html页面
<img align="absbottom" src="/yzm" width="66" height="22" />
web.xml配置servlet
<servlet> <servlet-name>yzm</servlet-name> <servlet-class>com.fun.yzm</servlet-class> </servlet> <servlet-mapping> <servlet-name>yzm</servlet-name> <url-pattern>/yzm</url-pattern> </servlet-mapping>
java代码
import java.io.*;import javax.servlet.*;import javax.servlet.http.*;import java.awt.*;import java.awt.image.*;import java.util.*;import javax.imageio.*;/**** @author http://www.tot.name* @version*/ public class yzm extends HttpServlet {/** Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.* @param request servlet request* @param response servlet response*/protected void processRequest(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException { response.setContentType("image/jpeg;charset=GB2312"); response.setHeader("Pragma","No-cache"); response.setHeader("Cache-Control","no-cache"); response.setDateHeader("Expires", 0); HttpSession session=request.getSession(); // 在内存中创建图象 int width=60, height=20; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // 获取图形上下文 Graphics g = image.getGraphics(); //生成随机类 Random random = new Random(); // 设定背景色 g.setColor(getRandColor(200,250)); g.fillRect(0, 0, width, height); //设定字体 g.setFont(new Font("Times New Roman",Font.PLAIN,18)); //画边框 //g.setColor(new Color()); //g.drawRect(0,0,width-1,height-1); // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到 g.setColor(getRandColor(160,200)); for (int i=0;i<155;i++) { int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(12); int yl = random.nextInt(12); g.drawLine(x,y,x+xl,y+yl); }// String str = "妈妈说验证用中文最好";// String[] strs = str.split(""); // 取随机产生的认证码(4位数字) String sRand=""; for (int i=0;i<4;i++){ String rand=String.valueOf(random.nextInt(10));// String rand = strs[random.nextInt(10)]; sRand+=rand; // 将认证码显示到图象中 g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成 g.drawString(rand,13*i+6,16); } // 将认证码存入SESSION session.setAttribute("rand",sRand); // 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();}Color getRandColor(int fc,int bc){//给定范围获得随机颜色 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); return new Color(r,g,b);}// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">/** Handles the HTTP <code>GET</code> method.* @param request servlet request* @param response servlet response*/protected void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException { processRequest(request, response);}/** Handles the HTTP <code>POST</code> method.* @param request servlet request* @param response servlet response*/protected void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException { processRequest(request, response);}/** Returns a short description of the servlet.*/public String getServletInfo() { return "Short description";}// </editor-fold>}
