HttpClient最丰富和灵活的版本

// Java 8 and earlier
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;

public class Main {
    public static void main(String[] args) throws IOException {
        URL url = new URL("https://www.example.com");
        HttpURLConnection con = (HttpURLConnection) url.openConnection();
        con.setRequestMethod("GET");
        int status = con.getResponseCode();
        System.out.println(status);
    }
}
// 优点：简单易用。缺点：功能有限，不够灵活。

// Java 8
import java.io.IOException;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

public class Main {
    public static void main(String[] args) throws IOException, InterruptedException {
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create("https://www.example.com"))
                .build();
        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
        System.out.println(response.statusCode());
    }
}
// 优点：比Java 8和之前的版本具有更多的功能和灵活性。缺点：仍然缺少一些高级功能。

// Java 9
import java.io.IOException;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

public class Main {
    public static void main(String[] args) throws IOException, InterruptedException {
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create("https://www.example.com"))
                .GET()
                .build();
        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
        System.out.println(response.statusCode());
    }
}
// 优点：添加了Java 8中缺少的一些功能。缺点：仍然不如Java 11功能丰富。

// Java 11
import java.io.IOException;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

public class Main {
    public static void main(String[] args) throws IOException, InterruptedException {
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create("https://www.example.com"))
                .GET()
                .build();
        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
        System.out.println(response.statusCode());
    }
}
// 优点：HttpClient最丰富和灵活的版本。缺点：需要Java 11或更高版本。