java/project（期末项目报告）/CrawlerMain2/src/command/WeatherCrawlCommand.java

package command;

import controller.CrawlerContext;
import crawler.WeatherCrawler;
import exception.CrawlerException;
import exception.NetworkException;
import exception.ParseException;
import model.Weather;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import util.DataUtil;

import java.io.IOException;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

public class WeatherCrawlCommand implements CrawlCommand {
    private final CrawlerContext context;
    private List<Weather> weatherList;
    private List<Weather> oldWeatherList;

    private static final Logger logger = LoggerFactory.getLogger(WeatherCrawlCommand.class);

    public WeatherCrawlCommand(CrawlerContext context) {
        this.context = context;
    }

    @Override
    public void execute() throws ParseException, NetworkException, CrawlerException, IOException {
        oldWeatherList = DataUtil.importJson("weather.json", Weather.class);
        logger.info("导入历史天气数据：{}条", oldWeatherList.size());

        // 第四点：增量抓取，过滤重复城市
        Set<String> existCities = DataUtil.getExistWeatherCities("weather.json");

        context.setCrawlerStrategy(new WeatherCrawler());
        weatherList = (List<Weather>) context.executeCrawl();

        weatherList = weatherList.stream()
                .filter(weather -> !existCities.contains(weather.getCity()))
                .collect(Collectors.toList());

        weatherList.addAll(oldWeatherList);

        DataUtil.addAll("天气数据.txt", weatherList);
        DataUtil.exportJson("weather.json", weatherList);
        logger.info("天气爬取完成，本次新增：{}条", weatherList.size() - oldWeatherList.size());
    }

    public List<Weather> getResult() {
        return weatherList;
    }
}