import java.net.URI;  
import java.net.http.HttpClient;  
import java.net.http.HttpRequest;  
import java.net.http.HttpResponse;  
import java.net.http.HttpTimeoutException;  
  
public class JdkHttpClientTest {  

    public static void main(String[] args) {  
	
        HttpClient client = HttpClient.newHttpClient();  
		
        HttpRequest request = HttpRequest.newBuilder()  
                .uri(URI.create("https://123.com"))  
                .build();  
  
        try {  
		
            HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());  
			
            System.out.println(response.statusCode()); 
			
            System.out.println(response.body());  
			
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
		
    }  
}

public class ApacheHttpClientTest {  

    public static void main(String[] args) {  
	
		HttpGet request = new HttpGet("https://1234.com");
		CloseableHttpClient client = HttpClients.custom().build(); 
  
        try {  
		
            HttpClientResponseHandler<String> responseHandler = new BasicHttpClientResponseHandler(); 
			
			String ret = client.execute(httpget, responseHandler) ;
			
			System.out.println(ret) ; 
			
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
		
    }  	 
    
}

public void OkHttpClientTest() {
	// 1. 創(chuàng)建一個(gè)OkHttpClient實(shí)例  
	OkHttpClient client = new OkHttpClient();

	// 2. 創(chuàng)建一個(gè)Request對(duì)象  
	Request request = new Request.Builder().url("http://1234.com") // 設(shè)置請(qǐng)求的URL  
			.build();

	// 3. 發(fā)送請(qǐng)求并獲取Response對(duì)象  
	try (Response response = client.newCall(request).execute()) {
		
		String responseBody = response.body().string();
		
		System.out.println(responseBody);
		
	} catch (IOException e) {
		e.printStackTrace();
	}
}

public class RestTemplateTest {  
    public static void main(String[] args) {  
        RestTemplate restTemplate = new RestTemplate();  
  
        String response = restTemplate.getForObject("https://1234.com", String.class);  
		
        System.out.println(response);  
    }  
}

public class WebClientExample {  
  
    public static void main(String[] args) {  
        WebClient webClient = WebClient.create("http://1234.com");  
  
        webClient.get()  
                .uri("/api/data")  
                .retrieve()  
                .bodyToMono(String.class)  
                .subscribe(  
                        body -> System.out.println(body),  
                        error -> System.err.println("Error occurred: " + error)  
                );  
    }  
}

<dependency>
  <groupId>io.github.openfeign</groupId>
  <artifactId>feign-core</artifactId>
  <version>13.2.1</version>
</dependency>

public interface MyFeignClient {  
  
    @RequestLine("GET /api/data")  
    String getData();  
  
    static MyFeignClient create() {  
        return Feign.builder()  
                .encoder(new JacksonEncoder())  
                .decoder(new JacksonDecoder())  
                .logger(new Logger.ErrorLogger())  
                .logLevel(Level.FULL)  
                .retryer(new Retryer.Default(100, TimeUnit.MILLISECONDS.toMillis(1), 5))  
                .target(Target.EmptyTarget.create(MyFeignClient.class, "http://123456.com"));  
    }  
}

MyFeignClient client = MyFeignClient.create();  
String data = client.getData();  
System.out.println(data);