Servlet生成随机验证码
2007-06-07 14:21
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Servlet部分: package servlet; import java.io.*; import java.util.*; import javax.servlet.*; import javax.servlet.http.*; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import javax.imageio.ImageIO; import java.awt.image.BufferedImage; public class CreateImage extends HttpServlet { String width; String height; public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //生成4位数字随机数 int randnumber=(int)Math.floor(Math.random()*10000); String rand=String.valueOf(randnumber); switch(rand.length()){ case 1: rand = "000"+rand; break; case 2: rand = "00"+rand; break; case 3: rand = "0"+rand; break; case 4: break; } //生成图象 try { response.setContentType("image/jpeg"); response.setHeader("Pragma", "No-cache"); response.setHeader("Cache-Control", "no-cache"); response.setDateHeader("Expires", 0); BufferedImage image = new BufferedImage(Integer.parseInt(width), Integer.parseInt(height), BufferedImage.TYPE_INT_RGB); // 获取图形上下文 Graphics g = image.getGraphics(); // 设定背景色 g.setColor(Color.white); g.fillRect(0, 0, Integer.parseInt(width), Integer.parseInt(height)); // 将认证码显示到图象中 g.setColor(Color.black); g.setFont(new Font("Times New Roman", Font.PLAIN, 18)); g.drawString(rand, 15, 16); // 随机产生88个干扰点,使图象中的认证码不易被其它程序探测到 Random random = new Random(); for (int i = 0; i < 88; i++) { int x = random.nextInt(Integer.parseInt(width)); int y = random.nextInt(Integer.parseInt(height)); g.drawLine(x, y, x, y); } // 图象生效 g.dispose(); ServletOutputStream responseOutputStream = response.getOutputStream(); // 输出图象到页面 ImageIO.write(image, "JPEG", responseOutputStream); // 以下关闭输入流! responseOutputStream.flush(); responseOutputStream.close(); //随机数字放到session request.getSession().setAttribute("randNumber", rand); } catch (Exception e) { e.printStackTrace(); } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } /** * @function: 初试化方法,得到xml配置文件中数值 */ public void init() throws ServletException { width=getInitParameter("width"); height=getInitParameter("height"); } } xml配置部分: <!-- 随即生成验证数字 --> <servlet> <servlet-name>picShow</servlet-name> <servlet-class>servlet.CreateImage</servlet-class> <init-param> <param-name>width</param-name> <param-value>60</param-value> </init-param> <init-param> <param-name>height</param-name> <param-value>22</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>picShow</servlet-name> <url-pattern>/imageShow</url-pattern> </servlet-mapping> 页面调用部分: <img src="imageShow" /> |
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