Java advanced: Laboratory 3, Task4: class GroupFileManager

GroupFileManager.java

package ua.inf.iwanoff.java.advanced.lab3.service;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.json.JettisonMappedXmlDriver;
import com.thoughtworks.xstream.security.AnyTypePermission;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.json.JSONArray;
import org.json.JSONObject;
import ua.inf.iwanoff.java.advanced.lab3.model.AcademicGroup;
import ua.inf.iwanoff.java.advanced.lab3.model.Student;

import java.io.IOException;
import java.io.PrintWriter;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class GroupFileManager {
    private static final Logger logger = LogManager.getLogger(GroupFileManager.class);

    // --- 1. Text File (Stream API) ---

    public static void writeToText(AcademicGroup group, String filename) {
        logger.info("Writing group to TEXT file: " + filename);
        try (PrintWriter writer = new PrintWriter(filename, StandardCharsets.UTF_8)) {
            writer.println(group.getGroupName());
            group.getStudents()
                    .forEach(s -> writer.println(s.getName() + ";" + s.getAge() + ";" + s.getAverageGrade()));
        } catch (IOException e) {
            logger.error("Error writing text file", e);
        }
    }

    public static AcademicGroup readFromText(String filename) {
        logger.info("Reading group from TEXT file: " + filename);
        try (Stream<String> lines = Files.lines(Paths.get(filename), StandardCharsets.UTF_8)) {
            List<String> list = lines.collect(Collectors.toList());
            if (list.isEmpty())
                return null;

            String groupName = list.get(0);
            List<Student> students = list.stream()
                    .skip(1)
                    .map(line -> {
                        String[] parts = line.split(";");
                        return new Student(parts[0], Integer.parseInt(parts[1]), Double.parseDouble(parts[2]));
                    })
                    .collect(Collectors.toList());

            return new AcademicGroup(groupName, students);
        } catch (IOException e) {
            logger.error("Error reading text file", e);
            return null;
        }
    }

    // --- 2. XML (XStream) ---

    public static void serializeToXML(AcademicGroup group, String filename) {
        logger.info("Serializing group to XML: " + filename);
        XStream xStream = new XStream();
        xStream.alias("group", AcademicGroup.class);
        xStream.alias("student", Student.class);

        try (PrintWriter writer = new PrintWriter(filename, StandardCharsets.UTF_8)) {
            writer.print(xStream.toXML(group));
        } catch (IOException e) {
            logger.error("Error writing XML", e);
        }
    }

    public static AcademicGroup deserializeFromXML(String filename) {
        logger.info("Deserializing group from XML: " + filename);
        XStream xStream = new XStream();
        xStream.addPermission(AnyTypePermission.ANY);
        xStream.alias("group", AcademicGroup.class);
        xStream.alias("student", Student.class);

        try {
            return (AcademicGroup) xStream.fromXML(Paths.get(filename).toFile());
        } catch (Exception e) {
            logger.error("Error reading XML", e);
            return null;
        }
    }

    // --- 3. JSON (XStream) ---

    public static void serializeToJSON_XStream(AcademicGroup group, String filename) {
        logger.info("Serializing group to JSON (XStream): " + filename);
        XStream xStream = new XStream(new JettisonMappedXmlDriver());
        xStream.alias("group", AcademicGroup.class);
        xStream.alias("student", Student.class);

        try (PrintWriter writer = new PrintWriter(filename, StandardCharsets.UTF_8)) {
            writer.print(xStream.toXML(group));
        } catch (IOException e) {
            logger.error("Error writing JSON (XStream)", e);
        }
    }

    public static AcademicGroup deserializeFromJSON_XStream(String filename) {
        logger.info("Deserializing group from JSON (XStream): " + filename);
        XStream xStream = new XStream(new JettisonMappedXmlDriver());
        xStream.addPermission(AnyTypePermission.ANY);
        xStream.alias("group", AcademicGroup.class);
        xStream.alias("student", Student.class);

        try {
            return (AcademicGroup) xStream.fromXML(Paths.get(filename).toFile());
        } catch (Exception e) {
            logger.error("Error reading JSON (XStream)", e);
            return null;
        }
    }

    // --- 4. JSON (Org.json) - Завдання 1.5 ---

    public static void writeJsonOrg(AcademicGroup group, String filename) {
        logger.info("Writing group to JSON (org.json): " + filename);

        // Створення JSON структури
        JSONObject jsonGroup = new JSONObject();
        jsonGroup.put("groupName", group.getGroupName());

        JSONArray jsonStudents = new JSONArray();
        for (Student s : group.getStudents()) {
            JSONObject jsonStudent = new JSONObject();
            jsonStudent.put("name", s.getName());
            jsonStudent.put("age", s.getAge());
            jsonStudent.put("avg", s.getAverageGrade());
            jsonStudents.put(jsonStudent);
        }
        jsonGroup.put("students", jsonStudents);

        try (PrintWriter writer = new PrintWriter(filename, StandardCharsets.UTF_8)) {
            // indentFactor=2 для красивого форматування
            writer.print(jsonGroup.toString(2));
        } catch (IOException e) {
            logger.error("Error writing JSON (org.json)", e);
        }
    }

    public static AcademicGroup readJsonOrg(String filename) {
        logger.info("Reading group from JSON (org.json): " + filename);
        try {
            String content = new String(Files.readAllBytes(Paths.get(filename)), StandardCharsets.UTF_8);
            JSONObject jsonGroup = new JSONObject(content);

            String groupName = jsonGroup.getString("groupName");
            JSONArray jsonStudents = jsonGroup.getJSONArray("students");
            List<Student> students = new ArrayList<>();

            for (int i = 0; i < jsonStudents.length(); i++) {
                JSONObject obj = jsonStudents.getJSONObject(i);
                students.add(new Student(
                        obj.getString("name"),
                        obj.getInt("age"),
                        obj.getDouble("avg")));
            }

            return new AcademicGroup(groupName, students);
        } catch (IOException e) {
            logger.error("Error reading JSON (org.json)", e);
            return null;
        }
    }
}