JavaWeb生成随机图片验证码（jsp + servlet）
在使用登陆或者注册功能的时候往往会有图片验证码的功能，那么如何实现图片验证码的功能呢？
1、生成长度可变的的随机字符，这里使用了A-Z 26位大写字母和0-9十位数字，如需其它字符可以自行添加。
public String GenerateCode(int length) {
int rand;
char code;
String randomCode = "";
Random random = new Random();
for(int i = 0;i < length;i++) {
rand = random.nextInt();
if(rand % 3 == 0) {
code = (char)('A' + (char)rand % 26);
}
else {
code = (char)('0' + (char)rand % 10);
}
randomCode += String.valueOf(code);
}
return randomCode;
}2、将随机生成的验证码字符写入，并添加噪点、设置验证码的背景颜色，字体样式等等。
//写入随机生成的验证码，并添加噪点
public BufferedImage Paint(String code ,int width ,int height) {
int mapWidth = width == 0 ? (int)(code.length() * 16) : width;
int mapHeight = height ==0 ? (int) 35 :height;
BufferedImage map = new BufferedImage(mapWidth,mapHeight,BufferedImage.TYPE_INT_RGB);
Graphics graph = map.getGraphics();
graph.setColor(Color.WHITE);
graph.fillRect(0, 0, mapWidth, mapHeight);
//设置字体样式
graph.setFont(new Font(Font.SANS_SERIF,Font.PLAIN,(int)(height*0.8)));
//添加噪点
Random random = new Random();
for(int i = 0;i < 50;i++) {
int x = random.nextInt(map.getWidth());
int y = random.nextInt(map.getHeight());
int rgb = GetRandomColor().getRGB();
map.setRGB(x, y, rgb);
}
//定义每个验证码字符颜色
Color[] c = { Color.BLACK, Color.RED, Color.BLUE, Color.GREEN, Color.ORANGE, Color.BLACK, Color.DARK_GRAY, Color.LIGHT_GRAY };
int fx = 0;
for(int i =0;i < code.length();i++) {
int x = random.nextInt(7);
graph.setColor(c[x]);
graph.drawString(code.charAt(i) + "", fx, (int)(height * 0.8));
fx+=(width / code.length()) * (Math.random() * 0.3 + 0.8);
}
graph.dispose();
return map;
}3、随机生成颜色，以供背景、噪点、字体颜色使用
//生成随机颜色
public Color GetRandomColor() {
Random random = new Random();
int r = random.nextInt(256);
int g = random.nextInt(256);
int b = random.nextInt(256);
return new Color(r, g, b);
}4、JSP 页面
<%@ page language="java" contentType="text/html; charset=UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<link href="css/base.css" rel="stylesheet" type="text/css">
<link href="css/module.css" rel="stylesheet" type="text/css">
<script src="scripts/jquery-1.10.2.min.js" type="text/javascript"></script>
<script type="text/javascript" language ="javascript">
$(function(){
//刷新验证码
$('#getCode').click(function () {
$("#getCode").attr("src", "GenerateCodeServlet?method=" + Math.random());
});
//登陆验证数据
$("#login").click(function(){
});
});
</script>
</head>
<body>
<div class="login">
<div class="login-main">
<div class="login-header">
<em>
</em>
<h4>通讯录</h4>
</div>
<form method="post">
<div class="login-area">
<div class="login-info">
<input autocomplete="off" type="text" id="account" name="account" placeholder="帐号" class="lgn-txt" />
</div>
<div class="login-info">
<input type="password" placeholder="密码" id="password" name="password" class="lgn-txt" />
</div>
<div>
<input type="text" placeholder="验证码" id="code" class="ipt-txt" style="width:60%; padding: 8px 5px;background-color: #FFF;border: 1px solid #DDD;border-radius: 3px;"/>
<a href="javascript:void(0)" style="width:25%"><img src="GenerateCodeServlet?method=image" id="getCode" /></a>
</div>
<div class="login-btn">
<input class="lgn-btn" type="button" value="立即登录" id="login" />
</div>
<div>没有账号？</div>
</div>
</form>
</div>
</div>
</body>
</html>5、Servlet，这里我并没有将随机生成的验证码存入 Session,使用该功能时候须将生成的验证码加入Session,然后才可以在登陆的时候进行验证用户输入的是否一致。
package pers.demo.servlet;
import java.io.IOException;
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 pers.demo.service.LoginService;
/**
* Servlet implementation class GenerateCodeServlet
*/
@WebServlet("/GenerateCodeServlet")
public class GenerateCodeServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public GenerateCodeServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
LoginService _service = new LoginService();
response.setContentType("image/jpeg");
response.setDateHeader("expries", -1);
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Pragma", "no-cache");
ImageIO.write(_service.Paint(_service.GenerateCode(4), 120, 39), "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);
}
}
最终实现的效果，点击验证码图片，会刷新验证码