用header(' content -type: application/json')设置内容类型;然后对数据进行回显。

是的，你需要使用echo来显示输出。Mimetype: application / json

用header(' content -type: application/json')设置内容类型;然后对数据进行回显。

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:

根据json_encode的手册，该方法可以返回一个非字符串(false):

成功时返回JSON编码字符串，失败时返回FALSE。

当这种情况发生时，echo json_encode($data)将输出空字符串，这是无效的JSON。

如果json_encode的参数包含一个非UTF-8字符串，则json_encode将失败(并返回false)。

这个错误情况应该在PHP中捕获，例如:

<?php
header("Content-Type: application/json");

// Collect what you need in the $data variable.

$json = json_encode($data);
if ($json === false) {
    // Avoid echo of empty string (which is invalid JSON), and
    // JSONify the error message instead:
    $json = json_encode(["jsonError" => json_last_error_msg()]);
    if ($json === false) {
        // This should not happen, but we go all the way now:
        $json = '{"jsonError":"unknown"}';
    }
    // Set HTTP response status code to: 500 - Internal Server Error
    http_response_code(500);
}
echo $json;
?>

然后，接收端当然应该知道jsonError属性的存在表明了一个错误条件，它应该相应地处理这个错误条件。

在生产模式下，最好只向客户端发送一般的错误状态，并记录更具体的错误消息，以便以后进行调查。

在PHP文档中阅读更多关于处理JSON错误的内容。

设置访问安全性也很好——只需将*替换为您希望能够访问它的域。

<?php
header('Access-Control-Allow-Origin: *');
header('Content-type: application/json');
    $response = array();
    $response[0] = array(
        'id' => '1',
        'value1'=> 'value1',
        'value2'=> 'value2'
    );

echo json_encode($response); 
?>

这里有更多的例子:如何绕过Access-Control-Allow-Origin?