java/w4/GreenlandHistoryWeather.java

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.time.LocalDate;
import java.time.format.DateTimeFormatter;

public class GreenlandHistoryWeather {

    public static void main(String[] args) {
        System.out.println("🚀 开始获取格陵兰岛历史天气数据...");

        // --- 配置区域 ---
        double latitude = 64.18;   // 努克 (Nuuk) 纬度
        double longitude = -51.69; // 努克 (Nuuk) 经度
        
        // --- 设定历史时间段 ---
        // 这里是你之前设置的 2025 年 1 月
        LocalDate startDate = LocalDate.of(2025, 12, 1);   
        LocalDate endDate = LocalDate.of(2026, 1, 31);    
        
        String dateStartStr = startDate.format(DateTimeFormatter.ISO_LOCAL_DATE);
        String dateEndStr = endDate.format(DateTimeFormatter.ISO_LOCAL_DATE);
        
        System.out.println("📅 查询时间段: " + dateStartStr + " 至 " + dateEndStr);
        System.out.println("📍 地点: 格陵兰岛 - 努克 (Nuuk)\n");

        // --- 构建 API URL ---
        // ⚠️ 关键修改：使用 archive-api.open-meteo.com/v1/archive 专门获取历史数据
        String apiUrl = String.format(
            "https://archive-api.open-meteo.com/v1/archive?latitude=%f&longitude=%f" +
            "&start_date=%s&end_date=%s" +
            "&daily=temperature_2m_max,temperature_2m_min,precipitation_sum" +
            "&timezone=auto",
            latitude, longitude, dateStartStr, dateEndStr
        );

        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create(apiUrl))
                .GET()
                .build();

        try {
            // 发送请求
            HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());

            if (response.statusCode() == 200) {
                String json = response.body();
                parseAndPrintHistory(json);
            } else {
                System.out.println("❌ 请求失败，状态码: " + response.statusCode());
                System.out.println("返回信息: " + response.body());
                System.out.println("\n💡 提示：如果状态码是 400，请检查日期是否超出了该站点的数据记录范围。");
            }

        } catch (Exception e) {
            System.out.println("❌ 发生网络或程序错误: ");
            e.printStackTrace();
        }
    }

    // --- 解析并打印数据 ---
    private static void parseAndPrintHistory(String json) {
        System.out.println("✅ 数据获取成功！解析结果如下：\n");
        System.out.printf("%-12s | %-10s | %-10s | %-10s%n", "日期", "最高温(°C)", "最低温(°C)", "降水(mm)");
        System.out.println("-------------------------------------------------------");

        // 【关键】API 返回的日期字段名是 "time"，不是 "date"
        String[] dates = extractArray(json, "time"); 
        
        String[] maxTemps = extractArray(json, "temperature_2m_max");
        String[] minTemps = extractArray(json, "temperature_2m_min");
        String[] precip = extractArray(json, "precipitation_sum");

        int count = Math.min(dates.length, maxTemps.length);
        
        if (count == 0) {
            System.out.println("⚠️ 警告：未解析到数据。可能是该时间段无记录，或 JSON 结构变化。");
            return;
        }

        for (int i = 0; i < count; i++) {
            // 清理日期字符串两边的引号
            String dateClean = dates[i].replace("\"", ""); 
            
            System.out.printf("%-12s | %-10s | %-10s | %-10s%n", 
                dateClean, 
                maxTemps[i], 
                minTemps[i], 
                precip[i]
            );
        }
        System.out.println("-------------------------------------------------------");
        System.out.println("💡 任务完成！共获取 " + count + " 天的数据。");
    }

    // --- 辅助方法：简易 JSON 数组提取器 ---
    private static String[] extractArray(String json, String key) {
        String searchKey = "\"" + key + "\":[";
        int startIndex = json.indexOf(searchKey);
        
        // 如果找不到键，返回空数组
        if (startIndex == -1) return new String[0];
        
        startIndex += searchKey.length();
        int endIndex = json.indexOf("]", startIndex);
        
        if (endIndex == -1) return new String[0];
        
        String arrayContent = json.substring(startIndex, endIndex);
        
        // 按逗号分割，并去除可能的空白字符
        if (arrayContent.trim().isEmpty()) return new String[0];
        return arrayContent.split(",");
    }
}