如何正确地将数据放入会话中，然后在自定义标签中使用它们？

Question

我正在使用servlet和自定义标签。我正在创建一个验证码。我有一个cappu MAP，其中的关键在于其ID和所生成的值。我如何使用自定义标签在jsp中插入验证码，我试图以某种方式进行监听，但这是我做错的，因为验证码未显示在页面上。告诉我我在哪里弄错了？

我生成验证码的班级：

public class CaptchaGenerator {
    private static final Logger LOG = Logger.getLogger(CaptchaGenerator.class);
    private CaptchaService captchaService;

    public CaptchaGenerator(CaptchaService captchaService) {
        this.captchaService = captchaService;
    }

    public void generateCaptcha(HttpServletResponse response) throws IOException {
        int width = 535;
        int height = 90;
        long id = System.currentTimeMillis(); //here is my captcha id generated

        BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        Graphics2D graphics2D = bufferedImage.createGraphics();

        Font font = new Font("Impact", Font.ITALIC, 34);
        graphics2D.setFont(font);
        graphics2D.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        Random random = new Random();

        int x = 0;
        int y;

        String captchaId = captchaService.setId(String.valueOf(id));

        captchaService.put(captchaId, String.valueOf(new Random().nextInt(99999) + 10000)); // here is i put generated param into my captcha map

        char[] code = captchaService.getElement(String.valueOf(captchaService.getId())).toCharArray();

        for (int i = 0; i < code.length; i++) {
            x += 75 + (Math.abs(random.nextInt()) % 20);
            y = 50 + (Math.abs(random.nextInt()) % 20);

            graphics2D.drawChars(captchaService.getElement(String.valueOf(captchaService.getId())).toCharArray(), i, 1, x, y);
        }

        LOG.debug("Your captcha map " + captchaService);
        LOG.debug("Generated id " + id);

        graphics2D.dispose();
        response.setContentType("image/png");
        OutputStream os = response.getOutputStream();
        ImageIO.write(bufferedImage, "png", os);
        os.close();
    }

我有一个问题，如何通过生成的id标记显示我的验证码，如何在jsp中正确执行以及哪里出了错？

自定义标签：

public class CaptchaCustomTag extends SimpleTagSupport {
    private static final Logger LOG = Logger.getLogger(CaptchaCustomTag.class);

    private String captchaId;

    public void setCaptchaId(String captchaId) {
    this.captchaId = captchaId;
}

    private String getCaptchaPNG() {

        return "<img src=\"captcha?id=" + captchaId + "\">";
    }

    private String getHidden() {
        return "<input type=\"hidden\" name=\"captchaID\" value=\"" + captchaId + "\">\n";
    }

    @Override
    public void doTag() throws JspException, IOException {
        getJspContext().getOut().write(getCaptchaPNG() + getHidden());
        LOG.debug("Captcha id: " + captchaId);
    }
}

如果我在此处创建我的验证码服务的副本，那么我生成的验证码将消失。

验证码服务：

public class CaptchaService implements service.CaptchaService {
    private Captcha captcha;
    private Map<String, String> captchaMap = new HashMap<>();

    public CaptchaService(Captcha captcha) {
        this.captcha = captcha;
    }

    @Override
    public boolean isExistValidCaptcha() {
        return !captchaMap.isEmpty();
    }

    @Override
    public String getCaptchaById(String id) {
        return captchaMap.get(id);
    }

    @Override
    public String setId(String id) {
        return captcha.setId(id);
    }

    @Override
    public String getId() {
        return captcha.getId();
    }

    @Override
    public String getElement(String key) {
        return captchaMap.get(key);
    }

    @Override
    public void put(String key, String value) {
        captchaMap.put(key, value);
    }

    @Override
    public void removeOldCaptcha(long captchaTime) {
        if (captchaMap.isEmpty()) {
            for (Map.Entry<String, String> entryMap : captchaMap.entrySet()) {
                long actualCaptchaTime = System.currentTimeMillis() - Long.valueOf(entryMap.getKey());
                if (actualCaptchaTime >= captchaTime) {
                    captchaMap.remove(entryMap.getKey());
                }
            }
        }
    }

我以这种方式插入我的标签，但是验证码不显示，我的二传手也显示从未使用过它吗？

<MyTags:captcha captchaId = "${captchaId}" />

TLD：

<?xml version="1.0" encoding="UTF-8" ?>
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
        version="2.0">
    <tlib-version>2.1</tlib-version>
    <short-name>MyTags</short-name>
    <uri>http://journaldev.com/jsp/tlds/MyTags</uri>
    <tag>
        <name>captcha</name>
        <tag-class>customtag.CaptchaCustomTag</tag-class>
        <body-content>empty</body-content>
        <attribute>
            <name>captchaId</name>
            <required>true</required>
            <rtexprvalue>true</rtexprvalue>
        </attribute>
    </tag>
</taglib>

Captcha Servlet：  私人CaptchaService captchaService;

@Override
public void init() throws ServletException {
    captchaService = (CaptchaService) getServletContext().getAttribute("captchaService");

}

   @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {

        CaptchaGenerator captchaGenerator = new CaptchaGenerator(captchaService);
        CaptchaTypeManager captchaTypeManager = new CaptchaTypeManager(req, resp, captchaService);

        captchaTypeManager.getType(getServletContext().getInitParameter(ConstantApp.ContextType.CONTEXT_TYPE));
        captchaGenerator.generateCaptcha(resp);

        LOG.debug(getServletContext().getInitParameter(ConstantApp.ContextType.CONTEXT_TYPE));
    }

注册表格：

<form action="registration" method="post" id="registration_form">

                        <h2><div align="center" style="color: #ff0000">${requestScope.error_time}</div></h2>
                    <ul>
                        <div id="error_first_name" style="color: #ff0000">${requestScope.error_first_name}</div>
                        <li class="text-info">First Name:</li>
                        <li><input type="text" id="fName" name="fName" placeholder="Your first name" value="${sessionScope.fName}"></li>
                    </ul>
                    <ul>
                        <div id="error_last_name" style="color: #ff0000">${requestScope.error_last_name}</div>
                        <li class="text-info">Last Name:</li>
                        <li><input type="text" id="lName" name="lName" placeholder="Your last name" value="${sessionScope.lName}"></li>
                    </ul>
                    <ul>
                        <div id="error_login" style="color: #ff0000">${requestScope.error_login}</div>
                        <li class="text-info">Login:</li>
                        <li><input type="text" id="login" name="login" placeholder="Your login" value="${sessionScope.login}"></li>
                    </ul>
                    <ul>
                        <div id="error_email" style="color: #ff0000">${requestScope.error_email}</div>
                        <li class="text-info">Email:</li>
                        <li><input type="text" id="email" name="email" placeholder="Your email" value="${sessionScope.email}"></li>
                    </ul>
                    <ul>
                        <div id="error_password" style="color: #ff0000">${requestScope.error_password}</div>
                        <li class="text-info">Password:</li>
                        <li><input type="password" id="pass" name="pass" placeholder="Your password"></li>
                    </ul>
                    <ul>
                        <div id="error_confirmPassword" style="color: #ff0000">${requestScope.error_confirmPassword}</div>
                        <li class="text-info">Re-enter Password:</li>
                        <li><input type="password" id="confPass" name="confPass" placeholder="Confirm your password"></li>
                    </ul>

                     <MyTags:captcha captchaId = "${captchaId}"/>
                     <br></br>
                     <div style="color: #ff0000" id="error_captcha">${requestScope.error_captcha}</div>
                     <input type="text" placeholder="Enter the code from the image" name="captchaCode" id="captchaCode"/>


                    <input type="submit" id="submit" value="Register Now">
                    <p class="click">By clicking this button, you agree to my modern style <a href="terms.jsp">Policy Terms and
                        Conditions</a> to Use</p>
                </form>

上下文监听器：

public class ContextListener implements ServletContextListener {
    private static final Logger LOG = Logger.getLogger(ContextListener.class);

    @Override
    public void contextInitialized(ServletContextEvent event) {
        dao.UserDAO dao = new UserDAO();
        service.UserService userService = new UserService(dao);
        Captcha captcha = new Captcha();
        CaptchaService captchaService = new service.impl.CaptchaService(captcha);

        event.getServletContext().setAttribute("captchaService", captchaService);
        event.getServletContext().setAttribute("userService", userService);

        ServletContext servletContext = event.getServletContext();
        initLog4J(servletContext);
    }

最后，当我按F12进行验证时，会得到一个空白字段。

<MyTags:captcha captchaId = ""/>

web.xml：

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
         id="WebApp_ID" version="2.5">
    <display-name>Shopper</display-name>
    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>

    <listener>
        <listener-class>listener.ContextListener</listener-class>
    </listener>

    <context-param>
        <param-name>type</param-name>
        <param-value>cookies</param-value>
    </context-param>
    <context-param>
        <param-name>registrationTime</param-name>
        <param-value>60</param-value>
    </context-param>
    <jsp-config>
        <taglib>
            <taglib-uri>http://journaldev.com/jsp/tlds/MyTags</taglib-uri>
            <taglib-location>/WEB-INF/captchaTag.tld</taglib-location>
        </taglib>
    </jsp-config>
</web-app>

RegistarionServlet：

@WebServlet("/registration")
public class RegistrationServlet extends HttpServlet {
    private static final Logger LOG = Logger.getLogger(RegistrationServlet.class);

    private long startTime;

    private UserService userService;
    private CaptchaService captchaService;

    @Override
    public void init() throws ServletException {
        userService = (UserService) getServletContext().getAttribute("userService");
        captchaService = (CaptchaService) getServletContext().getAttribute("captchaService");
    }

    @Override
    protected void doGet(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws ServletException, IOException {
        startTime = System.currentTimeMillis();
        httpServletRequest.getRequestDispatcher(ConstantApp.JSPPages.REGISTRATION_PAGE).forward(httpServletRequest, httpServletResponse);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        RegistrationInfo registrationInfo = new RegistrationInfoImpl(request);
        Map<String, String> validationError = Validation.validate(registrationInfo);
        String contextType = getServletContext().getInitParameter(ConstantApp.ContextType.CONTEXT_TYPE);
        ChooseStrategy chooseStrategy = new ChooseStrategy(contextType, request, captchaService);
        boolean isValidateCaptcha = chooseStrategy.chooseStrategy(contextType);
        boolean isValidTime = RegistrationTimer.isValidRegistrationTime(startTime, Integer.parseInt(getServletContext().getInitParameter(ConstantApp.ContextType.CONTEXT_REGISTRATION_TIME)));

        LOG.debug("Validation error map: " + validationError.entrySet());
        if (validationError.isEmpty() && !userService.isExist(registrationInfo.getLogin()) && isValidateCaptcha && isValidTime) {
            userService.add(new User(registrationInfo.getLogin(), registrationInfo.getFirstName(), registrationInfo.getLastName(), registrationInfo.getEmail(), registrationInfo.getPassword()));
            LOG.debug("All users: " + userService.getAll());
            request.getRequestDispatcher(ConstantApp.JSPPages.INDEX_PAGE).forward(request, response);
        }

我发布了主要课程，如果需要更多内容，我将添加）。如何将我的ID码传递给标签以显示它？我想进行生成，将其放入会话中，然后调用验证码servlet并将其添加到标签中。但是我该怎么办呢，我真的想不起来？