在android中Post方法返回400个错误请求

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpPost;
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 HttpPostExample {
    public static void main(String[] args) {
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpPost httpPost = new HttpPost("https://example.com/api/resource");

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

            // 创建JSON对象并设置为请求体
            String json = "{\"key\":\"value\"}";
            StringEntity entity = new StringEntity(json, "UTF-8");
            httpPost.setEntity(entity);

            // 发送请求并获取响应
            HttpResponse response = httpClient.execute(httpPost);
            int statusCode = response.getStatusLine().getStatusCode();
            HttpEntity responseEntity = response.getEntity();

            if (responseEntity != null) {
                String responseString = EntityUtils.toString(responseEntity);
                System.out.println("Response: " + responseString);
            }

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