处理REST API动态响应：基于JSON结构动态解析不同数据类型

import com.fasterxml.jackson.annotation.JsonAlias;
import lombok.EqualsAndHashCode;
import lombok.Getter;
import lombok.Setter;
import lombok.ToString;

// 错误响应DTO
@Getter
@Setter
@ToString
@EqualsAndHashCode
public class ZohoError {
  private String message;
  @JsonAlias("errorcode")
  private String errorCode;
  @JsonAlias("Response status")
  private int responseStatus;
}

// 成功响应中的单个记录DTO
@Getter
@Setter
@ToString
@EqualsAndHashCode
public class Leave {
  private String id;
  private String employeeName;
  private String leaveType;
  // ... 其他字段
}

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.core.type.TypeReference;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

import java.util.Collections;
import java.util.List;

@Service
public class ThirdPartyApiService {

    private final RestTemplate restTemplate;
    private final ObjectMapper objectMapper; // 注入或创建ObjectMapper实例

    public ThirdPartyApiService(RestTemplate restTemplate, ObjectMapper objectMapper) {
        this.restTemplate = restTemplate;
        this.objectMapper = objectMapper;
    }

    public List<Leave> getLeaveRecords(String uri) {
        HttpHeaders httpHeaders = new HttpHeaders();
        // ... 添加必要的HTTP头

        HttpEntity<Void> request = new HttpEntity<>(httpHeaders);

        // 1. 获取原始响应字符串
        ResponseEntity<String> response = restTemplate.exchange(uri, HttpMethod.GET, request, String.class);
        String responseBody = response.getBody();

        if (responseBody == null || responseBody.isEmpty()) {
            return Collections.emptyList();
        }

        try {
            // 2. 将响应字符串解析为JsonNode
            JsonNode rootNode = objectMapper.readTree(responseBody);

            // 3. 判断JSON结构：
            // 假设错误响应总是包含 "errorCode" 字段，而成功列表响应是一个JSON数组。
            // 这是一个基于业务规则的判断，需要根据实际API响应结构来确定。
            if (rootNode.has("errorCode") || rootNode.has("message") && rootNode.has("Response status")) {
                // 看起来是错误响应
                ZohoError zohoError = objectMapper.readValue(responseBody, ZohoError.class);
                System.err.println("API返回错误: " + zohoError.getMessage() + " (Code: " + zohoError.getErrorCode() + ")");
                return Collections.emptyList(); // 或者抛出自定义异常
            } else if (rootNode.isArray()) {
                // 看起来是列表响应
                // 使用TypeReference来处理泛型列表的反序列化
                return objectMapper.readValue(responseBody, new TypeReference<List<Leave>>() {});
            } else {
                // 未知响应结构，可能是单个对象而不是列表，或者其他意外情况
                System.err.println("API返回未知结构: " + responseBody);
                return Collections.emptyList();
            }
        } catch (Exception e) {
            System.err.println("解析API响应失败: " + e.getMessage());
            // 记录日志，并根据业务需求处理异常
            return Collections.emptyList();
        }
    }
}