Apache HttpClient を使用して Java で JSON ペイロードを含む HTTP POST リクエストを実行する方法

// Create an HttpClient
HttpClient httpClient = HttpClientBuilder.create().build();
try {
    // Create an HttpPost request
    HttpPost request = new HttpPost("http://yoururl");
    // Create a StringEntity with the JSON payload
    StringEntity params = new StringEntity("details={\"" + "name" + "\":\"" + "John" + "\",\"" + "age" + "\":\"" + 20 + "\"}");
    // Set the content type
    request.addHeader("content-type", "application/x-www-form-urlencoded");
    // Set the StringEntity as the request body
    request.setEntity(params);
    // Execute the request
    HttpResponse response = httpClient.execute(request);
} catch (Exception ex) {
} finally {
    // Clean up the HttpClient
    httpClient.getConnectionManager().shutdown();
}