Jdk11新增HttpClient客户端，发送get请求

• JDK11新增HttpClient，⽀持 HTT/1.1, HTTP/2

• 常⽤类和接⼝讲解

HttpClient.Builder
HttpClient 构建⼯具类

HttpRequest.Builder
HttpRequest 构建⼯具类

HttpRequest.BodyPublisher
将java 对象转换为可发送的HTTP request body字节流, 如form表单提交

HttpResponse.BodyHandler
处理接收到的 Response Body

• 发送get请求案例

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 Main {
    
    public static void main(String[] args) throws Exception {
        testGet();
    }
    
    private static final String targetUrl = "http://api.xdclass.net/pub/api/v1/web/all_category";

    private static final URI uri = URI.create(targetUrl);

    private static final void testGet() {
        //var httpClient = HttpClient.newHttpClient();      // 方式1
        
        //设置建立连接的超时 connect timeout
        var httpClient = HttpClient.newBuilder().connectTimeout(Duration.ofMillis(5000)).build();   // 方式2

        var request = HttpRequest.newBuilder().timeout(Duration.ofMillis(3000))
                .header("key1", "v1")
                .header("key2", "v2")
                .uri(uri).build();
        try {
            var response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());
            System.out.println(response.body());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
}