java后台验证码生成的实现方法

/*验证码输入框*/
 
<input class="verifyInput"  name="verifyInput" placeholder="请输入验证码">   
 
 
/*验证码图片*/
 
<img class="verifyCode" onclick="changeCode()" src="getVerifyCode">
 
//src的getVerifyCode是后台访问地址；项目为SSM框架。
 
 
/*点击刷新验证码*/
 
function changeCode(){
 
         var src = " getVerifyCode?"+new Date().getTime(); //加时间戳，防止浏览器利用缓存
 
    $('.verifyCode').attr("src",src);                  //jQuery写法
 
}

/* 获取验证码图片*/
 
         @RequestMapping("/getVerifyCode ")
 
         public void getVerificationCode(HttpServletResponse response,HttpServletRequest request) {
 
                   try {
 
                            int width=200;
 
                            int height=69;
 
         BufferedImage verifyImg=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
 
//生成对应宽高的初始图片
 
                            String randomText = VerifyCode.drawRandomText(width,height,verifyImg);
 
//单独的一个类方法，出于代码复用考虑，进行了封装。
 
//功能是生成验证码字符并加上噪点，干扰线，返回值为验证码字符                   
 
request.getSession().setAttribute("verifyCode", randomText);
 
                   response.setContentType("image/png");//必须设置响应内容类型为图片，否则前台不识别
 
                 OutputStream os = response.getOutputStream(); //获取文件输出流    
 
                 ImageIO.write(verifyImg,"png",os);//输出图片流
 
                 os.flush();
 
                 os.close();//关闭流
 
                   } catch (IOException e) {
 
                            this.logger.error(e.getMessage());
 
                            e.printStackTrace();
 
                   }
 
         }

/*对图片进行处理的类和方法*/
 
public class VerifyCode {  
 
    public static  String drawRandomText(int width,int height,BufferedImage verifyImg) {
             Graphics2D graphics = (Graphics2D)verifyImg.getGraphics();
             graphics.setColor(Color.WHITE);//设置画笔颜色-验证码背景色
             graphics.fillRect(0, 0, width, height);//填充背景
        graphics.setFont(new Font("微软雅黑", Font.BOLD, 40));
        //数字和字母的组合
String baseNumLetter= = "123456789abcdefghijklmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ";
 
        StringBuffer sBuffer = new StringBuffer();
        int x = 10;  //旋转原点的 x 坐标
        String ch = "";
        Random random = new Random();
        for(int i = 0;i < 4;i++){
                 graphics.setColor(getRandomColor());
            //设置字体旋转角度
            int degree = random.nextInt() % 30;  //角度小于30度
            int dot = random.nextInt(baseNumLetter.length());
            ch = baseNumLetter.charAt(dot) + "";
            sBuffer.append(ch);
            //正向旋转
            graphics.rotate(degree * Math.PI / 180, x, 45);
            graphics.drawString(ch, x, 45);
            //反向旋转
            graphics.rotate(-degree * Math.PI / 180, x, 45);
            x += 48;
        }
        //画干扰线
        for (int i = 0; i <6; i++) {
            // 设置随机颜色
                 graphics.setColor(getRandomColor());
            // 随机画线
                 graphics.drawLine(random.nextInt(width), random.nextInt(height),
                                    random.nextInt(width), random.nextInt(height));
        }
        //添加噪点
        for(int i=0;i<30;i++){
                 int x1 = random.nextInt(width);
                 int y1 = random.nextInt(height);
                 graphics.setColor(getRandomColor());
                 graphics.fillRect(x1, y1, 2,2);
                 }
        return sBuffer.toString();
    }
    /**
     * 随机取色
 
     */
    private static Color getRandomColor() {
        Random ran = new Random();
        Color color = new Color(ran.nextInt(256),
                ran.nextInt(256), ran.nextInt(256));
        return color;
    }
}