如何用Java的HttpPost发送空二进制数据？

你需要实现的curl命令为：

curl $CURL_OPTS -X POST --data-binary {} -s -K <(cat <<< "-u micromdm:$API_TOKEN") "$SERVER_URL/$endpoint"

这个命令核心是发送内容为{}的二进制数据，同时携带Basic认证信息。下面是可行的Java代码示例（基于Apache HttpClient）：

对应curl行为的完整代码 #

import org.apache.http.HttpResponse;
import org.apache.http.auth.UsernamePasswordCredentials;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ByteArrayEntity;
import org.apache.http.impl.auth.BasicScheme;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

public class PostBinaryDataExample {
    public static void main(String[] args) {
        // 替换为你的实际配置
        String serverUrl = "https://your-server.com";
        String endpoint = "your/endpoint/path";
        String apiToken = "your-api-token-here";
        
        String fullUrl = serverUrl + "/" + endpoint;

        try (CloseableHttpClient httpClient = HttpClients.createDefault()) {
            HttpPost httpPost = new HttpPost(fullUrl);

            // 设置请求头
            httpPost.addHeader("Accept", "application/json;charset=utf-8");
            httpPost.addHeader("Content-Type", "application/json;charset=utf-8");

            // 处理Basic认证（对应curl的-u参数）
            UsernamePasswordCredentials credentials = new UsernamePasswordCredentials("micromdm", apiToken);
            httpPost.addHeader(new BasicScheme().authenticate(credentials, httpPost, null));

            // 对应--data-binary {}，发送JSON空对象的二进制数据
            byte[] binaryContent = "{}".getBytes("UTF-8");
            ByteArrayEntity entity = new ByteArrayEntity(binaryContent);
            httpPost.setEntity(entity);

            // 执行请求
            HttpResponse response = httpClient.execute(httpPost);

            // 可添加响应处理逻辑，比如打印状态码
            System.out.println("响应状态码：" + response.getStatusLine().getStatusCode());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

关键点说明 #

1. Basic认证处理：curl的-u参数对应HTTP Basic认证，代码中用BasicScheme自动生成认证头，比手动拼接Authorization头更规范。
2. 二进制数据内容：--data-binary {}实际发送的是UTF-8编码的{}字节数组，并非完全空的二进制数据。如果需要发送完全无内容的请求（对应curl --data-binary ''），可以替换Entity部分：

   // 发送空二进制数据（Content-Length为0）
   ByteArrayEntity emptyEntity = new ByteArrayEntity(new byte[0]);
   httpPost.setEntity(emptyEntity, org.apache.http.entity.ContentType.DEFAULT_BINARY);
   

3. 依赖提示：确保你的项目中引入了Apache HttpClient的依赖，比如Maven：

   <dependency>
       <groupId>org.apache.httpcomponents</groupId>
       <artifactId>httpclient</artifactId>
       <version>4.5.14</version>
   </dependency>
   

内容的提问来源于stack exchange，提问作者Nick Dong