Spring Boot多线程实现异步发送Http离线请求数据至服务端流程

首先，需要在Spring Boot的配置类中创建一个线程池来处理异步请求。可以使用Java自带的线程池，也可以使用Spring Boot提供的线程池。

然后，在需要异步发送Http请求的方法上添加@Async注解，表示这是一个异步方法。在方法中使用Java的HttpURLConnection或者其他Http客户端库发送请求并获取返回结果。

最后，需要在异步发送请求的方法调用处使用CompletableFuture来处理异步结果。可以使用CompletableFuture的回调方法来处理请求成功和失败的情况，并返回结果给调用方。

以下是一个简单的示例代码：

@Configuration
@EnableAsync
public class AsyncConfig {
    @Bean
    public Executor asyncExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(10);
        executor.setMaxPoolSize(20);
        executor.setQueueCapacity(100);
        executor.setThreadNamePrefix("AsyncThread-");
        executor.initialize();
        return executor;
    }
}

@Service
public class HttpService {
    @Async
    public CompletableFuture<String> sendHttpRequest(String url, String requestBody) {
        try {
            URL urlObj = new URL(url);
            HttpURLConnection conn = (HttpURLConnection) urlObj.openConnection();
            conn.setRequestMethod("POST");
            conn.setRequestProperty("Content-Type", "application/json");
            conn.setDoOutput(true);
            OutputStream os = conn.getOutputStream();
            os.write(requestBody.getBytes());
            os.flush();
            os.close();
            int responseCode = conn.getResponseCode();
            if (responseCode == HttpURLConnection.HTTP_OK) {
                BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
                String inputLine;
                StringBuilder response = new StringBuilder();
                while ((inputLine = in.readLine()) != null) {
                    response.append(inputLine);
                }
                in.close();
                return CompletableFuture.completedFuture(response.toString());
            } else {
                return CompletableFuture.failedFuture(new RuntimeException("Http request failed with response code: " + responseCode));
            }
        } catch (Exception e) {
            return CompletableFuture.failedFuture(e);
        }
    }
}

@Service
public class MyService {
    @Autowired
    private HttpService httpService;

    public void doSomething() {
        String requestBody = "example request body";
        String url = "http://example.com/api";
        CompletableFuture<String> future = httpService.sendHttpRequest(url, requestBody);
        future.whenComplete((result, ex) -> {
            if (ex != null) {
                // handle exception
            } else {
                // handle success result
            }
        });
    }
}