Java 发送 POST 请求并传递 JSON 参数 - 使用 Apache HttpClient

在 Java 中，可以使用不同的库来发送 POST 请求并传递 JSON 参数。以下是使用常见的 Apache HttpClient 库的示例代码：

import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

public class Main {
    public static void main(String[] args) {
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpPost httpPost = new HttpPost("http://example.com/api/endpoint");

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

        // 设置 JSON 参数
        String json = '{"name": "John", "age": 30}';
        StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);
        httpPost.setEntity(entity);

        try {
            CloseableHttpResponse response = httpClient.execute(httpPost);
            HttpEntity responseEntity = response.getEntity();

            // 处理响应
            if (responseEntity != null) {
                String responseBody = EntityUtils.toString(responseEntity);
                System.out.println(responseBody);
            }

            response.close();
            httpClient.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

以上代码将发送一个 POST 请求到 http://example.com/api/endpoint，并传递 JSON 参数 '{"name": "John", "age": 30}'。你可以根据实际情况修改 URL、请求头和 JSON 参数。