在Java中實現Nginx轉發功能可以借助第三方庫，比如Apache HttpComponents或OkHttp來發送HTTP請求。以下是一個簡單的示例代碼：

import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

public class NginxForwardingExample {

    public static void main(String[] args) {
        String nginxUrl = "http://nginx-server.com/api/resource";
        
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpGet httpGetRequest = new HttpGet(nginxUrl);
        
        try {
            HttpResponse response = httpClient.execute(httpGetRequest);
            
            // 處理響應內容
            System.out.println("Response Code: " + response.getStatusLine().getStatusCode());
            // 其他處理邏輯
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                httpClient.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}

以上代碼通過創建一個HTTP客戶端并發送GET請求到Nginx服務器，然后處理響應內容。您可以根據需要修改請求方法、請求頭、請求體等內容來實現更復雜的轉發功能。