If you are using Java 11’s HttpClient and want to log request and response details, you can achieve this by implementing a custom utility. Java 11’s HttpClient provides flexibility to log and inspect both requests and responses using its APIs. Here’s how you can log them:

Full Implementation for Logging Request and Response

Below is an example that demonstrates logging details such as HTTP headers, request body, response status, response headers, and response body.

package org.kodejava.net.http;

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.time.Duration;

public class HttpClientLogger {

   public static void main(String[] args) {
      try {
         // Create a sample HTTP GET request
         HttpClient httpClient = HttpClient.newHttpClient();

         HttpRequest request = HttpRequest.newBuilder()
                 .uri(URI.create("https://jsonplaceholder.typicode.com/posts/1"))
                 .GET()
                 .header("Accept", "application/json")
                 .timeout(Duration.ofSeconds(10))
                 .build();

         // Log Request Details
         logRequestDetails(request);

         // Send the request and receive a response
         HttpResponse<String> response = httpClient.send(request,
                 HttpResponse.BodyHandlers.ofString());

         // Log Response Details
         logResponseDetails(response);

      } catch (Exception e) {
         e.printStackTrace();
      }
   }

   private static void logRequestDetails(HttpRequest request) {
      System.out.println("---- HTTP Request Details ----");
      System.out.println("Method: " + request.method());
      System.out.println("URI: " + request.uri());
      System.out.println("Headers: " + request.headers().map());
      request.bodyPublisher().ifPresentOrElse(
              bodyPublisher -> {
                 System.out.println("Request Body: (BodyPublisher details not directly accessible, consider passing it explicitly)");
              },
              () -> System.out.println("Request Body: No body")
      );
      System.out.println("-------------------------------");
   }

   private static void logResponseDetails(HttpResponse<String> response) {
      System.out.println("---- HTTP Response Details ----");
      System.out.println("Status Code: " + response.statusCode());
      System.out.println("Headers: " + response.headers().map());
      System.out.println("Body: " + response.body());
      System.out.println("--------------------------------");
   }
}

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Explanation of the Code

1. Setting up HttpClient:
   • We create a HttpClient instance using HttpClient.newHttpClient().
2. Building the HttpRequest:
   • Use the HttpRequest.Builder to construct the request. This includes setting the URI, method, headers, and a timeout.
3. Logging HTTP Request Details:
   • Log details of the request by accessing:
     • HTTP Method: HttpRequest::method
     • URI: HttpRequest::uri
     • Headers: HttpRequest::headers
     • The request body can be logged if you manually supply it during the request creation since BodyPublisher doesn’t provide a content preview.
4. Sending the Request:
   • Use HttpClient::send to perform the HTTP operation, and specify HttpResponse.BodyHandlers.ofString() to read the response as a string.
5. Logging HTTP Response Details:
   • Log response information:
     • Status Code: HttpResponse::statusCode
     • Headers: HttpResponse::headers
     • Body: HttpResponse::body

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Notes

1. POST/PUT Requests with a Body:
   • If you are sending POST or PUT requests that include a body (e.g., JSON or a form), you should explicitly log the body content when building the request. Example:

     HttpRequest request = HttpRequest.newBuilder()
           .uri(URI.create("https://jsonplaceholder.typicode.com/posts"))
           .POST(HttpRequest.BodyPublishers.ofString("{\"key\":\"value\"}"))
           .header("Content-Type", "application/json")
           .build();
     

     To log the request body, simply store it in a separate variable and print it in logRequestDetails.

2. Production Logging:

   • Avoid directly printing details to the console in production.
   • Use proper logging libraries like SLF4J with an implementation (e.g., Logback or Log4j) to write logs at different levels like DEBUG, INFO, ERROR, etc.
3. Sensitive Data:
   • Avoid logging sensitive details like authentication headers or personal data (e.g., Authorization tokens, passwords).

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This approach provides a reusable template for logging HTTP requests and responses while using the Java 11+ HttpClient.