RestTemplate之java.io.IOException:stream closed 异常的原因及处理

springboot集成resttemplate时想打印相关请求日志，设置统一的拦截器

拦截器相关代码：

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpRequest;
import org.springframework.http.client.ClientHttpRequestExecution;
import org.springframework.http.client.ClientHttpRequestInterceptor;
import org.springframework.http.client.ClientHttpResponse;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public class RestTemplateLogRecordInterceptor implements ClientHttpRequestInterceptor {

    private final static Logger LOGGER = LoggerFactory.getLogger(RestTemplateLogRecordInterceptor.class);

    @Override
    public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) throws IOException {
        traceRequest(request, body);
        ClientHttpResponse response = execution.execute(request, body);
        traceResponse(response);
        return response;
    }

    private void traceRequest(HttpRequest request, byte[] body) throws IOException {
        LOGGER.debug("===========================request begin================================================");
        LOGGER.debug("URI         : {}", request.getURI());
        LOGGER.debug("Method      : {}", request.getMethod());
        LOGGER.debug("Headers     : {}", request.getHeaders());
        LOGGER.debug("Request body: {}", new String(body, "UTF-8"));
        LOGGER.debug("==========================request end================================================");
    }

    private void traceResponse(ClientHttpResponse response) throws IOException {
        StringBuilder inputStringBuilder = new StringBuilder();
        InputStream body = response.getBody();
        try (BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(body, "UTF-8"))) {
            String line = bufferedReader.readLine();
            while (line != null) {
                inputStringBuilder.append(line);
                inputStringBuilder.append('\n');
                line = bufferedReader.readLine();
            }
        }
        LOGGER.debug("============================response begin==========================================");
        LOGGER.debug("Status code  : {}", response.getStatusCode());
        LOGGER.debug("Status text  : {}", response.getStatusText());
        LOGGER.debug("Headers      : {}", response.getHeaders());
        LOGGER.debug("Response body: {}", inputStringBuilder.toString());
        LOGGER.debug("=======================response end=================================================");
    }

}

配置resttemplate自定义bean

@Configuration
public class RestTemplateConfiguration {

    @Bean
    public RestTemplate getRestTemplate() {
        SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory();
        //motor服务有的服务响应时间较长，暂定半个小时
        factory.setReadTimeout(1800000);
        factory.setConnectTimeout(1800000);
        RestTemplate restTemplate = new RestTemplate(factory);
        restTemplate.getInterceptors().add(new RestTemplateLogRecordInterceptor());
        restTemplate.getMessageConverters().set(1, new StringHttpMessageConverter(StandardCharsets.UTF_8));
        return restTemplate;
    }

}

经过上述运行后，会出现一个问题，问题如下：

试过很多方法依旧找不到原因，不知道为啥会被close掉
解决方案：怀疑是我加了拦截器的原因，我把拦截器注释掉，则不会报该错误，思考：为啥加了拦截器就会报错呢？
只能一步一步跟踪源码，发现只要加了拦截器，inputStream中的close属性就为true,所以这也是导致为啥调取接口的时候会is close
接下来就是找到为啥inputStream中的close为啥为true?
后来某大神看了这段代码说response和request流只能读取一次，只要读取完就结束了

private void traceResponse(ClientHttpResponse response) throws IOException {
        StringBuilder inputStringBuilder = new StringBuilder();
        InputStream body = response.getBody();
        try (BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(body, "UTF-8"))) {
            String line = bufferedReader.readLine();
            while (line != null) {
                inputStringBuilder.append(line);
                inputStringBuilder.append('\n');
                line = bufferedReader.readLine();
            }
        }
        LOGGER.debug("============================response begin==========================================");
        LOGGER.debug("Status code  : {}", response.getStatusCode());
        LOGGER.debug("Status text  : {}", response.getStatusText());
        LOGGER.debug("Headers      : {}", response.getHeaders());
        LOGGER.debug("Response body: {}", inputStringBuilder.toString());
        LOGGER.debug("=======================response end=================================================");
    }

我尝试了一次，把该代码注释掉，果然不出所料，是这里的原因，那么接下来就是如何解决流只能读取一次的问题，上网搜索了一番，网上好多人解决都是说用包装类可以解决该问题，将该对象缓存下来，就不会有问题，这也就是Servlet中Fileter的实现，Filter调用链如果不包装，也可能会出现该问题

好了，现在找到解决方案了，那么如何将该返回的ClientHttpResponse 包装一下呢，又不想自己自定义，后来就在org.springframework.http.client下面找了找，发现有类似的类，但是可用的包装类都是protected的,那么就想一下既然他提供了类似的包装类，那么看他内部咋调用类似的包装类，只能一点一点看源码，最后发现一个类BufferingClientHttpRequestWrapper，但是这个也是内部调用类，外部是无法新建的，只要找调用该类的地方，发现BufferingClientHttpRequestFactory类中有相关的实现，而且这个刚好是我需要的，刚好该类是public修饰，有点意思哈，不得不惊叹作者设计模式（工厂模式）玩的很溜啊
既然找到解决方案，代码修改如下：
在RestTemplate定义的时候，将BufferingClientHttpRequestFactory传入，而非传入SimpleClientHttpRequestFactory，最终解决问题

@Bean
    public RestTemplate getRestTemplate() {
        SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory();
        BufferingClientHttpRequestFactory bufferingClientHttpRequestFactory = new BufferingClientHttpRequestFactory(factory);
        //motor服务有的服务响应时间较长，暂定半个小时
        factory.setReadTimeout(1800000);
        factory.setConnectTimeout(1800000);
        RestTemplate restTemplate = new RestTemplate(bufferingClientHttpRequestFactory);
        restTemplate.getInterceptors().add(new RestTemplateLogRecordInterceptor());
        restTemplate.getMessageConverters().set(1, new StringHttpMessageConverter(StandardCharsets.UTF_8));
        return restTemplate;
    }