Using Java to build the password retrieval function of the online examination system

Java is a powerful programming language that is widely used in various fields. In the development of online examination systems, the password retrieval function is very important for users, which can help users quickly recover their login passwords. This article will introduce how to use Java to build the password retrieval function of the online examination system and give specific code examples.

1. Requirements analysis for password retrieval function

The password retrieval function of the online examination system needs to meet the following basic requirements:

1. Users can provide it when registering Email or mobile phone number to retrieve password.
2. The system needs to verify the user's identity and ensure that the email or mobile phone number entered is consistent with the one bound during registration.
3. The system provides a password reset function after successful verification, and users can set a new login password.
4. After the password is reset successfully, the user can receive a prompt message indicating that the password has been reset successfully.

2. Implementation process of the password retrieval function

The following will take a Java-based online examination system as an example to demonstrate the specific implementation process of the password retrieval function.

1. Database design

First, you need to design a database to store the user's registration information and verification information for retrieving the password. You can create a user table (user) and a password recovery table (password_recovery). The relationship between the two is a one-to-one relationship. The user table stores the user's basic information, and the password retrieval table stores information related to the user's password retrieval, including verification links, expiration time, etc.

The user table (user) fields are designed as follows:

• id (INT): User ID
• username (VARCHAR): User name
• email (VARCHAR): Email
• phone (VARCHAR): Mobile phone number
• password (VARCHAR): Login password

Password recovery table (password_recovery) field design As follows:

• id (INT): Retrieve password ID
• user_id (INT): User ID
• token (VARCHAR): Verification link (generates a string Random string)
• expire_time (DATETIME): Expiration time

2. Send verification link

When the user needs to retrieve the password, the system first needs to send verification Link to the email or mobile phone number provided by the user when registering. In Java, you can use the JavaMail API to send emails, or the Java SMS interface to send text messages.

The following takes sending emails as an example and gives specific code examples:

import javax.mail.*;
import javax.mail.internet.*;
import java.util.Properties;

public class EmailUtil {
    public static void sendEmail(String toEmail, String subject, String content) throws MessagingException {
        final String username = "your_email@gmail.com"; // 你的邮箱地址
        final String password = "your_email_password"; // 你的邮箱密码

        Properties props = new Properties();
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.starttls.enable", "true");
        props.put("mail.smtp.host", "smtp.gmail.com");
        props.put("mail.smtp.port", "587");

        Session session = Session.getInstance(props, new Authenticator() {
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(username, password);
            }
        });

        Message message = new MimeMessage(session);
        message.setFrom(new InternetAddress(username));
        message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(toEmail));
        message.setSubject(subject);
        message.setText(content);

        Transport.send(message);
        System.out.println("邮件已发送！");
    }
}

The above code is a tool class for sending emails, and you need to set your own email address and password. Call the sendEmail method of EmailUtil and pass in the recipient address, email subject and email content to send the email.

3. Verification link generation and expiration time settings

When the user clicks the verification link, the system needs to verify whether the link is valid and expired. To generate a verification link, you can use Java's UUID class to generate a unique random string, save the string to the password retrieval table, and set the expiration time to the current time plus a preset validity period, such as one day.

The following is a code example:

import java.util.UUID;

public class TokenUtil {
    public static String generateToken() {
        return UUID.randomUUID().toString().replace("-", "");
    }
}

The above code is a Token generation tool class. Call the generateToken method of TokenUtil to generate a 32-bit unique string.

The expiration time can be set using Java's Date class and Calendar class:

import java.util.Date;
import java.util.Calendar;

public class ExpireTimeUtil {
    public static Date getExpireTime() {
        Calendar calendar = Calendar.getInstance();
        calendar.add(Calendar.DAY_OF_MONTH, 1); // 指定过期时间为当前时间加上一天
        return calendar.getTime();
    }
}

The above code is an expiration time setting tool class. Call the getExpireTime method of ExpireTimeUtil to get a set preset validity period. expiration time.

4. Verification link verification and password reset

When the user clicks the verification link, the system needs to verify the validity and expiration of the link. If verification passes, the user is allowed to reset their password.

The following is a code example:

import java.util.Date;

public class PasswordRecovery {
    public static boolean validateToken(String token) {
        // 通过token查询密码找回表，判断验证链接是否有效
        
        return false;
    }
    
    public static boolean isExpired(Date expireTime) {
        // 判断验证链接是否过期
        
        return false;
    }
    
    public static void resetPassword(String token, String newPassword) {
        // 通过token更新用户表中的密码
    }
}

The above code is a password retrieval class, in which the validateToken method is used to verify the validity of the verification link, the isExpired method is used to determine whether the verification link has expired, and resetPassword Method is used to reset the user's password.

3. Summary

This article introduces how to use Java to build the password retrieval function of the online examination system, and gives specific code examples. According to specific business needs, the code implementation method can be appropriately adjusted and expanded. The implementation process of the password retrieval function is relatively cumbersome, but through reasonable design and code implementation, it can provide a good user experience, help users quickly retrieve passwords, and ensure the security of the system.

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