本文转自，http://www.bubuko.com/infodetail-720511.html
验证码的工具类， 这个jfinal自带的也有，但是下面这个和Jfinal自带的有一点点小的改动，（我用Jfinal自带的，在action中判断输入的验证码和系统随机生成的做对比的时候，出了问题。自带的类好像要用到MD5加密手动输入的验证码后才能判断，（这个我也不太清楚，只是我的感觉 -，- ！，真希望能有位好心人为我这样的菜鸟解答一下。））。呜，这个类也是在网上找的文章产考改的。。
package com.springscapital.console.ext.render;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.security.MessageDigest;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.Cookie;
import com.jfinal.core.Controller;
import com.jfinal.kit.StringKit;
import com.jfinal.render.Render;
/**
*
* @author Administrator
* 图形验证类
*/
public class MyCaptchaRender extends Render
{
private static final long serialVersionUID = -7599510915228560611L;
private static final String[] strArr = {"3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F", "G", "H", "J", "K", "M", "N", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y"};
private static String randomCodeKey = "JFINAL_JLHHWH_Key";
private static boolean caseInsensitive = true;
private int img_width = 85;
private int img_height = 20;
private int img_randNumber = 6;
public MyCaptchaRender() {
}
public MyCaptchaRender(String randomKey) {
if (StringKit.isBlank(randomKey))
throw new IllegalArgumentException("randomKey can not be blank");
randomCodeKey = randomKey;
}
public MyCaptchaRender(int width, int height, int count, boolean isCaseInsensitive) {
if(width <=0 || height <=0 || count <=0)
{
throw new IllegalArgumentException("Image width or height or count must be > 0");
}
this.img_width = width;
this.img_height = height;
this.img_randNumber = count;
caseInsensitive = isCaseInsensitive;
}
public MyCaptchaRender(String randomKey,int width, int height, int count, boolean isCaseInsensitive) {
if (StringKit.isBlank(randomKey))
throw new IllegalArgumentException("randomKey can not be blank");
randomCodeKey = randomKey;
if(width <=0 || height <=0 || count <=0)
{
throw new IllegalArgumentException("Image width or height or count must be > 0");
}
this.img_width = width;
this.img_height = height;
this.img_randNumber = count;
caseInsensitive = isCaseInsensitive;
}
public void render() {
BufferedImage image = new BufferedImage(img_width, img_height, BufferedImage.TYPE_INT_RGB);
String vCode = drawGraphic(image);
vCode = encrypt(vCode);
Cookie cookie = new Cookie(randomCodeKey, vCode);
cookie.setMaxAge(-1);
cookie.setPath("/");
response.addCookie(cookie);
response.setHeader("Pragma","no-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
response.setContentType("image/jpeg");
ServletOutputStream sos = null;
try {
sos = response.getOutputStream();
ImageIO.write(image, "jpeg",sos);
} catch (Exception e) {
throw new RuntimeException(e);
}
finally {
if (sos != null)
try {sos.close();} catch (IOException e) {e.printStackTrace();}
}
}
private String drawGraphic(BufferedImage image){
// 获取图形上下文
Graphics g = image.createGraphics();
// 生成随机类
Random random = new Random();
// 设定背景色
g.setColor(getRandColor(200, 250));
g.fillRect(0, 0, img_width, img_height);
// 设定字体
g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
g.setColor(getRandColor(160, 200));
for (int i = 0; i < 155; i++) {
int x = random.nextInt(img_width);
int y = random.nextInt(img_height);
int xl = random.nextInt(12);
int yl = random.nextInt(12);
g.drawLine(x, y, x + xl, y + yl);
}
// 取随机产生的认证码(img_randNumber位数字)
String sRand = "";
for (int i = 0; i < img_randNumber; i++) {
String rand = String.valueOf(strArr[random.nextInt(strArr.length)]);
sRand += rand;
// 将认证码显示到图象中
g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));
// 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
g.drawString(rand, 13 * i + 6, 16);
}
// 图象生效
g.dispose();
return sRand;
}
/*
* 给定范围获得随机颜色
*/
private 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);
}
private static final String encrypt(String srcStr) {
try {
String result = "";
MessageDigest md = MessageDigest.getInstance("MD5");
byte[] bytes = md.digest(srcStr.getBytes("utf-8"));
for(byte b:bytes){
String hex = Integer.toHexString(b&0xFF).toUpperCase();
result += ((hex.length() ==1 ) ? "0" : "") + hex;
}
return result;
} catch (Exception e) {
throw new RuntimeException(e);
}
}
public static boolean validate(Controller controller, String inputRandomCode) {
if (StringKit.isBlank(inputRandomCode))
return false;
try {
if(caseInsensitive)
inputRandomCode = inputRandomCode.toUpperCase();
inputRandomCode = encrypt(inputRandomCode);
return inputRandomCode.equals(controller.getCookie(randomCodeKey));
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
}
Action 中的代码 ：
package com.springscapital.console.site.controller;
import com.jfinal.core.Controller;
import com.springscapital.console.ext.render.MyCaptchaRender;
public class HomeController extends Controller{
public void index() {
render("/site/login.html");
}
//验证输入的和系统生成的验证码是否一样
public void login() {
String inputRandomCode = getPara("captcha");
boolean validate = MyCaptchaRender.validate(this, inputRandomCode);
System.out.println("CaptchaRender.validate=" + validate + ";inputRandomCode=" + inputRandomCode);
}
//生成图片
public void captcha(){
render(new MyCaptchaRender(60,22,4,true));
}
}
接下来就是页面中的代码了， 这个我也好纠结，本来想加个看不清换一张的按钮然后用ajax异步刷新验证码的，可惜没实现，页面中被我注释掉的代码就是我用的ajax，但是没搞出来，又有点小郁闷了，希望哪位大神看到了能为小弟解惑。
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<!-- <script type="text/javascript" src="${ctx!}/static/js/jquery-1.8.3.js"></script>
<script type="text/javascript">
$(function() {
$(".sumbit").click(
function() {
$.ajax( {
url : "${ctx!}/site/captcha",//发送请求的地址
data : {
account : $("#captcha").val()//发送到服务器的数据
},
error : function() {
alert("error: 网络异常请稍后再尝试!!!");//请求失败时弹出的信息
}
success : function(data) {//返回的信息展示出来
$(".hint").html(data);//请求成功时，调用的函数
}
});
});
});
</script> -->
</head>
<body>
<div class="main" align="center">
<form action="${ctx!}/site/login" method="post">
<table>
<tr>
<td>用户名：</td>
<td><input type="text" name="username"/></td>
</tr>
<tr>
<td>密 码：</td>
<td><input type="password" name="pwd"/></td>
</tr>
<tr>
<td><img src="${ctx!}/site/captcha"> </td>
<td>
<input type="text"id="captcha" name="captcha" value=""/>
<!-- <input class="sumbit" type="button" value="看不清换一张">
<input type=button value=刷新 onclick="location.reload()"> -->
</td>
</tr>
<tr>
<td> </td>
<td>
<INPUT TYPE="reset" name = "reset" value = "重 置">
<input type="submit" value="登陆"/>
</td>
</tr>
</table>
</form>
</div>
</body>
</html>