WebClient, HttpClient, OkHttp: 三个Java HTTP客户端的比较

这三个Java HTTP客户端库都可以用来发送HTTP请求并处理响应。以下是各自的简单比较和示例代码：

1. WebClient (Java 11及以上):

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
 
public class WebClientExample {
    public static void main(String[] args) throws Exception {
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create("http://example.com"))
                .build();
 
        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
        System.out.println(response.statusCode());
        System.out.println(response.body());
    }
}

2. HttpClient (Apache HttpComponents):

import org.apache.hc.client5.httpclient.HttpClientBuilder;
import org.apache.hc.core5.http.HttpEntity;
import org.apache.hc.core5.http.io.entity.EntityUtils;
import org.apache.hc.core5.http.HttpHost;
import org.apache.hc.core5.http.HttpResponse;
 
public class HttpClientExample {
    public static void main(String[] args) throws Exception {
        HttpClientBuilder builder = HttpClientBuilder.create();
        CloseableHttpClient client = builder.build();
 
        HttpGet request = new HttpGet("http://example.com");
        HttpResponse response = client.execute(request);
        HttpEntity entity = response.getEntity();
 
        System.out.println(response.getStatusLine().getStatusCode());
        System.out.println(EntityUtils.toString(entity));
    }
}

3. OkHttp (Square):

import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
 
public class OkHttpExample {
    public static void main(String[] args) throws Exception {
        OkHttpClient client = new OkHttpClient();
 
        Request request = new Request.Builder()
                .url("http://example.com")
                .build();
 
        Response response = client.newCall(request).execute();
        System.out.println(response.code());
        System.out.println(response.body().string());
    }
}

这些示例都是同步执行的，如果需要异步执行，可以使用各自库提供的异步API。