一，原始方式

使用java.net包中的HttpURLConnection类。以下是一个简单的示例代码，用于发送GET请求并获取响应：

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import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpGetRequestExample {
    public static void main(String[] args) {
        try {
            // 创建URL对象
            URL url = new URL("http://example.com");

            // 打开连接
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();

            // 设置请求方法
            connection.setRequestMethod("GET");

            // 获取响应代码
            int responseCode = connection.getResponseCode();
            System.out.println("Response Code: " + responseCode);

            // 读取响应内容
            BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String line;
            StringBuilder response = new StringBuilder();
            while ((line = reader.readLine()) != null) {
                response.append(line);
            }
            reader.close();

            // 打印响应内容
            System.out.println("Response: " + response.toString());

            // 断开连接
            connection.disconnect();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

上述示例代码用于发送GET请求，您可以更改请求方法和URL以适应您的实际需求。请注意，HTTP请求是不安全的，建议在实际使用中使用HTTPS来确保数据的安全传输。

二，使用Apache HttpClient库

使用Apache HttpClient库。请确保您的项目中包含了相关的依赖

示例代码：

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import java.io.BufferedReader;
import java.io.InputStreamReader;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

public class HttpsPostRequestExample {
    public static void main(String[] args) {
        try {
            // 创建HttpClient对象
            HttpClient httpClient = HttpClients.createDefault();

            // 创建HttpPost对象，并设置URL
            HttpPost httpPost = new HttpPost("https://example.com");

            // 设置请求头
            httpPost.setHeader("Content-Type", "application/json");

            // 设置请求体
            String requestBody = "{"key1":"value1","key2":"value2"}";
            StringEntity requestEntity = new StringEntity(requestBody);
            httpPost.setEntity(requestEntity);

            // 发送POST请求
            HttpResponse response = httpClient.execute(httpPost);

            // 获取响应代码
            int responseCode = response.getStatusLine().getStatusCode();
            System.out.println("Response Code: " + responseCode);

            // 读取响应内容
            BufferedReader reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
            StringBuilder responseContent = new StringBuilder();
            String line;
            while ((line = reader.readLine()) != null) {
                responseContent.append(line);
            }
            reader.close();

            // 打印响应内容
            System.out.println("Response: " + responseContent.toString());

            // 断开连接
            httpClient.getConnectionManager().shutdown();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

上述示例代码中，我们使用了Apache HttpClient库来发送HTTPS的POST请求。您可以根据实际需求修改请求的URL、请求头、请求体等部分。请确保您的项目中包含了Apache HttpClient库的依赖。