Send HTTP request and handle response using HttpClient in Java 11

Title: Sending HTTP requests and handling responses using HttpClient in Java 11

Introduction:
In modern Internet applications, HTTP communication with other servers is a very common task. Java provides some built-in tools that can help us achieve this goal, the latest and recommended among which is the HttpClient class introduced in Java 11. This article will introduce how to use HttpClient in Java 11 to send HTTP requests and process responses, helping readers better understand and master this powerful tool.

1. Create HttpClient object
   To use the HttpClient class to send HTTP requests, you first need to create an HttpClient object. HttpClient is a thread-safe class that can be shared and reused in different parts of the application. The following is a sample code to create an HttpClient object:

import java.net.http.HttpClient;

public class Main {
    public static void main(String[] args) {
        HttpClient httpClient = HttpClient.newHttpClient();
        
        // TODO: 发送HTTP请求并处理响应
    }
}

2. Send a GET request
   Sending an HTTP GET request is the most basic operation. The following is an example of sending a GET request and processing the response:

import java.net.URI;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.net.http.HttpHeaders;

public class Main {
    public static void main(String[] args) {
        HttpClient httpClient = HttpClient.newHttpClient();
        
        HttpRequest httpRequest = HttpRequest.newBuilder()
            .uri(URI.create("http://api.example.com/data"))
            .GET()
            .build();
        
        try {
            HttpResponse<String> httpResponse = httpClient.send(httpRequest, HttpResponse.BodyHandlers.ofString());
            
            int statusCode = httpResponse.statusCode();
            HttpHeaders headers = httpResponse.headers();
            String body = httpResponse.body();
            
            System.out.println("Response Code: " + statusCode);
            System.out.println("Response Headers: " + headers);
            System.out.println("Response Body: " + body);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

3. Send POST request
   In addition to sending GET request, we can also send POST request and pass the request body. Here is an example of sending a POST request and processing the response:

import java.net.URI;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.net.http.HttpHeaders;
import java.net.http.HttpRequest.BodyPublishers;

public class Main {
    public static void main(String[] args) {
        HttpClient httpClient = HttpClient.newHttpClient();
        
        String requestBody = "username=admin&password=123456";
        
        HttpRequest httpRequest = HttpRequest.newBuilder()
            .uri(URI.create("http://api.example.com/login"))
            .header("Content-Type", "application/x-www-form-urlencoded")
            .POST(BodyPublishers.ofString(requestBody))
            .build();
        
        try {
            HttpResponse<String> httpResponse = httpClient.send(httpRequest, HttpResponse.BodyHandlers.ofString());
            
            int statusCode = httpResponse.statusCode();
            HttpHeaders headers = httpResponse.headers();
            String body = httpResponse.body();
            
            System.out.println("Response Code: " + statusCode);
            System.out.println("Response Headers: " + headers);
            System.out.println("Response Body: " + body);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Conclusion:
This article explains how to send an HTTP request and process the response using the HttpClient class in Java 11. Through the sample code, we can see that the HttpClient class provides a very concise and convenient API to communicate with other servers. Readers can combine other functions of the HttpClient class to implement more complex HTTP request and response processing according to their specific needs. I hope this article can help readers better learn and apply the HttpClient class in Java 11.

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