Spring Boot RestTemplate ResourceAccessException：POST 请求上的 IO 错误未能响应

使用 Spring Boot RestTemplate 进行 POST 请求时，有时会遇到 ResourceAccessException 异常，该异常表示无法响应请求的 I/O 错误。这种情况可能由于网络连接问题、服务端异常或其他原因导致。本文将介绍如何处理该异常，并提供一个案例代码来说明解决方法。

xml
    org.springframework.boot
    spring-boot-starter-web

java
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.client.RequestCallback;
import org.springframework.web.client.ResponseExtractor;
import org.springframework.web.client.RestTemplate;
import org.springframework.web.util.UriComponentsBuilder;
import java.net.URI;
public class RestTemplateExample {
    private RestTemplate restTemplate;
    public RestTemplateExample() {
        this.restTemplate = new RestTemplate();
    }
    public ResponseEntity sendPostRequest(String url, String requestBody) {
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_JSON);
        HttpEntity entity = new HttpEntity<>(requestBody, headers);
        return restTemplate.postForEntity(url, entity, String.class);
    }
}

java
public class Main {
    public static void main(String[] args) {
        RestTemplateExample example = new RestTemplateExample();
        String url = "http://example.com/api";
        String requestBody = "{\"name\":\"John\",\"age\":30}";
        try {
            ResponseEntity response = example.sendPostRequest(url, requestBody);
            System.out.println("Response: " + response.getBody());
        } catch (ResourceAccessException e) {
            System.out.println("Failed to send POST request: " + e.getMessage());
            // 处理异常，例如重试请求或记录错误日志
        }
    }
}