Initial commit

src/Base/Email_settings.java

@@ -0,0 +1,13 @@
+package Base;
+
+public class Email_settings {
+    public static final String SMTP_HOST = "smtp.qq.com";
+    // 邮箱服务器端口
+    public static final String SMTP_PORT = "587";
+    // 发件人邮箱
+    public static final String FROM_EMAIL = "835981889@qq.com";
+    // 发件人邮箱授权码
+    public static final String EMAIL_PASSWORD = "fpqfprqznbvdbcdf";
+    // 是否启用SSL
+    public static final boolean SSL_ENABLE = true;
+}

src/Base/Question.java

@@ -0,0 +1,267 @@
+package Base;
+
+import java.util.HashMap;
+import java.util.Random;
+import java.util.Stack;
+
+public class Question {
+    private int number;
+    private String content;
+    private String type;
+    private String answer;
+    private String[] options;
+    private final Random ra= new Random();
+    public static final HashMap<String, String> trigValues = new HashMap<>();
+
+    static {
+        // 15°
+        trigValues.put("sin(15°)", "√2*(√3-1)/4");
+        trigValues.put("cos(15°)", "√2*(√3+1)/4");
+        trigValues.put("tan(15°)", "(2-√3)");
+        trigValues.put("sin²(15°)", "(2-√3)/4");
+        trigValues.put("cos²(15°)", "(2+√3)/4");
+        trigValues.put("tan²(15°)", "(7-4*√3)");
+
+        // 22.5°
+        trigValues.put("sin(22.5°)", "√0.59/2"); //√(2-√2)/2
+        trigValues.put("cos(22.5°)", "√3.41/2"); //√(2+√2)/2
+        trigValues.put("tan(22.5°)", "(√2-1)");
+        trigValues.put("sin²(22.5°)", "(2-√2)/4");
+        trigValues.put("cos²(22.5°)", "(2+√2)/4");
+        trigValues.put("tan²(22.5°)", "(3-2*√2)");
+
+        // 75°
+        trigValues.put("sin(75°)", "√2*(√3+1)/4");
+        trigValues.put("cos(75°)", "√2*(√3-1)/4");
+        trigValues.put("tan(75°)", "(2+√3)");
+        trigValues.put("sin²(75°)", "(2+√3)/4");
+        trigValues.put("cos²(75°)", "(2-√3)/4");
+        trigValues.put("tan²(75°)", "(7+4*√3)");
+
+        // 105°
+        trigValues.put("sin(105°)", "√2*(√3+1)/4");
+        trigValues.put("cos(105°)", "√2*(1-√3)/4");
+        trigValues.put("tan(105°)", "(0-(2+√3))");
+        trigValues.put("sin²(105°)", "(2+√3)/4");
+        trigValues.put("cos²(105°)", "(2-√3)/4");
+        trigValues.put("tan²(105°)", "(7+4*√3)");
+
+        // 120°
+        trigValues.put("sin(120°)", "√3/2");
+        trigValues.put("cos(120°)", "(0-1/2)");
+        trigValues.put("tan(120°)", "(0-√3)");
+        trigValues.put("sin²(120°)", "3/4");
+        trigValues.put("cos²(120°)", "1/4");
+        trigValues.put("tan²(120°)", "3");
+
+        // 135°
+        trigValues.put("sin(135°)", "√2/2");
+        trigValues.put("cos(135°)", "(0-√2/2)");
+        trigValues.put("tan(135°)", "(0-1)");
+        trigValues.put("sin²(135°)", "1/2");
+        trigValues.put("cos²(135°)", "1/2");
+        trigValues.put("tan²(135°)", "1");
+
+        // 150°
+        trigValues.put("sin(150°)", "1/2");
+        trigValues.put("cos(150°)", "(0-√3/2)");
+        trigValues.put("tan(150°)", "(0-√3/3)");
+        trigValues.put("sin²(150°)", "1/4");
+        trigValues.put("cos²(150°)", "3/4");
+        trigValues.put("tan²(150°)", "1/3");
+
+        // 210°
+        trigValues.put("sin(210°)", "(0-1/2)");
+        trigValues.put("cos(210°)", "(0-√3/2)");
+        trigValues.put("tan(210°)", "√3/3");
+        trigValues.put("sin²(210°)", "1/4");
+        trigValues.put("cos²(210°)", "3/4");
+        trigValues.put("tan²(210°)", "1/3");
+
+        // 300°
+        trigValues.put("sin(300°)", "(0-√3/2)");
+        trigValues.put("cos(300°)", "1/2");
+        trigValues.put("tan(300°)", "(0-√3)");
+        trigValues.put("sin²(300°)", "3/4");
+        trigValues.put("cos²(300°)", "1/4");
+        trigValues.put("tan²(300°)", "3");
+    }
+
+    public Question(int number, String content, String type) {
+        this.number = number;
+        this.content = content;
+        this.type = type;
+        options=new String[4];
+    }
+
+    public int getNumber() { return number; }
+    public String getContent() { return content; }
+    public String getType() { return type; }
+    public String getAnswer() {return answer;}
+    public String getOptions(int i) {return options[i];}
+
+    @Override
+    public String toString(){
+        return this.number+". "+this.content+" = ?";
+    }
+
+    public void set_options(){
+        answer=calculate(this.content);
+        int which=ra.nextInt(4);
+        options[which]=answer;
+        for (int i=0;i<4;i++) {
+            if (i != which) {
+                if (this.type.equals("高中")) {
+                    options[i] = answer.equals("不可解") ? String.format("%.2f", Math.sqrt(3) * ra.nextInt(10) + ra.nextDouble(1)) :
+                            String.format("%.2f", Double.parseDouble(answer) + Math.sqrt(2) * ra.nextInt(5));
+                } else {
+                    if (Double.parseDouble(answer) ==Math.floor(Double.parseDouble(answer)) ) {
+                        options[i] = answer.equals("不可解") ? String.valueOf((int) ra.nextInt(1000) + ra.nextInt(10)) :
+                                String.valueOf((int) Double.parseDouble(answer) + ra.nextInt(10));
+                    } else {
+                        options[i] = answer.equals("不可解") ? String.format("%.2f", ra.nextInt(1000) + ra.nextDouble(10)) :
+                                String.format("%.2f", Double.parseDouble(answer) + ra.nextDouble(10));
+                    }
+                }
+                for (int j = 0; j < i; j++) {
+                    if (options[j].equals(options[i])) {
+                        i--;
+                        break;
+                    }
+                }
+                if (options[i].equals(answer)) {
+                    i--;
+                }
+            }
+        }
+    }
+
+    public String calculate(String question){
+        try {
+            String expr = question.replaceAll(" ", "");
+            double result;
+            if (!type.equals("高中")) {
+                result = deal_calculate(expr);
+                if (Double.isNaN(result) || Double.isInfinite(result)) {
+                    return "不可解";
+                }
+                if (result == Math.floor(result)) {
+                    return String.valueOf((int) result);
+                } else {
+                    return String.format("%.2f", result);
+                }
+            }
+            else{
+                return deal_sen_calculate(expr);
+            }
+        } catch (Exception e) {
+            return "不可解";
+        }
+    }
+
+    private double deal_calculate(String expr){
+        Stack<Double> numbers = new Stack<>();
+        Stack<Character> operators = new Stack<>();
+        expr=expr.replace("²", "^2");
+        for (int i = 0; i < expr.length(); i++) {
+            char c = expr.charAt(i);
+            if (Character.isDigit(c)) {
+                StringBuilder temp = new StringBuilder();
+                while (i < expr.length() && (Character.isDigit(expr.charAt(i)) || expr.charAt(i) == '.')) {
+                    temp.append(expr.charAt(i++));
+                }
+                i--;
+                numbers.push(Double.parseDouble(temp.toString()));
+            } else if (c == '(') {
+                operators.push(c);
+            } else if (c == ')') {
+                while (operators.peek() != '(') {
+                    numbers.push(Deal_Operator(operators.pop(), numbers.pop(), numbers.pop()));
+                }
+                operators.pop();
+            } else if (isOperator(c)) {
+                while (!operators.isEmpty() && hasPrecedence(c, operators.peek())) {
+                    numbers.push(Deal_Operator(operators.pop(), numbers.pop(), numbers.pop()));
+                }
+                operators.push(c);
+            }
+            else if (c == '√'){
+                i++;
+                StringBuilder temp = new StringBuilder();
+                while (i < expr.length() && (Character.isDigit(expr.charAt(i)) || expr.charAt(i) == '.')) {
+                    temp.append(expr.charAt(i++));
+                }
+                i--;
+                numbers.push(Math.sqrt(Double.parseDouble(temp.toString())));
+            }
+        }
+        while (!operators.isEmpty()) {
+            numbers.push(Deal_Operator(operators.pop(), numbers.pop(), numbers.pop()));
+        }
+        return numbers.pop();
+    }
+
+    private String deal_sen_calculate(String m_expr){
+        try {
+            String expr = m_expr.replaceAll(" ", "");
+            StringBuilder result = new StringBuilder();
+
+            int i = 0;
+            while (i < expr.length()) {
+                char c = expr.charAt(i);
+                if (c == 's' || c == 'c' || c == 't') {
+                    StringBuilder trigFunc = new StringBuilder();
+                    while (i < expr.length() && expr.charAt(i) != ')') {
+                        trigFunc.append(expr.charAt(i++));
+                    }
+                    trigFunc.append(')'); // 添加右括号
+                    String trigKey = trigFunc.toString();
+                    String trigValue = trigValues.get(trigKey);
+                    if (trigValue != null) {
+                        result.append(trigValue);
+                    }
+                } else if (isOperator(c) || c == '(' || c == ')') {
+                    result.append(c);
+                }
+                i++;
+            }
+            return String.format("%.2f",deal_calculate(Deal_Expression(result.toString())));
+        } catch (Exception e) {
+            return "不可解";
+        }
+    }
+
+    private double Deal_Operator(char operator, double b, double a) {
+        switch (operator) {
+            case '+': return a + b;
+            case '-': return a - b;
+            case '*': return a * b;
+            case '/': {
+                if (b == 0) throw new ArithmeticException("除零错误");
+                return a / b;
+            }
+            case '^': return Math.pow(a, b);
+            default: return 0;
+        }
+    }
+
+    private boolean isOperator(char c) {
+        return c == '+' || c == '-' || c == '*' || c == '/' || c == '^';
+    }
+
+    //检验运算优先级，来决定先计算再压栈还是直接压栈
+    private boolean hasPrecedence(char op1, char op2) {
+        if ( (op2 == '(' || op2 == ')')
+        || ((op1 == '*' || op1 == '/') && (op2 == '+' || op2 == '-'))
+        || (op1 == '^' && (op2 == '*' || op2 == '/' || op2 == '+' || op2 == '-'))) {
+            return false;
+        }
+        return true;
+    }
+
+    private String Deal_Expression(String expr) {
+        String simplified = expr.replace("+-","-");
+        simplified = simplified.replace("--","+");
+        return simplified;
+    }
+}

src/Base/User.java

@@ -0,0 +1,32 @@
+package Base;
+
+public class User {
+    private String email;
+    private String password;
+
+
+    public User(String email) {
+        this.email = email;
+    }
+
+    public String get_email() { return email; }
+    public String get_password() { return password; }
+    public void set_password(String password) { this.password = password; }
+
+    public static boolean check_password(String password) {
+        if (password == null || password.length() < 6 || password.length() > 20) {
+            return false;
+        }
+
+        boolean hasUpper = false;
+        boolean hasLower = false;
+        boolean hasDigit = false;
+
+        for (char c : password.toCharArray()) {
+            if (Character.isUpperCase(c)) hasUpper = true;
+            if (Character.isLowerCase(c)) hasLower = true;
+            if (Character.isDigit(c)) hasDigit = true;
+        }
+        return hasUpper && hasLower && hasDigit;
+    }
+}

src/Generator/G_ques.java

@@ -0,0 +1,8 @@
+package Generator;
+
+public interface G_ques {
+    String g_question();
+    String g_type();
+    char g_operator();
+    String add_brackets(StringBuilder s,int count);
+}

src/Generator/Jun_g_ques.java

@@ -0,0 +1,82 @@
+package Generator;
+
+import java.util.Random;
+
+public class Jun_g_ques implements G_ques{
+    private Random ra= new Random();
+
+    @Override
+    public String g_question() {
+        int count=ra.nextInt(5)+1;
+        StringBuilder question = new StringBuilder();
+        boolean flag=false;
+        for (int i=0;i<count;i++){
+            if (i>0){
+                question.append(" ").append(g_operator()).append(" ");
+            }
+            if (ra.nextDouble()<0.25) {
+                if (ra.nextBoolean()) {
+                    question.append(ra.nextInt(30) + 1).append("²");
+                }
+                else {
+                    question.append("√").append(ra.nextInt(100) + 1);
+                }
+                flag=true;
+            }
+            else {
+                question.append(ra.nextInt(100) + 1);
+            }
+        }
+        if (!flag){
+            if(count==1){
+                if (ra.nextBoolean()){
+                    question.append("²");
+                }
+                else {
+                    question.insert(0,"√");
+                }
+            }
+            else {
+                String[] parts = question.toString().split(" ");
+                int pos = ra.nextInt(count);
+                if (ra.nextBoolean()) {
+                    parts[pos * 2] = parts[pos * 2] + "²";
+                } else {
+                    parts[pos * 2] = "√" + parts[pos * 2];
+                }
+                question = new StringBuilder(String.join(" ", parts));
+            }
+        }
+        return add_brackets(question,count);
+    }
+
+    @Override
+    public String g_type(){
+        return "初中";
+    }
+
+    @Override
+    public char g_operator(){
+        char[] op={'+','-','*','/'};
+        return op[ra.nextInt(op.length)];
+    }
+
+    @Override
+    public String add_brackets(StringBuilder s,int count){
+        String res=s.toString();
+        String[] parts=s.toString().split(" ");
+        if (ra.nextBoolean()&&parts.length!=1) {
+            int num=ra.nextInt(3)+1;
+            for (int i=0;i<num;i++) {
+                int pos = ra.nextInt(count);
+                if (pos==count-1){
+                    pos=pos-1;
+                }
+                parts[pos * 2] = "(" + parts[pos * 2];
+                parts[parts.length-1]=parts[parts.length-1]+")";
+            }
+            res = String.join(" ", parts);
+        }
+        return res;
+    }
+}

src/Generator/Pri_g_ques.java

@@ -0,0 +1,44 @@
+package Generator;
+
+import java.util.Random;
+
+public class Pri_g_ques implements G_ques{
+    private Random ra= new Random();
+
+    @Override
+    public String g_question() {
+        int count=ra.nextInt(4)+2;
+        StringBuilder question = new StringBuilder();
+        int count_bracket=0;
+        for (int i=0;i<count;i++) {
+            if (i > 0) {
+                question.append(" ").append(g_operator()).append(" ");
+            }
+            if (i!=count-1&&ra.nextDouble()<0.4){
+                question.append("(");
+                count_bracket++;
+            }
+            question.append(ra.nextInt(100) + 1);
+        }
+        if (count_bracket!=0){
+            question.append(")".repeat(Math.max(0, count_bracket)));
+        }
+        return question.toString();
+    }
+
+    @Override
+    public String g_type(){
+        return "小学";
+    }
+
+    @Override
+    public char g_operator(){
+        char[] op={'+','-','*','/'};
+        return op[ra.nextInt(op.length)];
+    }
+
+    @Override
+    public String add_brackets(StringBuilder s,int count){
+        return  s.toString();
+    }
+}

src/Generator/Sen_g_ques.java

@@ -0,0 +1,64 @@
+package Generator;
+
+import java.util.Random;
+
+public class Sen_g_ques implements G_ques{
+    private Random ra= new Random();
+
+    @Override
+    public String g_question() {
+        int count=ra.nextInt(5)+1;
+        StringBuilder question = new StringBuilder();
+        for (int i=0;i<count;i++) {
+            if (i > 0) {
+                question.append(" ").append(g_operator()).append(" ");
+            }
+            if (ra.nextDouble()<0.3){
+                question.append(g_trig()).append("²").append("(").append(g_angle()).append("°)");
+            }
+            else {
+                question.append(g_trig()).append("(").append(g_angle()).append("°)");
+            }
+        }
+        return add_brackets(question,count);
+    }
+
+    @Override
+    public String g_type(){
+        return "高中";
+    }
+
+    @Override
+    public char g_operator(){
+        char[] op={'+','-','*','/'};
+        return op[ra.nextInt(op.length)];
+    }
+
+    public String g_trig(){
+        String[] trig={"sin","cos","tan"};
+        return trig[ra.nextInt(trig.length)];
+    }
+
+    public String g_angle(){
+        String[] angle={"15","22.5","75","105","120","135","150","210","300"};
+        return angle[ra.nextInt(angle.length)];
+    }
+
+    public String add_brackets(StringBuilder s,int count){
+        String res=s.toString();
+        String[] parts=s.toString().split(" ");
+        if (ra.nextBoolean()&&parts.length!=1) {
+            int num=ra.nextInt(3)+1;
+            for (int i=0;i<num;i++) {
+                int pos = ra.nextInt(count);
+                if (pos==count-1){
+                    pos=pos-1;
+                }
+                parts[pos * 2] = "(" + parts[pos * 2];
+                parts[parts.length-1]=parts[parts.length-1]+")";
+            }
+            res = String.join(" ", parts);
+        }
+        return res;
+    }
+}

src/Send_Email/Deal_i_code.java

@@ -0,0 +1,53 @@
+package Send_Email;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class Deal_i_code{
+    private static final Map<String, I_Code> codeMap = new ConcurrentHashMap<>();
+
+    private static class I_Code {
+        String code;
+        long createTime;
+        private static final long EXPIRATION_TIME = 5 * 60 * 1000;
+
+        I_Code(String code) {
+            this.code = code;
+            this.createTime = System.currentTimeMillis();
+        }
+
+        boolean isExpired() {
+            return System.currentTimeMillis() - createTime > EXPIRATION_TIME;
+        }
+    }
+
+    public static String generate_code(String email) {
+        String code = Generate_i_code.generateCode(6);
+        codeMap.put(email, new I_Code(code));
+        return code;
+    }
+
+    public static boolean judge_code(String email, String inputCode) {
+        I_Code codeInfo = codeMap.get(email);
+        if (codeInfo == null) {
+            return false;
+        }
+        if (codeInfo.isExpired()) {
+            codeMap.remove(email);
+            return false;
+        }
+        boolean isValid = codeInfo.code.equals(inputCode);
+        if (isValid) {
+            codeMap.remove(email);
+        }
+        return isValid;
+    }
+
+    public static void clean_codes() {
+        codeMap.entrySet().removeIf(entry -> entry.getValue().isExpired());
+    }
+
+    public static void clean_all_codes(){
+        codeMap.clear();
+    }
+}

src/Send_Email/Generate_i_code.java

@@ -0,0 +1,18 @@
+package Send_Email;
+
+import java.util.Random;
+
+public class Generate_i_code {
+    public static String generateCode(int length) {
+        Random ra = new Random();
+        StringBuilder code = new StringBuilder();
+        for (int i = 0; i < length; i++) {
+            if (ra.nextBoolean()){
+                code.append((char)('A'+ra.nextInt(26)));
+            } else {
+                code.append((char)('0'+ra.nextInt(10)));
+            }
+        }
+        return code.toString();
+    }
+}

src/Send_Email/Send_email.java

@@ -0,0 +1,107 @@
+package Send_Email;
+
+import Base.Email_settings;
+
+import javax.mail.*;
+import javax.mail.internet.InternetAddress;
+import javax.mail.internet.MimeMessage;
+import java.util.Properties;
+import java.util.regex.Pattern;
+
+public class Send_email {
+    public static boolean judge_email_address(String email) {
+        if (email == null || email.trim().isEmpty()) {
+            System.out.println("邮箱不能为空");
+            return false;
+        }
+        // 去除前后空格
+        email = email.trim();
+        // 检查长度
+        if (email.length() > 254) { // RFC标准规定邮箱最大长度
+            System.out.println("邮箱地址过长");
+            return false;
+        }
+        // 检查是否包含@
+        if (!email.contains("@")) {
+            System.out.println("邮箱格式错误：缺少@符号");
+            return false;
+        }
+        // 分割本地部分和域名部分
+        String[] parts = email.split("@");
+        if (parts.length != 2) {
+            System.out.println("邮箱格式错误：只能有一个@符号");
+            return false;
+        }
+        String localPart = parts[0];
+        String domainPart = parts[1];
+        // 验证本地部分
+        if (localPart.isEmpty()) {
+            System.out.println("邮箱格式错误：@前必须有内容");
+            return false;
+        }
+        if (localPart.length() > 64) {
+            System.out.println("邮箱格式错误：@前内容过长");
+            return false;
+        }
+        // 验证域名部分
+        if (domainPart.isEmpty()) {
+            System.out.println("邮箱格式错误：@后必须有内容");
+            return false;
+        }
+        if (!domainPart.contains(".")) {
+            System.out.println("邮箱格式错误：域名不完整");
+            return false;
+        }
+        // 验证顶级域名
+        String[] domainParts = domainPart.split("\\.");
+        String topLevelDomain = domainParts[domainParts.length - 1];
+        if (topLevelDomain.length() < 2) {
+            System.out.println("邮箱格式错误：顶级域名太短");
+            return false;
+        }
+        String emailRegex = "^(?=.{1,64}@)[A-Za-z0-9_-]+(\\.[A-Za-z0-9_-]+)*@"
+                + "[^-][A-Za-z0-9-]+(\\.[A-Za-z0-9-]+)*(\\.[A-Za-z]{2,})$";
+        boolean matches = Pattern.matches(emailRegex, email);
+        System.out.println(matches ? "" : "邮箱格式错误");
+        return matches;
+    }
+
+    public static boolean send_email(String toEmail, String Code) {
+        try {
+            Properties props = new Properties();
+            props.put("mail.smtp.host", Email_settings.SMTP_HOST);
+            props.put("mail.smtp.port", Email_settings.SMTP_PORT);
+            props.put("mail.smtp.auth", "true");
+            if (Email_settings.SSL_ENABLE) {
+                props.put("mail.smtp.starttls.enable", "true");
+                props.put("mail.smtp.ssl.trust", Email_settings.SMTP_HOST);
+            }
+            // 创建会话
+            Session session = Session.getInstance(props, new Authenticator() {
+                @Override
+                protected PasswordAuthentication getPasswordAuthentication() {
+                    return new PasswordAuthentication(Email_settings.FROM_EMAIL, Email_settings.EMAIL_PASSWORD);
+                }
+            });
+            // 创建邮件消息
+            Message message = new MimeMessage(session);
+            message.setFrom(new InternetAddress(Email_settings.FROM_EMAIL));
+            message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(toEmail));
+            message.setSubject("注册验证码");
+            // 邮件内容
+            String content = String.format(
+                    "尊敬的用户：<b>%s</b><br/><br/>" +
+                            "您的注册验证码是：<b>%s</b><br/><br/>" +
+                            "验证码有效期为5分钟，请尽快完成注册。<br/><br/>" +
+                            "如果不是您本人操作，请忽略此邮件。",
+                    toEmail,Code
+            );
+            message.setContent(content, "text/html;charset=UTF-8");
+            // 发送邮件
+            Transport.send(message);
+            return true;
+        } catch (Exception e) {
+            return false;
+        }
+    }
+}

src/Service/Generate_paper.java

@@ -0,0 +1,39 @@
+package Service;
+
+import Base.Question;
+import Generator.G_ques;
+import Generator.Jun_g_ques;
+import Generator.Pri_g_ques;
+import Generator.Sen_g_ques;
+
+import java.util.ArrayList;
+
+public class Generate_paper {
+    public static ArrayList<Question> g_paper(int num,String type) {
+        ArrayList<Question> result = new ArrayList<>();
+        G_ques generator;
+        switch (type){
+            case "小学":{
+                generator=new Pri_g_ques();
+                break;
+            }
+            case "初中":{
+                generator=new Jun_g_ques();
+                break;
+            }
+            case "高中":{
+                generator=new Sen_g_ques();
+                break;
+            }
+            default:{
+                generator=new Pri_g_ques();
+            }
+        }
+        for (int i=0;i<num;i++){
+            Question temp=new Question(i+1,generator.g_question(),generator.g_type());
+            temp.set_options();
+            result.add(temp);
+        }
+        return result;
+    }
+}

src/Service/User_service.java

@@ -0,0 +1,93 @@
+package Service;
+
+import Base.User;
+import java.io.*;
+import java.util.ArrayList;
+
+public class User_service {
+    private ArrayList<User> users;
+    private final String base_dir="用户/";
+
+    public User_service() {
+        if (!load_users()){
+            users=new ArrayList<>();
+        }
+    }
+
+    public String change_pwd(String email, String oldPassword, String newPassword){
+        User user=find_user(email);
+        if (user == null) {
+            return "用户不存在";
+        }
+        if (!user.get_password().equals(oldPassword)) {
+            return "原密码不正确";
+        }
+        if (oldPassword.equals(newPassword)){
+            return "新密码与原密码一致";
+        }
+        if (!User.check_password(newPassword)) {
+            return "密码长6-20位，至少包含大小写字母和数字";
+        }
+        user.set_password(newPassword);
+        if (save_users()) {
+            return "修改成功";
+        }
+        return "修改失败";
+    }
+
+    public User find_user(String email){
+        for (User user : users) {
+            if (user.get_email().equals(email)) {
+                return user;
+            }
+        }
+        return null;
+    }
+
+    public boolean save_users(){
+        File baseDir = new File(base_dir);
+        if (!baseDir.exists()) {
+            if (!baseDir.mkdirs()){
+                return false;
+            }
+        }
+        String file_path=base_dir+"用户信息.txt";
+        try (PrintWriter writer = new PrintWriter(new FileWriter(file_path))) {
+            for (int i = 0; i < users.size(); i++) {
+                writer.println(users.get(i).get_email()+" "+users.get(i).get_password());
+                if (i < users.size() - 1) {
+                    writer.println();
+                }
+            }
+            return true;
+        } catch (IOException e) {
+            return false;
+        }
+    }
+
+    public boolean load_users(){
+        users=new ArrayList<>();
+        String file_path=base_dir+"用户信息.txt";
+        File file=new File(file_path);
+        if (file.exists()){
+            try (BufferedReader reader = new BufferedReader(new FileReader(file))) {
+                String line;
+                while ((line = reader.readLine()) != null) {
+                    if (!line.trim().isEmpty()) {
+                        String l=line.trim();
+                        String[] parts=l.split(" ");
+                        if (parts.length==2){
+                            User temp=new User(parts[0]);
+                            temp.set_password(parts[1]);
+                            users.add(temp);
+                        }
+                    }
+                }
+                return true;
+            } catch (IOException e) {
+                return false;
+            }
+        }
+        return false;
+    }
+}