Gson反序列化静态字段为null的解决方案

{
  "date": "2022-12-08",
  "explanation": "...",
  "hdurl": "https://apod.nasa.gov/apod/image/2212/art001e002132.jpg",
  "media_type": "image",
  "service_version": "v1",
  "title": "Orion and the Ocean of Storms",
  "url": "https://apod.nasa.gov/apod/image/2212/art001e002132_apod1024.jpg"
}

package space;

public class Objects {
    private static String url; // 问题：字段被声明为static，且字段名与JSON属性名不完全匹配

    public static String geturl() {
        return url;
    }
    public void sethdurl(String url) { // 问题：尝试设置静态字段，方法名与字段名不一致
        Objects.url = url;
    }
    // ... 其他方法
}

package space;

// 为了清晰起见，我们将类名从Objects改为ApodResponse，更具描述性
public class ApodResponse {
    private String hdurl; // 修正：移除static关键字，字段名与JSON属性名一致

    // 修正：提供符合Java Bean规范的公共getter方法
    public String getHdurl() {
        return hdurl;
    }

    // 修正：提供符合Java Bean规范的公共setter方法
    public void setHdurl(String hdurl) {
        this.hdurl = hdurl;
    }

    // 如果JSON中还有其他属性，例如"title", "explanation"等，可以继续添加对应的字段和方法
    // private String title;
    // public String getTitle() { return title; }
    // public void setTitle(String title) { this.title = title; }
}

import com.google.gson.Gson;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.net.http.HttpResponse.BodyHandlers;

public class ApodClient {

    public static void main(String[] args) throws IOException, InterruptedException, URISyntaxException {
        // 假设我们已经获取到了JSON字符串，这里为了演示直接使用一个示例JSON
        // 实际应用中，这段JSON会通过HTTP请求获取
        String jsonResponse = "{\n" +
                              "  \"date\": \"2022-12-08\",\n" +
                              "  \"explanation\": \"A camera on board the uncrewed Orion spacecraft captured this view on December 5 as Orion approached its return powered flyby of the Moon.\",\n" +
                              "  \"hdurl\": \"https://apod.nasa.gov/apod/image/2212/art001e002132.jpg\",\n" +
                              "  \"media_type\": \"image\",\n" +
                              "  \"service_version\": \"v1\",\n" +
                              "  \"title\": \"Orion and the Ocean of Storms\",\n" +
                              "  \"url\": \"https://apod.nasa.gov/apod/image/2212/art001e002132_apod1024.jpg\"\n" +
                              "}";

        System.out.println("--- 原始JSON响应 ---");
        System.out.println(jsonResponse);

        Gson gson = new Gson();
        // 使用修正后的ApodResponse类进行反序列化
        ApodResponse apodObject = gson.fromJson(jsonResponse, ApodResponse.class);

        // 现在可以正确地从对象中获取hdurl
        String hdUrlResult = apodObject.getHdurl();
        System.out.println("\n--- 提取的HD URL ---");
        System.out.println(hdUrlResult); // 将输出：https://apod.nasa.gov/apod/image/2212/art001e002132.jpg

        // 实际的HTTP请求代码（如果需要，可以取消注释并运行）
        /*
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest getRequest = HttpRequest.newBuilder()
            .uri(new URI("https://api.nasa.gov/planetary/apod?api_key=vtBLyZ1ON5hZybof2EfuXHWgdcNAXh9DdZrZAOvK")) // 示例API Key
            .build();
        HttpResponse<String> response = client.send(getRequest, BodyHandlers.ofString());
        System.out.println("\n--- 实际API响应 ---");
        System.out.println(response.body());
        ApodResponse actualApodObject = gson.fromJson(response.body(), ApodResponse.class);
        System.out.println("\n--- 实际提取的HD URL ---");
        System.out.println(actualApodObject.getHdurl());
        */
    }
}