Java验证码图片生成代码

public class VerifyCode {private int w=70;private int h=35;private Random r=new Random();//宋体，华文楷书，黑体，华文新魏，华文隶书，微软雅黑，楷体_GB2312,Times New Romanprivate String [] fontNames={"宋体","华文楷书","黑体","华文新魏","微软雅黑","华文隶书","楷体_GB2312","Times New Roman"};//可选的字符private String codes="23456789abcdefghijkmnopqrstuvwxyzABCDEFGHIJKLMNPQRSTUVWXYZ";//背景色private Color bgColor=new Color(255,255,255);//验证码上的文本private String text;//生成随机颜色private Color randomColor(){ int red=r.nextInt(150); int green=r.nextInt(150); int blue=r.nextInt(150); return new Color(red,green,blue);}//生成随机字体private Font randomFont(){int index=r.nextInt(fontNames.length);//获取下标String fontName=fontNames[index];//生成随机的字体名称int style=r.nextInt(4);//获取随机样式，0表示无样式，1表示粗体，2表示斜体，3表示粗体加斜体int size=r.nextInt(5)+24;//生成随机字号，24~28return new Font(fontName,style,size);}//画干扰线private void drawLine(BufferedImage image){int num=3;//一共画3条Graphics2D g2=(Graphics2D) image.getGraphics();for(int i=0;i<num;i++){//随机生成坐标，即4个值int x1=r.nextInt(w);int y1=r.nextInt(h);int x2=r.nextInt(w);int y2=r.nextInt(h);g2.setStroke(new BasicStroke(1.5F));//设置笔画的宽度  g2.setColor(Color.blue);//干扰线颜色  g2.drawLine(x1, y1, x2, y2);//画线}}//随机生成一个字符private char randomChar(){int index=r.nextInt(codes.length());return codes.charAt(index);}//创建BufferedImageprivate BufferedImage createImage(){BufferedImage image=new BufferedImage(w,h,BufferedImage.TYPE_INT_RGB);Graphics2D g2=(Graphics2D) image.getGraphics();g2.setColor(this.bgColor);g2.fillRect(0, 0, w, h);return image;}//外界调用这个方法得到验证码public BufferedImage getImage(){BufferedImage image=createImage();//创建图片缓冲区Graphics2D g2=(Graphics2D)image.getGraphics();//得到绘制环境StringBuilder sb=new StringBuilder();//用来装载生成的验证码文本//向图中画4个字符for(int i=0;i<4;i++){//循环4次String s=randomChar()+"";//随机生成一个字符sb.append(s);//把字母添加到sb中double x=i*1.0*w/4;//设置当前字符的x轴坐标g2.setFont(randomFont());//设置随机字体g2.setColor(randomColor());//设置随机颜色g2.drawString(s, (int)x, h-5);}this.text=sb.toString();//把生成的字符串赋给了this.textdrawLine(image);//添加干扰线return image;}//返回验证码图片上面的文本public String getText(){return text;}//保存图片到指定的输出流public static void output(BufferedImage image,OutputStream out) throws IOException{ImageIO.write(image, "JPEG", out);}}

<form action="/test/LoginServlet" method="post">   用户名：<input type="text" name="username" value="<%=uname %>"><br>   密 码：<input type="password" name="password"><br>   验证码：<input type="text" name="verifyCode">  <img id="img" src="/test/VerifyCodeServlet">  <a href="JavaScript:_change()" rel="external nofollow" >看不清换一张</a><br>  <input type="submit" value="登录"> </form>

   <script type="text/javascript">      function _change(){        /**        *1.得到image图片        *2.修改其src为/test/VerifyCodeServlet         */        var imgEle=document.getElementById("img");        imgEle.src="/test/VerifyCodeServlet?a="+new Date().getTime();      }  </script>

public class VerifyCodeServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {/** 1.生成图片* 2.保存图片上的文本到session域中* 3.把图片响应给客户端*/VerifyCode vc=new VerifyCode();BufferedImage image=vc.getImage();//保存图片上的文本到session域request.getSession().setAttribute("session_code", vc.getText());VerifyCode.output(image, response.getOutputStream());  }}

public class LoginServlet extends HttpServlet {public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {/** 校验验证码* 1.从session中获取正取的验证码* 2.从表单中获取用户填写的验证码* 3.进行比较* 4.如果相同，向下运行，否则保存错误信息到request域，转发到login.jsp*/String sessionCode=(String)                     request.getSession().getAttribute("session_code");//获得的验证码里面对应的文本内容String paramCode=request.getParameter("verifyCode");//用户输入文本框里面的内容if(!paramCode.equalsIgnoreCase(sessionCode)){request.setAttribute("msg", "验证码错误！");request.getRequestDispatcher("/login.jsp").forward(request, response);//打回到登录界面。return;//返回，不继续执行下面的语句。}}}