利用java实现一个web页面校验验证码功能

import javax.imageio.ImageIO; 
import java.awt.*; 
import java.awt.image.BufferedImage; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.OutputStream; 
import java.util.Date; 
import java.util.Random; 
 
/** 
 * 验证码生成器 
 * 
 * @author 
 */ 
public class ValidateCode { 
 // 图片的宽度。 
 private int width = 160; 
 // 图片的高度。 
 private int height = 40; 
 // 验证码字符个数 
 private int codeCount = 5; 
 // 验证码干扰线数 
 private int lineCount = 150; 
 // 验证码 
 private String code = null; 
 // 验证码图片Buffer 
 private BufferedImage buffImg = null; 
 
 // 验证码范围,去掉0(数字)和O(拼音)容易混淆的(小写的1和L也可以去掉,大写不用了) 
 private char[] codeSequence = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 
   'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 
   'X', 'Y', 'Z', '1', '2', '3', '4', '5', '6', '7', '8', '9'}; 
 
 /** 
  * 默认构造函数,设置默认参数 
  */ 
 public ValidateCode() { 
  this.createCode(); 
 } 
 
 /** 
  * @param width 图片宽 
  * @param height 图片高 
  */ 
 public ValidateCode(int width, int height) { 
  this.width = width; 
  this.height = height; 
  this.createCode(); 
 } 
 
 /** 
  * @param width  图片宽 
  * @param height 图片高 
  * @param codeCount 字符个数 
  * @param lineCount 干扰线条数 
  */ 
 public ValidateCode(int width, int height, int codeCount, int lineCount) { 
  this.width = width; 
  this.height = height; 
  this.codeCount = codeCount; 
  this.lineCount = lineCount; 
  this.createCode(); 
 } 
 
 public void createCode() { 
  int x = 0, fontHeight = 0, codeY = 0; 
  int red = 0, green = 0, blue = 0; 
 
  x = width / (codeCount + 2);//每个字符的宽度(左右各空出一个字符) 
  fontHeight = height - 2;//字体的高度 
  codeY = height - 4; 
 
  // 图像buffer 
  buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); 
  Graphics2D g = buffImg.createGraphics(); 
  // 生成随机数 
  Random random = new Random(); 
  // 将图像填充为白色 
  g.setColor(Color.WHITE); 
  g.fillRect(0, 0, width, height); 
  // 创建字体,可以修改为其它的 
  Font font = new Font("Fixedsys", Font.PLAIN, fontHeight); 
//  Font font = new Font("Times New Roman", Font.ROMAN_BASELINE, fontHeight); 
  g.setFont(font); 
 
  for (int i = 0; i < lineCount; i++) { 
   // 设置随机开始和结束坐标 
   int xs = random.nextInt(width);//x坐标开始 
   int ys = random.nextInt(height);//y坐标开始 
   int xe = xs + random.nextInt(width / 8);//x坐标结束 
   int ye = ys + random.nextInt(height / 8);//y坐标结束 
 
   // 产生随机的颜色值，让输出的每个干扰线的颜色值都将不同。 
   red = random.nextInt(255); 
   green = random.nextInt(255); 
   blue = random.nextInt(255); 
   g.setColor(new Color(red, green, blue)); 
   g.drawLine(xs, ys, xe, ye); 
  } 
 
  // randomCode记录随机产生的验证码 
  StringBuffer randomCode = new StringBuffer(); 
  // 随机产生codeCount个字符的验证码。 
  for (int i = 0; i < codeCount; i++) { 
   String strRand = String.valueOf(codeSequence[random.nextInt(codeSequence.length)]); 
   // 产生随机的颜色值，让输出的每个字符的颜色值都将不同。 
   red = random.nextInt(255); 
   green = random.nextInt(255); 
   blue = random.nextInt(255); 
   g.setColor(new Color(red, green, blue)); 
   g.drawString(strRand, (i + 1) * x, codeY); 
   // 将产生的四个随机数组合在一起。 
   randomCode.append(strRand); 
  } 
  // 将四位数字的验证码保存到Session中。 
  code = randomCode.toString(); 
 } 
 
 public void write(String path) throws IOException { 
  OutputStream sos = new FileOutputStream(path); 
  this.write(sos); 
 } 
 
 public void write(OutputStream sos) throws IOException { 
  ImageIO.write(buffImg, "png", sos); 
  sos.close(); 
 } 
 
 public BufferedImage getBuffImg() { 
  return buffImg; 
 } 
 
 public String getCode() { 
  return code; 
 } 
 
 /** 
  * 测试函数,默认生成到d盘 
  * @param args 
  */ 
 public static void main(String[] args) { 
  ValidateCode vCode = new ValidateCode(160,40,5,150); 
  try { 
   String path="D:/"+new Date().getTime()+".png"; 
   System.out.println(vCode.getCode()+" >"+path); 
   vCode.write(path); 
  } catch (IOException e) { 
   e.printStackTrace(); 
  } 
 } 
} 

// 刷新图片 
  function changeImg() { 
   var imgSrc = $("#imgObj"); 
   var url = imgSrc.attr("src"); 
   imgSrc.attr("src", changeUrl(url)); 
  } 
  //为了使每次生成图片不一致，即不让浏览器读缓存，所以需要加上时间戳 
  function changeUrl(url) { 
   var timestamp = (new Date()).valueOf(); 
   var index = url.indexOf("?"); 
   console.log(index); 
   if (index > 0) { 
    url = url.substring(0, url.indexOf("?")); 
   } 
   console.log(url); 
   if ((url.indexOf("&") > 0)) { 
    url = url + "×tamp=" + timestamp; 
    console.log(url); 
   } else { 
    url = url + "?timestamp=" + timestamp; 
    console.log(url); 
    } 
   return url; 
  } 

/** 
 * 响应验证码页面 
 * @return 
 */ 
@RequestMapping(value="/validateCode") 
public String validateCode(HttpServletRequest request,HttpServletResponse response) throws Exception{ 
 // 设置响应的类型格式为图片格式 
 response.setContentType("image/jpeg"); 
 //禁止图像缓存。 
 response.setHeader("Pragma", "no-cache"); 
 response.setHeader("Cache-Control", "no-cache"); 
 response.setDateHeader("Expires", 0); 
 
 HttpSession session = request.getSession(); 
 
 ValidateCode vCode = new ValidateCode(120,40,5,100); 
 session.setAttribute("code", vCode.getCode()); 
 vCode.write(response.getOutputStream()); 
 return null; 
} 

String code = request.getParameter("code"); 
HttpSession session = request.getSession(); 
String sessionCode = (String) session.getAttribute("code"); 
if (!StringUtils.equalsIgnoreCase(code, sessionCode)) { //忽略验证码大小写 
 throw new RuntimeException("验证码对应不上code=" + code + " sessionCode=" + sessionCode); 
}