沉冰浮水

/**
 * Extract or set image
 *
 * @param object $article
 * @param string $type   Used to determine the return format
 * @return string imgurl | <img />
 */
function demoAPP_Thumbnail($article, $type = 'imgurl')
{

  $matches = null;
  preg_match_all("/<img[^>]*src=\"([^\"]+)\"[^>]*>/i", $article->Content, $matches);
  if (isset($matches[1]) && count($matches[1]) > 0) {
    $imgurl = $matches[1][0];
  } else {
    $imgurl = demoAPP_setRndImg($article->ID);
    // $imgurl = demoAPP_setRndImgNetwork(); // This method is not scientific under current requirements. It may be restricted by the service provider.
  }
  // Default return image address
  if ($type == 'imgurl') {
    return $imgurl;
  }
  // Passing any other value returns <img /> tag
  $tplImg = '<img src="imgurl" alt="title">';
  return strtr($tplImg, array('imgurl' => $imgurl, 'title' => $article->Title));
}

/**
 * Directly callable random image interface
 *
 * @param string $rndhash Pass a parameter to prevent image duplication
 * @return string
 */
function demoAPP_setRndImg($rndhash)
{
  return "https://picsum.photos/350/260?random={$rndhash}";
}

/**
 * The interface itself returns json, requires additional extraction of image address
 *
 * @return string
 */
function demoAPP_setRndImgNetwork()
{
  global $zbp;
  // Default image when failed
  $imgurl = "{$zbp->host}zb_users/theme/demoAPP/var/images/no-image.jpg";
  // Interface address
  $url = "https://api.vvhan.com/api/acgimg?type=json";
  $http = Network::Create();
  $http->open('GET', $url);
  // $http->setTimeOuts(10, 10, 0, 0);
  $http->send();
  // Parse the fetched content
  if ($http->status == 200 && $json = json_decode($http->responseText, true)) {
    // Return fields are subject to the actual interface
    $imgurl = $json['imgurl'];
  }
  return $imgurl;
}

<a href="{$article.Url}" title="{$article.Title}">
{demoAPP_Thumbnail($article,1)}
</a>