java/project/ChangshaHouseCrawler.java

import java.util.*;
import java.io.*;

// ==================== 异常体系 ====================
class CrawlerException extends Exception {
    public CrawlerException(String msg) { super(msg); }
    public CrawlerException(String msg, Throwable t) { super(msg, t); }
}

class NetworkException extends CrawlerException {
    public NetworkException(String msg) { super("网络异常: " + msg); }
}

class ParseException extends CrawlerException {
    public ParseException(String msg) { super("解析异常: " + msg); }
}

class SaveException extends CrawlerException {
    public SaveException(String msg) { super("保存异常: " + msg); }
}

// ==================== 数据模型 (Model) ====================
class HouseData {
    private String title;
    private double area;
    private double price;
    private String district;
    private String source;

    public HouseData(String t, double a, double p, String d, String s) {
        title = t; area = a; price = p; district = d; source = s;
    }

    public String toCSV() {
        return String.format("\"%s\",%.1f,%.1f,\"%s\",\"%s\"", title, area, price, district, source);
    }

    public static String getCSVHeader() {
        return "标题,面积(㎡),总价(万),区域,来源";
    }

    public String getSource() { return source; }
}

// ==================== 策略模式 (Strategy) ====================
interface CrawlerStrategy {
    String getSiteName();
    List<HouseData> crawl() throws CrawlerException;
}

class LianJiaCrawler implements CrawlerStrategy {
    private Random r = new Random();
    private String[] dists = {"岳麓区", "雨花区", "天心区", "开福区", "芙蓉区"};

    public String getSiteName() { return "链家"; }

    public List<HouseData> crawl() throws CrawlerException {
        List<HouseData> list = new ArrayList<>();
        try {
            Thread.sleep(300);
            for (int i = 0; i < 10; i++) {
                list.add(new HouseData("链家房源" + (i+1), 
                    60 + r.nextDouble() * 100, 
                    80 + r.nextDouble() * 150, 
                    dists[r.nextInt(5)], "链家"));
            }
            return list;
        } catch (InterruptedException e) {
            throw new CrawlerException("被中断", e);
        }
    }
}

class AnJuKeCrawler implements CrawlerStrategy {
    private Random r = new Random();
    private String[] dists = {"岳麓区", "雨花区", "天心区", "开福区", "芙蓉区"};

    public String getSiteName() { return "安居客"; }

    public List<HouseData> crawl() throws CrawlerException {
        List<HouseData> list = new ArrayList<>();
        try {
            Thread.sleep(250);
            for (int i = 0; i < 8; i++) {
                list.add(new HouseData("安居客房源" + (i+1), 
                    70 + r.nextDouble() * 80, 
                    70 + r.nextDouble() * 120, 
                    dists[r.nextInt(5)], "安居客"));
            }
            return list;
        } catch (InterruptedException e) {
            throw new CrawlerException("被中断", e);
        }
    }
}

class BeiKeCrawler implements CrawlerStrategy {
    private Random r = new Random();
    private String[] dists = {"岳麓区", "雨花区", "天心区", "开福区", "芙蓉区"};

    public String getSiteName() { return "贝壳"; }

    public List<HouseData> crawl() throws CrawlerException {
        List<HouseData> list = new ArrayList<>();
        try {
            Thread.sleep(350);
            for (int i = 0; i < 12; i++) {
                list.add(new HouseData("贝壳房源" + (i+1), 
                    80 + r.nextDouble() * 90, 
                    90 + r.nextDouble() * 130, 
                    dists[r.nextInt(5)], "贝壳"));
            }
            return list;
        } catch (InterruptedException e) {
            throw new CrawlerException("被中断", e);
        }
    }
}

// ==================== Command模式 ====================
interface Command {
    void execute();
}

class CrawlCommand implements Command {
    private CrawlerStrategy strategy;
    private List<HouseData> dataList;
    private View view;

    public CrawlCommand(CrawlerStrategy s, List<HouseData> d, View v) {
        strategy = s; dataList = d; view = v;
    }

    public void execute() {
        view.showMessage("正在爬取 " + strategy.getSiteName() + "...");
        try {
            List<HouseData> result = strategy.crawl();
            dataList.addAll(result);
            view.showSuccess(strategy.getSiteName() + ": " + result.size() + " 条");
        } catch (CrawlerException e) {
            view.showError(strategy.getSiteName() + " 失败: " + e.getMessage());
        }
    }
}

class SaveCommand implements Command {
    private List<HouseData> dataList;
    private View view;

    public SaveCommand(List<HouseData> d, View v) { dataList = d; view = v; }

    public void execute() {
        view.showMessage("正在保存数据...");
        try (PrintWriter w = new PrintWriter("changsha_house.csv")) {
            w.println(HouseData.getCSVHeader());
            for (HouseData d : dataList) w.println(d.toCSV());
            view.showSuccess("已保存到 changsha_house.csv");
        } catch (FileNotFoundException e) {
            view.showError("保存失败: " + e.getMessage());
        }
    }
}

class DisplayCommand implements Command {
    private List<HouseData> dataList;
    private View view;

    public DisplayCommand(List<HouseData> d, View v) { dataList = d; view = v; }

    public void execute() {
        view.displayData(dataList);
    }
}

// ==================== 视图 (View) ====================
class View {
    public void showWelcome() {
        System.out.println("╔════════════════════════════════════╗");
        System.out.println("║      长沙房价爬虫系统 v1.0         ║");
        System.out.println("╚════════════════════════════════════╝");
        System.out.println();
    }

    public void showMenu() {
        System.out.println("请选择操作:");
        System.out.println("1. 爬取所有网站");
        System.out.println("2. 爬取链家");
        System.out.println("3. 爬取安居客");
        System.out.println("4. 爬取贝壳");
        System.out.println("5. 显示数据");
        System.out.println("6. 保存数据");
        System.out.println("0. 退出");
        System.out.print("输入选项: ");
    }

    public void showMessage(String msg) {
        System.out.println("[*] " + msg);
    }

    public void showSuccess(String msg) {
        System.out.println("[✓] " + msg);
    }

    public void showError(String msg) {
        System.err.println("[✗] " + msg);
    }

    public void displayData(List<HouseData> data) {
        if (data.isEmpty()) {
            System.out.println("暂无数据");
            return;
        }
        System.out.println("\n数据预览 (" + data.size() + "条):");
        System.out.println(HouseData.getCSVHeader());
        int count = Math.min(5, data.size());
        for (int i = 0; i < count; i++) {
            System.out.println(data.get(i).toCSV());
        }
        if (data.size() > 5) System.out.println("... 还有 " + (data.size()-5) + " 条");
    }
}

// ==================== 控制器 (Controller) ====================
class Controller {
    private View view;
    private List<HouseData> dataList;
    private List<CrawlerStrategy> strategies;

    public Controller(View v) {
        view = v;
        dataList = new ArrayList<>();
        strategies = Arrays.asList(new LianJiaCrawler(), new AnJuKeCrawler(), new BeiKeCrawler());
    }

    public void run() {
        view.showWelcome();
        Scanner scanner = new Scanner(System.in);
        while (true) {
            view.showMenu();
            try {
                int choice = Integer.parseInt(scanner.nextLine().trim());
                Command command = null;

                switch (choice) {
                    case 1:
                        for (CrawlerStrategy s : strategies) {
                            new CrawlCommand(s, dataList, view).execute();
                        }
                        break;
                    case 2:
                        command = new CrawlCommand(new LianJiaCrawler(), dataList, view);
                        break;
                    case 3:
                        command = new CrawlCommand(new AnJuKeCrawler(), dataList, view);
                        break;
                    case 4:
                        command = new CrawlCommand(new BeiKeCrawler(), dataList, view);
                        break;
                    case 5:
                        command = new DisplayCommand(dataList, view);
                        break;
                    case 6:
                        command = new SaveCommand(dataList, view);
                        break;
                    case 0:
                        System.out.println("再见!");
                        return;
                    default:
                        view.showError("无效选项");
                }

                if (command != null) {
                    command.execute();
                }
                System.out.println();
            } catch (NumberFormatException e) {
                view.showError("请输入数字");
            }
        }
    }
}

// ==================== 主程序 (CLI入口) ====================
public class ChangshaHouseCrawler {
    public static void main(String[] args) {
        View view = new View();
        Controller controller = new Controller(view);
        controller.run();
    }
}