JavaWeb实现验证码

╰半橙微兮° 2022-07-10 12:32 219阅读 0赞

## JavaWeb实现验证码 ##

创建一个ImageServlet类，这个类实现了输出验证码的功能。具体代码如下：

ImageServlet:

@WebServlet("/ImageServlet")
    public class ImageServlet extends HttpServlet { 
        private static final long serialVersionUID = 1L;
    
        public ImageServlet() {
            super();
    
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
            response.setContentType("image/jpg;charset=utf-8");
    
            //在内存中创建一个图片对象，宽度120，高度30
            int width = 120;
            int height = 30;
            BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
            //获取一个绘制的对象
            Graphics g = image.getGraphics();
            //设置颜色为蓝色
            g.setColor(Color.BLUE);
            //画一个蓝色矩形
            g.drawRect(0, 0, width, height);
            //设置颜色灰色
            g.setColor(Color.GRAY); 
            //给图片进行填充灰色
            g.fillRect(2, 2, width-4, height-4);
            //设置颜色为红色
            g.setColor(Color.RED);
            //设置字体为黑体，大小20，字体样式加粗、斜体
            g.setFont(new Font("黑体", Font.BOLD|Font.ITALIC, 20));
    
            Random random = new Random();
            int position = 10;
            //随机绘制4个数字
            for (int i = 0; i < 4; i++) {
                String content= Integer.toString(random.nextInt(10));
                //绘制数字
                g.drawString(content,position, 20);
                //排列数字的位置
                position+=30;
            }
            //绘制8条干扰线
            for (int i = 0; i < 8; i++) {
                g.setColor(Color.DARK_GRAY);
                //绘制深灰色的干扰线
                g.drawLine(random.nextInt(width), random.nextInt(height), random.nextInt(width), random.nextInt(height));
            }
            //输出图片
            ImageIO.write(image ,"jpg", response.getOutputStream());
        }
    
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
            doGet(request, response);
        }
    
    }

在web.xml设置ImageServlet配置

<servlet>
        <servlet-name>ImageServlet</servlet-name>
        <servlet-class>com.yundoku.ImageServlet</servlet-class>
    </servlet>
    
    <servlet-mapping>
        <servlet-name>ImageServlet</servlet-name>
        <url-pattern>/image</url-pattern>
    </servlet-mapping>

image.html代码

<!DOCTYPE html>
    <html>
    <head>
    <meta charset="UTF-8">
    <title>Insert title here</title>
    <script type="text/javascript"> function changeImage() { var img = document.getElementsByTagName("img")[0]; img.src="/TomcatDemo/image?time="+new Date().getTime();//这个目的是防止缓存不刷新验证码 } </script>
    </head>
    <body>
        <form>
            <table>
                <tr align="left" height="30">
                    <td>用户名：</td>
                    <td><input type="text" name="username"/></td>
                </tr >
                <tr align="left" height="30">
                    <td>密码：</td>
                    <td><input type="password" name="password"/></td>
                </tr>
                <tr align="left" height="30">
                    <td>验证码：</td>
                    <td><input type="text" name="username"/>  <img src="/TomcatDemo/image" onclick="changeImage()"/> <a href="javascript:changeImage()" >看不清，换一张</a></td>
                </tr>
                <tr height="24"><td colspan="2"><input type="submit" value="提交"/></td></tr>
            </table>
        </form>
    </body>
    </html>

效果如图所示：

![image][]

[image]: http://oe9ggtbcb.bkt.clouddn.com/7.png