@Slf4j
@Configuration
public class RestTemplateConfig {

    private static final int HTTP_CLIENT_RETRY_COUNT = 3;

    private static final int MAXIMUM_TOTAL_CONNECTION = 10;

    private static final int MAXIMUM_CONNECTION_PER_ROUTE = 5;

    private static final int CONNECTION_VALIDATE_AFTER_INACTIVITY_MS = 10 * 1000;

    /**
     * @param connectionTimeoutMs milliseconds/毫秒
     * @param readTimeoutMs milliseconds/毫秒
     * @return
     */
    public static RestTemplate createRestTemplate(int connectionTimeoutMs, int readTimeoutMs/*,ObjectMapper objectMapper*/) {

        HttpClientBuilder clientBuilder = HttpClients.custom();

        PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager();

        // 整个连接池最大连接数
        connectionManager.setMaxTotal(MAXIMUM_TOTAL_CONNECTION);
        // 设置每个路由的最大并发连接数,默认为2.
        connectionManager.setDefaultMaxPerRoute(MAXIMUM_CONNECTION_PER_ROUTE);
        // 官方推荐使用检查永久链接的可用性,而不推荐每次请求的时候才去检查 (milliseconds 毫秒)
        connectionManager.setValidateAfterInactivity(CONNECTION_VALIDATE_AFTER_INACTIVITY_MS);

        clientBuilder.setConnectionManager(connectionManager);
        //设置重连操作次数，这里设置了3次
        clientBuilder.setRetryHandler(new DefaultHttpRequestRetryHandler(HTTP_CLIENT_RETRY_COUNT, true, new ArrayList<>()) {

            @Override
            public boolean retryRequest(IOException exception, int executionCount, HttpContext context) {
                log.info("Retry request, execution count: {}, exception: {}", executionCount, exception);
                return super.retryRequest(exception, executionCount, context);
            }

        });

        // 把配置好的HttpClient放入构造器
        HttpComponentsClientHttpRequestFactory httpRequestFactory = new HttpComponentsClientHttpRequestFactory(clientBuilder.build());
        httpRequestFactory.setConnectTimeout(connectionTimeoutMs);
        httpRequestFactory.setConnectionRequestTimeout(readTimeoutMs);
        httpRequestFactory.setReadTimeout(readTimeoutMs);

        RestTemplate restTemplate = new RestTemplate(httpRequestFactory);
        // 添加自定义拦截器
        List<ClientHttpRequestInterceptor> interceptors = new ArrayList<ClientHttpRequestInterceptor>();
        interceptors.add(new LoggingClientHttpRequestInterceptor());
        restTemplate.setInterceptors(interceptors);
        //提供对传出/传入流的缓冲,可以让响应body多次读取(如果不配置,拦截器读取了Response流,再响应数据时会返回body=null)
        restTemplate.setRequestFactory(new BufferingClientHttpRequestFactory(httpRequestFactory));

       /* MappingJackson2HttpMessageConverter messageConverter = restTemplate.getMessageConverters().stream().filter(MappingJackson2HttpMessageConverter.class::isInstance)
                .map(MappingJackson2HttpMessageConverter.class::cast).findFirst().orElseThrow(() -> new RuntimeException("MappingJackson2HttpMessageConverter not found"));
        messageConverter.setObjectMapper(objectMapper);*/

       //防止响应中文乱码
        restTemplate.getMessageConverters().stream().filter(StringHttpMessageConverter.class::isInstance).map(StringHttpMessageConverter.class::cast).forEach(a -> {
            a.setWriteAcceptCharset(false);
            a.setDefaultCharset(StandardCharsets.UTF_8);
        });

        return restTemplate;
    }

    @Bean
    public RestTemplate restTemplate(){
        RestTemplate restTemplate = RestTemplateConfig.createRestTemplate(5000, 5000);
        //配置自定义的interceptor拦截器
        //使用restTemplate远程调用防止400和401导致报错而获取不到正确反馈信息
        restTemplate.setErrorHandler(new DefaultResponseErrorHandler(){
            @Override
            public void handleError(ClientHttpResponse response) throws IOException {
                if (response.getRawStatusCode() != 400 && response.getRawStatusCode() != 401){
                    super.handleError(response);
                }
            }
        });
        return restTemplate;
    }
}

@Slf4j
public class LoggingClientHttpRequestInterceptor implements ClientHttpRequestInterceptor {

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

    private void tranceRequest(HttpRequest request, byte[] body) throws UnsupportedEncodingException {
        log.debug("=========================== request begin ===========================");
        log.debug("uri : {}", request.getURI());
        log.debug("method : {}", request.getMethod());
        log.debug("headers : {}", request.getHeaders());
        log.debug("request body : {}", new String(body, "utf-8"));
        log.debug("============================ request end ============================");
    }

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