如果你在WordPress中这样做，那么有一个简单的解决方案:

add_action( 'parse_request', function ($wp) {
    $data = /* Your data to serialise. */
    wp_send_json_success($data); /* Returns the data with a success flag. */
    exit(); /* Prevents more response from the server. */
})

请注意，这不在wp_head钩子中，该钩子将始终返回大部分头部，即使您立即退出。parse_request在序列中出现得更早。

如果你需要从发送自定义信息的php中获取json，你可以添加这个头('Content-Type: application/json');在打印任何其他东西之前，所以然后你可以打印你的自定义echo '{"monto": "'.$monto[0]->valor.'"，"moneda":"'.$moneda[0]->nombre.'"，"simbolo":"'.$moneda[0]->simbolo.'"}';

<?php
$data = /** whatever you're serializing **/;
header("Content-type: application/json; charset=utf-8");
echo json_encode($data);
?>

尝试json_encode对数据进行编码，并设置带有header的content-type (' content-type: application/json');

如上所述:

header('Content-Type: application/json');

会完成这项工作。但请记住:

即使没有使用这个报头，Ajax读取json也没有问题，除非您的json包含一些HTML标记。在这种情况下，您需要将头文件设置为application/json。 确保您的文件不是用UTF8-BOM编码的。这种格式在文件顶部添加了一个字符，因此header()调用将失败。

无论何时你试图为API返回JSON响应，或者确保你有适当的标题，也确保你返回一个有效的JSON数据。

下面是示例脚本，它可以帮助您从PHP数组或返回JSON响应 来自JSON文件。

PHP脚本(代码):

<?php

// Set required headers
header('Content-Type: application/json; charset=utf-8');
header('Access-Control-Allow-Origin: *');

/**
 * Example: First
 *
 * Get JSON data from JSON file and retun as JSON response
 */

// Get JSON data from JSON file
$json = file_get_contents('response.json');

// Output, response
echo $json;

/** =. =.=. =.=. =.=. =.=. =.=. =.=. =.=. =.=. =.=. =.  */

/**
 * Example: Second
 *
 * Build JSON data from PHP array and retun as JSON response
 */

// Or build JSON data from array (PHP)
$json_var = [
  'hashtag' => 'HealthMatters',
  'id' => '072b3d65-9168-49fd-a1c1-a4700fc017e0',
  'sentiment' => [
    'negative' => 44,
    'positive' => 56,
  ],
  'total' => '3400',
  'users' => [
    [
      'profile_image_url' => 'http://a2.twimg.com/profile_images/1285770264/PGP_normal.jpg',
      'screen_name' => 'rayalrumbel',
      'text' => 'Tweet (A), #HealthMatters because life is cool :) We love this life and want to spend more.',
      'timestamp' => '{{$timestamp}}',
    ],
    [
      'profile_image_url' => 'http://a2.twimg.com/profile_images/1285770264/PGP_normal.jpg',
      'screen_name' => 'mikedingdong',
      'text' => 'Tweet (B), #HealthMatters because life is cool :) We love this life and want to spend more.',
      'timestamp' => '{{$timestamp}}',
    ],
    [
      'profile_image_url' => 'http://a2.twimg.com/profile_images/1285770264/PGP_normal.jpg',
      'screen_name' => 'ScottMili',
      'text' => 'Tweet (C), #HealthMatters because life is cool :) We love this life and want to spend more.',
      'timestamp' => '{{$timestamp}}',
    ],
    [
      'profile_image_url' => 'http://a2.twimg.com/profile_images/1285770264/PGP_normal.jpg',
      'screen_name' => 'yogibawa',
      'text' => 'Tweet (D), #HealthMatters because life is cool :) We love this life and want to spend more.',
      'timestamp' => '{{$timestamp}}',
    ],
  ],
];

// Output, response
echo json_encode($json_var);

JSON文件(JSON数据):

{
    "hashtag": "HealthMatters", 
    "id": "072b3d65-9168-49fd-a1c1-a4700fc017e0", 
    "sentiment": {
        "negative": 44, 
        "positive": 56
    }, 
    "total": "3400", 
    "users": [
        {
            "profile_image_url": "http://a2.twimg.com/profile_images/1285770264/PGP_normal.jpg", 
            "screen_name": "rayalrumbel", 
            "text": "Tweet (A), #HealthMatters because life is cool :) We love this life and want to spend more.", 
            "timestamp": "{{$timestamp}}"
        }, 
        {
            "profile_image_url": "http://a2.twimg.com/profile_images/1285770264/PGP_normal.jpg", 
            "screen_name": "mikedingdong", 
            "text": "Tweet (B), #HealthMatters because life is cool :) We love this life and want to spend more.", 
            "timestamp": "{{$timestamp}}"
        }, 
        {
            "profile_image_url": "http://a2.twimg.com/profile_images/1285770264/PGP_normal.jpg", 
            "screen_name": "ScottMili", 
            "text": "Tweet (C), #HealthMatters because life is cool :) We love this life and want to spend more.", 
            "timestamp": "{{$timestamp}}"
        }, 
        {
            "profile_image_url": "http://a2.twimg.com/profile_images/1285770264/PGP_normal.jpg", 
            "screen_name": "yogibawa", 
            "text": "Tweet (D), #HealthMatters because life is cool :) We love this life and want to spend more.", 
            "timestamp": "{{$timestamp}}"
        }
    ]
}

JSON Screeshot: