java驗證碼的用法

1、驗證碼1. 在項目中添加AuthImg.java（Servlet）2. 在web.xml中配置該Servlet<servlet><servlet-name>AuthImg</servlet-name><servlet-class>org.agency.servlet.AuthImg</servlet-class></servlet><servlet-mapping><servlet-name>AuthImg</servlet-name><url-pattern>/authIm

2、g.jpg</url-pattern></servlet-mapping>3. 頁面引用<script type="text/javascript">/驗證碼function changeImg()document.getElementById("authImg").src ="authImg.jpg?timpstamp=" + new Date().getTime();</script>驗證碼:<input type="text" name="cod

3、e" /><img src="authImg.jpg" id="authImg" /><input type="button" value="看不清，換一張" onclick="changeImg();" />4. 得到驗證碼！在AuthImg中它把驗證碼封裝到了session對象中名字是rand然后得到code和session中的rand比較這樣驗證碼的功能就完成了！AuthImg.java/* * 圖形驗證碼 hzl 09-11-29 */public

4、 class AuthImg extends HttpServlet private static final long serialVersionUID = 1L;/ 定義圖形驗證碼中繪制字符的字體private final Font mFont = new Font("Arial Black", Font.PLAIN, 16);/ 定義圖形驗證碼的大小private final int IMG_WIDTH = 100;private final int IMG_HEIGTH = 20;/ 定義一個獲取隨機顏色的方法private Color getRandColor(i

5、nt 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);/ 得到隨機顏色return new Color(r, g, b);/ 重寫service方法，生成對客戶端的響應public void service(HttpServletRequest

6、 request, HttpServletResponse response)throws ServletException, IOException / 設置禁止緩存response.setHeader("Pragma", "No-cache");response.setHeader("Cache-Control", "no-cache");response.setDateHeader("Expires", 0);response.setContentType("image/jpeg

7、");BufferedImage image = new BufferedImage(IMG_WIDTH, IMG_HEIGTH,BufferedImage.TYPE_INT_RGB);Graphics g = image.getGraphics();Random random = new Random();g.setColor(getRandColor(200, 250);/ 填充背景色g.fillRect(1, 1, IMG_WIDTH - 1, IMG_HEIGTH - 1);/ 為圖形驗證碼繪制邊框g.setColor(new Color(102, 102, 102);g.d

8、rawRect(0, 0, IMG_WIDTH - 1, IMG_HEIGTH - 1);g.setColor(getRandColor(160, 200);/ 生成隨機干擾線for (int i = 0; i < 80; i+) int x = random.nextInt(IMG_WIDTH - 1);int y = random.nextInt(IMG_HEIGTH - 1);int xl = random.nextInt(6) + 1;int yl = random.nextInt(12) + 1;g.drawLine(x, y, x + xl, y + yl);g.setCol

9、or(getRandColor(160, 200);/ 生成隨機干擾線for (int i = 0; i < 80; i+) int x = random.nextInt(IMG_WIDTH - 1);int y = random.nextInt(IMG_HEIGTH - 1);int xl = random.nextInt(12) + 1;int yl = random.nextInt(6) + 1;g.drawLine(x, y, x - xl, y - yl);/ 設置繪制字符的字體g.setFont(mFont);/ 用于保存系統(tǒng)生成的隨機字符串String sRand = &q

10、uot;"for (int i = 0; i < 6; i+) String tmp = getRandomChar();sRand += tmp;/ 獲取隨機顏色g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110);/ 在圖片上繪制系統(tǒng)生成的隨機字符g.drawString(tmp, 15 * i + 10, 15);/ 獲取HttpSesssion對象HttpSession session = request.getSession(t

11、rue);/ 將隨機字符串放入HttpSesssion對象中session.setAttribute("rand", sRand);g.dispose();/ 向輸出流中輸出圖片ImageIO.write(image, "JPEG", response.getOutputStream();/ 定義獲取隨機字符串方法private String getRandomChar() / 生成一個0、1、2的隨機數(shù)字int rand = (int) Math.round(Math.random() * 2);long itmp = 0;char ctmp = 'u0000'switch (rand) / 生成大寫字母case 1:itmp = Math.round(Math.random() * 25 + 65);ctmp = (char) itmp;return String.valueOf(ctmp);/