主要代码

public class Abc extends HttpServlet { private static final long serialVersionUID = 1L; public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } public Color getRandomColor(int fc,int bc){ Random random = new Random(); Color randomColor = null; if(fc>255) fc=255; if(bc>255) bc=255; //设置个0-255之间的随机颜色值 int r=fc+random.nextInt(bc-fc); int g=fc+random.nextInt(bc-fc); int b=fc+random.nextInt(bc-fc); randomColor = new Color(r,g,b); return randomColor;//返回具有指定红色、绿色和蓝色值的不透明的 sRGB 颜色 } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //禁止页面缓存 response.setHeader("Pragma", "No-cache"); response.setHeader("Cache-Control", "No-cache"); response.setDateHeader("Expires", 0); response.setContentType("image/jpeg"); //设置响应正文的MIME类型为图片 int width=60, height=20; /**创建一个位于缓存中的图像，宽度60，高度20 */ BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics g = image.getGraphics(); //获取用于处理图形上下文的对象，相当于画笔 Random random = new Random(); //创建生成随机数的对象 g.setColor(getRandomColor(200,250)); //设置图像的背景色 g.fillRect(0, 0, width, height); //画一个矩形 ，坐标（0，0），宽度60，高度20 g.setFont(new Font("Times New Roman",Font.PLAIN,18)); //设定字体格式 g.setColor(getRandomColor(160,200)); for(int i=0;i<130;i++){ //产生130条随机干扰线 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); //在图象的坐标（x,y）和坐标（x+x1,y+y1）之间画干扰线 } String strCode=""; for (int i=0;i<4;i++){ String strNumber=String.valueOf(random.nextInt(10)); //把随机数转换成String字符串 strCode=strCode+strNumber; //设置字体的颜色 g.setColor(new Color(15+random.nextInt(120),15+random.nextInt(120),15+random.nextInt(120))); g.drawString(strNumber,13*i+6,16); //将验证码依次画到图像上,坐标（x=13*i+6,y=16） } request.getSession().setAttribute("Code",strCode); //把验证码保存到Session中 g.dispose(); //释放此图像的上下文以及它使用的所有系统资源 ImageIO.write(image, "JPEG", response.getOutputStream()); //输出JPEG格式的图像 response.getOutputStream().flush(); //刷新输出流 response.getOutputStream().close(); //关闭输出流 } }