Java 验证码实践

ValidateCode.java

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Bufferprivate BufferedImage buffImg=null;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' };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fontHeight = height - 2;//字体的高度codeY = height - 4;// 图像bufferbuffImg = 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g.setFont(new Font("Helvetica", Font.BOLD,20));for (int i = 0; i < lineCount; i++) {int xs = random.nextInt(width);int ys = random.nextInt(height);int xe = xs+random.nextInt(width/8);int ye = ys+random.nextInt(height/8);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;}}

ValidateCodeServlet.java

public class ValidateCodeServlet extends HttpServlet {    private static final long serialVersionUID = 1L;    /**     * spring中注册的缓存服务名     */    public static final String CACHE_SERVICE_BEAN_NAME = "cacheService";    @Override    protected void doGet(HttpServletRequest reqeust,                         HttpServletResponse response) throws ServletException, IOException {        HttpSession session = reqeust.getSession();        ValidateCode vCode = new ValidateCode(120, 40, 5, 50);        String code = new String(vCode.getCode().getBytes("ISO8859-1"));        // 验证码进缓存--- 另一种思路：验证码存在session中  session.setAttribute方法        CacheService cacheService = SpringLocator.getBean(CACHE_SERVICE_BEAN_NAME);        if (null == cacheService) {            return;        }        cacheService.add(new CacheKey(CacheKeyNamespace.OBJ_VALIDATE_CODE, session.getId()), code.toLowerCase().trim());        // 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.setHeader("Captcha", code);        response.setDateHeader("Expires", 0);        vCode.write(response.getOutputStream());    }}

web.xml

<servlet><servlet-name>ValidateCodeServlet</servlet-name><servlet-class>包路径.ValidateCodeServlet</servlet-class></servlet>

<servlet-mapping><servlet-name>ValidateCodeServlet</servlet-name><url-pattern>/validateCode</url-pattern></servlet-mapping>

前端页面

<img id="identifying-code-img"  src="validateCode" onclick="changeIdentifyingCode(jQuery(this))">...function changeIdentifyingCode(element) {    element.attr("src", "validateCode?"+Math.random());}