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java - 连接到 .java 类的 .JSP 和 servlet

转载 作者：行者123 更新时间：2023-12-02 05:45:22 30 4
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我在尝试运行我的程序时遇到问题。它应该从 JSP 页面获取信息到 servlet，以便可以通过 java 类中的方法传递信息进行验证。然后，一旦验证成功，servlet 就会确定是将消息发送到前一个 JSP 页面还是发送到成功的 JSP 页面。当我运行该程序时，它会将我带到 RegisterUser.jsp 页面。我输入信息，然后点击提交。它让我进入 404 未找到页面。该链接说它试图将我指向 CreateUser.java servlet。它不应该这样做。任何帮助将不胜感激，无论它只是我可以找到信息的链接还是一些实际的解决方案帮助。谢谢。

  1. CreateUser.java SERVLET:

    @WebServlet(name = "createUser", urlPatterns = {"/createUser"})
     public class CreateUser extends HttpServlet {

    /**
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
     * methods.
     *
     * @param req
     * @param resp
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */

         protected void processRequest(HttpServletRequest req, HttpServletResponse resp)   throws ServletException, IOException {
        System.out.println("in process login.java");
        ServletContext context = getServletContext();

        // Extract password and id from login.jsp form

        String userName = req.getParameter("USERNAME");
        String password = req.getParameter("PASSWORD");
        String answerOne = req.getParameter("ANSWERONE");
        String answerTwo = req.getParameter("ANSWERTWO");
        String answerThree = req.getParameter("ANSWERTHREE");

        Boolean duplicateUser = User.verifyUserExists(userName);

        HttpSession session = req.getSession();
        if (duplicateUser) {
            req.setAttribute("MESSAGE", "UserName is in use. Try again");
            context.getRequestDispatcher("/RegisterUser.jsp").forward(req, resp);
        }
        else{
            User user = new User(userName, password, answerOne, answerTwo, answerThree);
            user.addUser(user);
            req.getRequestDispatcher("RegistrationSuccessful.jsp").forward(req, resp);
        }

    }

    }

  2. RegisterUser.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
         pageEncoding="ISO-8859-1"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">
<HTML>

    <body>
        <H1>New User Registration</H1>
        <H3>Required Information</H3>

        <FORM name="CREATE" action="servlets/CreateUser.java" method="POST" >
            <table>
                <tr>
                    <td>Username:</td>
                    <td><INPUT name="USERNAME" maxlength="50" size="40" type="text" ></TD>
                </tr>
                <tr>
                    <td>Password:</td>
                    <td><INPUT name="PASSWORD" maxlength="50" size="40" type="password" ></td>
                </tr>
                <tr>
                    <td>Favorite Vacation Spot:</td>
                    <td><INPUT name="ANSWERONE" maxlength="50" size="40" type="text" ></TD>
                </tr>
                <tr>
                    <td>Mother's Maiden Name:</td>
                    <td><INPUT name="ANSWERTWO" maxlength="50" size="40" type="text" ></TD>
                </tr>
                <tr>
                    <td>First Pet's Name:</td>
                    <td><INPUT name="ANSWERTHREE" maxlength="50" size="40" type="text" ></TD>
                </tr>
                <tr>
                    <td><input type="submit" name="Register" value="Register" onClick = "CreateUser.java"></td>
                    <td></td>
                </tr>
            </table>
        </FORM>
        <p>${MESSAGE}</p>

    </BODY>
</HTML>
  1. User.java 类

公共(public)类用户{

private String userName;
private String password;
    private String answerOne;
    private String answerTwo;
    private String answerThree;
    private static File file = new File("C:\\Users.txt");

    @SuppressWarnings("OverridableMethodCallInConstructor")
    public User(String un, String pw, String a1, String a2, String a3) {
        setUserName(un);
        setPassword(pw);
        setAnswerOne(a1);
        setAnswerTwo(a2);
        setAnswerThree(a3);

    }

    public void addUser(User user) throws IOException {
        FileWriter fw = new FileWriter(getFile());
        try (BufferedWriter bfw = new BufferedWriter(fw)) {
            bfw.write(user.userName);
            bfw.write(user.password);
            bfw.write(user.answerOne);
            bfw.write(user.answerTwo);
            bfw.write(user.answerThree);
            bfw.newLine();
        }

    }

    public static boolean verifyUserExists(String userName) throws FileNotFoundException {
        Scanner scannedFile = new Scanner(getFile());
        while (scannedFile.hasNext()) {
            String search = scannedFile.next();
            return search.equals(userName);
        }
        return false;
    }

    public static Boolean verifyPassword(String userName, String password) throws FileNotFoundException {
        Scanner scannedFile = new Scanner(getFile());
        while (scannedFile.hasNext()) {
            String search = scannedFile.next();
            if (search.equals(userName)) {
                return scannedFile.nextLine().equals(getMD5(password));
            }
        }
        return false;
    }

    public static String getMD5(String input) {
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            byte[] messageDigest = md.digest(input.getBytes());
            BigInteger number = new BigInteger(1, messageDigest);
            String hashtext = number.toString(16);
            // Now we need to zero pad it if you actually want the full 32 chars.
            while (hashtext.length() < 32) {
                hashtext = "0" + hashtext;
            }
            return hashtext;
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        }
    }

    public static File getFile() {
        return file;
    }

最佳答案

使用

 action="createUser" OR action="./createUser"
<小时/>

action="/createUser"将调用默认上下文的 URL 

http://localhost:8084/createUser

while action="./createUser"将调用当前目录/上下文中 servlet 的 URL 模式

 http://localhost:8084/ContextName/createUser

关于java - 连接到 .java 类的 .JSP 和 servlet，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/24127066/

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