这篇文章会从前台页面到后台实现完整的讲解，下面跟着小编一起来看看。
1、前台的代码，image.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>获取图片验证码</title>
<script type="text/javascript" src="${pageContext.request.contextPath }/static/js/jquery-1.10.2.min.js"></script>
</head>
<body>
<form action="##" method='post'>
<input type="hidden" id="userId" name="userId" value="">
<div class="form-group">
<div class="email controls">
<input type="text" name='loginName' id="loginName" placeholder="用户名" value="" class='form-control'/>
</div>
</div>
<div class="form-group">
<div class="pw controls">
<input type="password" autocomplete="off" id="pwd" name="pwd" placeholder="密码" class='form-control'/>
</div>
</div>
<div class="form-group">
<div class="email controls">
<input id="validateCode" onblur="checkImg(this.value)" name="validateCode" type="text" class="form-control" placeholder="输入验证码"/>
</div>
<span class="y_yzimg"><img id="codeValidateImg" onClick="javascript:flushValidateCode();"/></span>
<p class="y_change"><a href="javascript:flushValidateCode();" >换一张</a></p>
</div>
<div class="form-group">
<span class="text-danger"></span>
</div>
<div class="submit">
<div class="remember">
<input type="checkbox" name="remember" value="1" class='icheck-me' data-skin="square" data-color="blue" id="remember">
<label for="remember">记住我</label>
</div>
<input type="button" value="登录" onclick="javascript:submitForm();" class='btn btn-primary'>
</div>
</form>
<script type="text/javascript">
$(document).ready(function() {
flushValidateCode();//进入页面就刷新生成验证码
});
/* 刷新生成验证码 */
function flushValidateCode(){
var validateImgObject = document.getElementById("codeValidateImg");
validateImgObject.src = "${pageContext.request.contextPath }/getSysManageLoginCode?time=" + new Date();
}
/*校验验证码输入是否正确*/
function checkImg(code){
var url = "${pageContext.request.contextPath}/checkimagecode";
$.get(url,{"validateCode":code},function(data){
if(data=="ok"){
alert("ok!")
}else{
alert("error!")
flushValidateCode();
}
})
}
</script>
</body>
</html>
2、后台代码ImageGenController.java
package com.dufyun.springmvc.web.controller;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Controller;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import com.dufy.javaweb.test.RandomValidateCode;
@Controller
public class ImageGenController {
@RequestMapping(value="/toImg")
public String toImg(){
return "image/image";
}
//登录获取验证码
@RequestMapping("/getSysManageLoginCode")
@ResponseBody
public String getSysManageLoginCode(HttpServletResponse response,
HttpServletRequest request) {
response.setContentType("image/jpeg");// 设置相应类型,告诉浏览器输出的内容为图片
response.setHeader("Pragma", "No-cache");// 设置响应头信息，告诉浏览器不要缓存此内容
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Set-Cookie", "name=value; HttpOnly");//设置HttpOnly属性,防止Xss攻击
response.setDateHeader("Expire", 0);
RandomValidateCode randomValidateCode = new RandomValidateCode();
try {
randomValidateCode.getRandcode(request, response,"imagecode");// 输出图片方法
} catch (Exception e) {
e.printStackTrace();
}
return "";
}
//验证码验证
@RequestMapping(value = "/checkimagecode")
@ResponseBody
public String checkTcode(HttpServletRequest request,HttpServletResponse response) {
String validateCode = request.getParameter("validateCode");
String code = null;
//1:获取cookie里面的验证码信息
Cookie[] cookies = request.getCookies();
for (Cookie cookie : cookies) {
if ("imagecode".equals(cookie.getName())) {
code = cookie.getValue();
break;
}
}
//1:获取session验证码的信息
//String code1 = (String) request.getSession().getAttribute("");
//2:判断验证码是否正确
if(!StringUtils.isEmpty(validateCode) && validateCode.equals(code)){
return "ok";
}
return "error";
//这里我没有进行字母大小模糊的验证处理，感兴趣的你可以去试一下！
}
}
3、生成验证码的工具类RandomValidateCode.java
package com.dufy.javaweb.test;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class RandomValidateCode {
private Random random = new Random();
private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";// 随机产生的字符串
private int width = 80;// 图片宽
private int height = 26;// 图片高
private int lineSize = 40;// 干扰线数量
private int stringNum = 4;// 随机产生字符数量
/*
* 获得字体
*/
private Font getFont() {
return new Font("Fixedsys", Font.CENTER_BASELINE, 18);
}
/*
* 获得颜色
*/
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);
}
/*
* 绘制字符串
*/
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;
}
/*
* 绘制干扰线
*/
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);
}
/*
* 获取随机的字符
*/
public String getRandomString(int num) {
return String.valueOf(randString.charAt(num));
}
/**
* 生成随机图片
*/
public void getRandcode(HttpServletRequest request,HttpServletResponse response,String key) {
// BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_BGR);
Graphics g = image.getGraphics();// 产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
g.fillRect(0, 0, width, height);
g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 18));
g.setColor(getRandColor(110, 133));
// 绘制干扰线
for (int i = 0; i <= lineSize; i++) {
drowLine(g);
}
// 绘制随机字符
String randomString = "";
for (int i = 1; i <= stringNum; i++) {
randomString = drowString(g, randomString, i);
}
//1：将随机生成的验证码放入Cookie中
Cookie cookie = new Cookie(key,randomString);
response.addCookie(cookie);
//2：将随机生成的验证码放入session中
String sessionid = request.getSession().getId();
request.getSession().setAttribute(sessionid+key, randomString);
System.out.println("*************" + randomString);
//总结：这两种方式都是很好，
//（1）：使用cookie的方式，将验证码发送到前台浏览器，不安全！不建议使用。
//（2）：使用session的方式，虽然能解决验证码不发送到浏览器，安全性较高了，但是如果用户量太大，这样的存储方式会对服务器造成压力，影响服务器的性能。不建议使用。
//这里暂时实现用这种方式，好的办法是，在项目中使用的缓存，将生成的验证码存放到缓存中，设置失效时间，这样既可以实现安全性也能减轻服务器的压力。
g.dispose();
try {
ByteArrayOutputStream tmp = new ByteArrayOutputStream();
ImageIO.write(image, "png", tmp);
tmp.close();
Integer contentLength = tmp.size();
response.setHeader("content-length", contentLength + "");
response.getOutputStream().write(tmp.toByteArray());// 将内存中的图片通过流动形式输出到客户端
} catch (Exception e) {
e.printStackTrace();
}finally{
try {
response.getOutputStream().flush();
response.getOutputStream().close();
} catch (Exception e2) {
e2.printStackTrace();
}
}
}
}
4、总结
本文的内容到这就结束了，如果对里面的地方有不懂的地方，可以留言讨论。希望本文的内容对大家的学习工作能有所帮助。