生成图片验证码

一、--------------------------------------------------------------------------login.jsp----------------------------

<p class="login-input login-input-2">

<span class="glyphicon"><i class="glyphicon glyphicon-option-horizontal icon-i"></i></span>

<input type="text" name="j_captcha" class="input-small" id="yanzheng" placeholder="请输入验证码">

</p>

<span style="margin-left:5px" class="validatecode">

    <a href="#" onclick="refreshCaptcha();">

        <img id="randomcode_img" src="/validatecode" title="点击换一张" />

    </a>

</span>

function refreshCaptcha() {

    $('#randomcode_img').hide().attr('src','/validatecode?' +         Math.floor(Math.random()*100)).fadeIn();

}

二、--------------------------------------------------------------------------controller------------------------------

@RequestMapping(value = "/validatecode", method = RequestMethod.GET)

public String generateCaptchaImage() {

return "/admin/auth/validatecode";

}

三、--------------------------------------------------------------------------validatecode.jsp-------------------

<%@ page language ="java" contentType="text/html; charset=UTF-8"

pageEncoding="UTF-8"%>

<%@ page import ="java.util.Random"%>

<%@ page import ="java.io.OutputStream"%>

<%@ page import ="java.awt.Color"%>

<%@ page import ="java.awt.Font"%>

<%@ page import ="java.awt.Graphics"%>

<%@ page import ="java.awt.image.BufferedImage"%>

<%@ page import ="javax.imageio.ImageIO"%>

<%@ page import="com.google.code.kaptcha.Constants" %>

<%

int width = 60;

int height = 32;

//create the image

BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

Graphics g = image.getGraphics();

// set the background color

g.setColor(new Color(0xeeeeee));

g.fillRect(0, 0, width, height);

// draw the border

g.setColor(Color.gray);

g.drawRect(0, 0, width - 1, height - 1);

// create a random instance to generate the codes

Random rdm = new Random();

String hash1 = Integer.toHexString(rdm.nextInt());

// System.out.print(hash1);

// make some confusion

for (int i = 0; i < 50; i++) {

int x = rdm.nextInt(width);

int y = rdm.nextInt(height);

g.drawOval(x, y, 0, 0);

}

// generate a random code

String capstr = hash1.substring(0, 4);

//将生成的验证码存入session

session.setAttribute(Constants.KAPTCHA_SESSION_KEY, capstr);

g.setColor(new Color(0, 153, 255));

g.setFont(new Font("Arial", Font.BOLD, 22));

g.drawString(capstr, 8, 24);

g.dispose();

//输出图片

response.setContentType( "image/jpeg");

out.clear();

out = pageContext.pushBody();

OutputStream strm = response.getOutputStream();

ImageIO.write(image, "jpeg", strm);

strm.close();

%>