优化Spring Boot响应式服务中多外部API集成：异步调用与资源管理

// 示例：定义外部API服务接口
public interface ExternalApiService {
    Mono<Map<String, Object>> fetchData();
}

// 示例：特定外部API的实现
@Service
public class ApiAClient implements ExternalApiService {
    private final WebClient webClient; // Spring WebClient for reactive HTTP calls
    // ... 其他配置，如API Key, 限流器等

    public ApiAClient(WebClient.Builder webClientBuilder) {
        this.webClient = webClientBuilder.baseUrl("https://api.example.com/a").build();
    }

    @Override
    public Mono<Map<String, Object>> fetchData() {
        return webClient.get()
                .uri("/data")
                .retrieve()
                .bodyToMono(new ParameterizedTypeReference<Map<String, Object>>() {})
                .doOnError(e -> System.err.println("Error calling API A: " + e.getMessage()))
                .onErrorResume(e -> {
                    // 自定义错误处理，例如返回默认值或记录日志
                    System.err.println("API A failed, returning default data.");
                    return Mono.just(Map.of("status", "error", "message", "API A unavailable"));
                })
                .timeout(Duration.ofSeconds(5)) // 设置超时
                .retryWhen(Retry.backoff(3, Duration.ofSeconds(2)).maxBackoff(Duration.ofSeconds(10))); // 重试策略
    }
}

@Service
public class DataAggregatorService {
    private final ApiAClient apiAClient;
    private final ApiBClient apiBClient;
    // ... 其他API客户端

    public DataAggregatorService(ApiAClient apiAClient, ApiBClient apiBClient) {
        this.apiAClient = apiAClient;
        this.apiBClient = apiBClient;
    }

    public Mono<Map<String, Object>> aggregateAllData() {
        Mono<Map<String, Object>> dataA = apiAClient.fetchData();
        Mono<Map<String, Object>> dataB = apiBClient.fetchData();
        // ... 其他API的Mono

        // 使用 Mono.zip 聚合所有API的响应
        return Mono.zip(dataA, dataB /*, ...其他Mono */)
                   .map(tuple -> {
                       Map<String, Object> aggregatedResult = new HashMap<>();
                       aggregatedResult.put("apiAData", tuple.getT1());
                       aggregatedResult.put("apiBData", tuple.getT2());
                       // ... 组合其他数据

                       // 进一步处理和转换，生成最终的JSON结构
                       return aggregatedResult;
                   })
                   .doOnError(e -> System.err.println("Aggregation failed: " + e.getMessage()))
                   .onErrorResume(e -> {
                       // 聚合层面的错误处理，例如返回一个包含部分数据或错误信息的响应
                       return Mono.just(Map.of("overallStatus", "error", "message", "Failed to aggregate all data"));
                   });
    }
}