Send asynchronous HTTP requests and handle responses using the new HttpClient in Java 11

Use the new HttpClient in Java 11 to send asynchronous HTTP requests and process responses

In Java 11, the new HttpClient class was introduced, providing powerful functionality to send HTTP requests and process responses. Compared with the previous HttpURLConnection, the new HttpClient is easier to use and supports asynchronous operations, making it more efficient to handle concurrent requests. This article will introduce how to use the new HttpClient in Java 11 to send asynchronous HTTP requests and handle the responses.

First, we need to create an HttpClient object, which can be created through the HttpClient.newBuilder() method. When creating an HttpClient object, we can specify some specific parameters, such as timeout, proxy, etc. The following is a sample code to create an HttpClient object:

import java.net.http.HttpClient;

HttpClient httpClient = HttpClient.newBuilder()
        .connectTimeout(Duration.ofSeconds(10))
        .build();

Next, we can use the HttpClient object to send HTTP requests. In HttpClient, there are three types of requests: GET, POST and PUT. We can use the HttpRequest.newBuilder() method to create an HttpRequest object and specify the requested URL, method, request header and other parameters. The following is a sample code for sending a GET request:

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

// 发送GET请求
HttpRequest getRequest = HttpRequest.newBuilder()
        .uri(URI.create("http://example.com/api"))
        .GET()
        .build();

// 发送异步请求
httpClient.sendAsync(getRequest, HttpResponse.BodyHandlers.ofString())
        .thenApply(HttpResponse::body)
        .thenAccept(System.out::println);

In the above code, we specify the requested URL through the uri method of HttpRequest.Builder and create an HttpRequest object using the GET method. Then, we use the sendAsync method of HttpClient to send the request, and use HttpResponse.BodyHandlers.ofString() to specify how the response is handled. Finally, we used the thenApply and thenAccept methods to process the response content respectively.

In addition to GET requests, we can also send POST and PUT requests. The sample code for sending a POST request is as follows:

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

// 发送POST请求
HttpRequest postRequest = HttpRequest.newBuilder()
        .uri(URI.create("http://example.com/api"))
        .header("Content-Type", "application/json")
        .POST(BodyPublishers.ofString("{"key": "value"}"))
        .build();

// 发送异步请求
httpClient.sendAsync(postRequest, HttpResponse.BodyHandlers.ofString())
        .thenApply(HttpResponse::body)
        .thenAccept(System.out::println);

In the above code, we specify the Content-Type of the request header as application/json through the header method of HttpRequest.Builder, and create an HttpRequest object using the POST method. Then, we use the sendAsync method of HttpClient to send the request, and use HttpResponse.BodyHandlers.ofString() to specify how the response is handled. Finally, we used the thenApply and thenAccept methods to process the response content respectively.

In addition to sending requests and processing responses, HttpClient also provides some other useful methods, such as setting proxy, HTTP authentication, etc. For details, please refer to the official Java documentation.

To summarize, the new HttpClient class in Java 11 provides a more convenient and efficient way to send HTTP requests and process responses. By using the new HttpClient class, we can easily send asynchronous GET, POST, and PUT requests and use concise code to handle the responses. This enables developers to handle concurrent requests more efficiently and improve application performance.

Reference link:

• [Java 11 official documentation](https://docs.oracle.com/en/java/javase/11/docs/api/java.net .http/java/net/http/package-summary.html)

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