您可以使用PHPstrip_tags 并连接到the_content 通过检查用户是否is logged in.

将此添加到functions.php 文件

add_filter( \'the_content\', \'wpse_remove_img\' );
function wpse_remove_img( $content ){

  if( ! is_user_logged_in() ){

    // You need to specify which tag you want to keep here it\'s p, a, h2,span, div.
    // Adjust accordingly (you might want to add other or remove all)
    $content = strip_tags($content, \'<p><a><h2><span><div>\'); 


  }

  return $content;

}

EDIT

如果要替换图像，我将使用PHPDOMDocument 执行搜索和替换。

请注意，对于某些HTML5标记，可能会遇到一些文本编码问题或警告。Hakre 深入解释为什么会发生这种情况，以及Gordon 很好地解释了这一点，都在StackExchange。

在下面的解决方案中，我通过在$content 已加载。以及临时禁用libxml错误，这样我们就不会因为使用libxml_use_internal_errors

再一次，这会进入你的functions.php

add_filter( \'the_content\', \'wpse_replace_img\' );
function wpse_replace_img( $content ){

  if( ! is_user_logged_in() ){

    $dom = new DOMDocument();

    libxml_use_internal_errors(true); // deactivating errors
    // Load without added HTML and doctype, see https://stackoverflow.com/a/22490902/4643867
    $dom->loadHTML( \'<?xml encoding="UTF-8">\' . $content, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD ); // adding encoding
    libxml_use_internal_errors(false); // reactivating errors

    $tags = $dom->getElementsByTagName( \'img\' );

    foreach ($tags as $img) {
      $new_src_url = \'http://url/to/your/filler-image.jpg\';
            $img->setAttribute( \'src\', $new_src_url );
            $img->setAttribute( \'srcset\', \'\' );

    }

    $content = $dom->saveHTML();

  }

  return $content;

}

EDIT

好的，这里有一个考虑到包装的编辑<a> 图像周围的标记。第一个解决方案将用#

add_filter( \'the_content\', \'wpse_replace_img\' );
function wpse_replace_img( $content ){

  if( ! is_user_logged_in() ){

    $dom = new DOMDocument();

    libxml_use_internal_errors(true);
    // Load without added HTML and doctype, see https://stackoverflow.com/a/22490902/4643867
    $dom->loadHTML( \'<?xml encoding="UTF-8">\' . $content, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD ); // adding encoding
    libxml_use_internal_errors(false);

    $tags  = $dom->getElementsByTagName( \'img\' );

    foreach ($tags as $img) {
      $new_src_url = \'http://url/to/your/filler-image.jpg\';
      $img->setAttribute( \'src\', $new_src_url );
      $img->setAttribute( \'srcset\', \'\' );

      if( $img->parentNode->tagName == \'a\' ){ // if the current image is wrapped by an <a> tag, replace href link with an #

        $img->parentNode->setAttribute( \'href\', \'#\' );

      }

    }

    $content = $dom->saveHTML();

  }

  return $content;

}

然后您还可以删除<a> 全部标记。在以下人员的帮助下matb33 在stackoverflow，我设法想出了这个解决方案。

add_filter( \'the_content\', \'wpse_replace_img\' );
function wpse_replace_img( $content ){

  if( ! is_user_logged_in() ){

    $dom = new DOMDocument();

    libxml_use_internal_errors(true);
    // Load without added HTML and doctype, see https://stackoverflow.com/a/22490902/4643867
    $dom->loadHTML( \'<?xml encoding="UTF-8">\' . $content, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD ); // adding encoding
    libxml_use_internal_errors(false);

    $tags  = $dom->getElementsByTagName( \'img\' );
    $fragment = $dom->createDocumentFragment();  // Create our new document fragment to manipulate


    foreach ($tags as $img) {
      $new_src_url = \'http://url/to/your/filler-image.jpg\';
      $img->setAttribute( \'src\', $new_src_url );
      $img->setAttribute( \'srcset\', \'\' );

      if( $img->parentNode->tagName == \'a\' ){ // if the current image has an  <a> tag as a parent apply replace our <a> tag with our <img> tag

        $a = $img->parentNode;
        $fragment->appendChild( $img->parentNode->childNodes->item( 0 ) ) ; // store our image node into the fragment
        $a->parentNode->replaceChild( $fragment, $a ); // replace our <a> tag with our <img> tag

      }

    }

    $content = $dom->saveHTML();

  }

  return $content;

}

EDIT

下面是如何仅适用于特定类别

add_filter( \'the_content\', \'wpse_replace_img\' );
function wpse_replace_img( $content ){

  if( ! is_user_logged_in() ){

    $apply_restriction = false;
    $categories = get_the_category();
    $restricted_cat = array(
        \'restricted_cat_slug\' // Our restricted category slug, since it\'s an array you could provide more than one
    );


    // Performing our check, switch the flag if we find a match
    foreach( $categories as $cat ){
        foreach( $restricted_cat as $r_cat ){
            if( $cat->slug == $r_cat ){
                $apply_restriction = true;
            }
        }
    }

    // Bail out without applying any restriction if no category match is found
    if( ! $apply_restriction ){
        return $content;
    }

    $dom = new DOMDocument();

    libxml_use_internal_errors(true);
    // Load without added HTML and doctype, see https://stackoverflow.com/a/22490902/4643867
    $dom->loadHTML( \'<?xml encoding="UTF-8">\' . $content, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD ); // adding encoding
    libxml_use_internal_errors(false);

    $tags  = $dom->getElementsByTagName( \'img\' );
    $fragment = $dom->createDocumentFragment();  // Create our new document fragment to manipulate


    foreach ($tags as $img) {
      $new_src_url = \'http://url/to/your/filler-image.jpg\';
      $img->setAttribute( \'src\', $new_src_url );
      $img->setAttribute( \'srcset\', \'\' );

      if( $img->parentNode->tagName == \'a\' ){ // if the current image has an  <a> tag as a parent apply replace our <a> tag with our <img> tag

        $a = $img->parentNode;
        $fragment->appendChild( $img->parentNode->childNodes->item( 0 ) ) ; // store our image node into the fragment
        $a->parentNode->replaceChild( $fragment, $a ); // replace our <a> tag with our <img> tag

      }

    }

    $content = $dom->saveHTML();

  }

  return $content;

}