   
    }   
    Color getRandColor(int fc,int bc)   
    {   
        Random random = new Random();   
        if(fc>255) fc=255;   
        if(bc>255) bc=255;   
        int r=fc+random.nextInt(bc-fc);   
        int g=fc+random.nextInt(bc-fc);   
        int b=fc+random.nextInt(bc-fc);   
        return new Color(r,g,b);   
    }   
  
    public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException   
    {   
        response.setHeader("Pragma","No-cache");   
        response.setHeader("Cache-Control","no-cache");   
        response.setDateHeader("Expires", 0);   
        //表明生成的響應是圖片   
        response.setContentType("image/jpeg");   
           
        int width=100, height=18;   
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);   
           
        Graphics g = image.getGraphics();   
        Random random = new Random();   
        g.setColor(getRandColor(200,250));   
        g.fillRect(1, 1, width-1, height-1);   
        g.setColor(new Color(102,102,102));   
        g.drawRect(0, 0, width-1, height-1);   
        g.setFont(mFont);   
  
        g.setColor(getRandColor(160,200));   
  
        //畫隨機線   
        for (int i=0;i<155;i++)   
        {   
            int x = random.nextInt(width - 1);   
            int y = random.nextInt(height - 1);   
            int xl = random.nextInt(6) + 1;   
            int yl = random.nextInt(12) + 1;   
            g.drawLine(x,y,x + xl,y + yl);   
        }   
  
        //從另一方向畫隨機線   
        for (int i = 0;i < 70;i++)   
        {   
            int x = random.nextInt(width - 1);   
            int y = random.nextInt(height - 1);   
            int xl = random.nextInt(12) + 1;   
            int yl = random.nextInt(6) + 1;   
            g.drawLine(x,y,x - xl,y - yl);   
        }   
  
        //生成隨機數,並將隨機數字轉換為字母   
        String sRand="";   
        for (int i=0;i<6;i++)   
        {   
            int itmp = random.nextInt(26) + 65;   
            char ctmp = (char)itmp;   
            sRand += String.valueOf(ctmp);   
            g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));   
            g.drawString(String.valueOf(ctmp),15*i+10,16);   
        }   
  
        HttpSession session = request.getSession(true);   
        session.setAttribute("rand",sRand);   
        g.dispose();   
        ImageIO.write(image, "JPEG", response.getOutputStream());   
    }   
   
}

 



web.xml中的servlet配置資訊：

<?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>AuthImageServlet</servlet-name>
    <servlet-class>com.util.servlet.AuthImageServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>AuthImageServlet</servlet-name>
    <url-pattern>/servlet/AuthImageServlet</url-pattern>
  </servlet-mapping>
  
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

 


就這樣驗證碼的功能就實現了，很簡單、很實用。當然還有更加美觀，更加嚴密的方式，有興趣的朋友可以深入研究。這裡就跟大家分享一個比較簡單的方式。歡迎各位批評指正。


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