两种可能性：使用the_content-筛选，或者在模板中调用它。

您可以将插件扔到文件夹中，或在主题函数中添加一个（或两个）函数。php文件。过滤器仅针对post格式触发link, 而模板标记可以在循环中更通用地使用。

作为插件

<?php
! defined( \'ABSPATH\' ) AND exit;
/* Plugin Name: (#16365) »kaiser« Get 1st link inside the content */

// As an public API function
function wpse16365_get_content_link( $content = false, $echo = false )
{
if ( ! in_the_loop() )
    return;

    // allows using this function also for excerpts
    ! $content AND $content = get_the_content();

    $content = preg_match_all( \'/href\\s*=\\s*[\\"\\\']([^\\"\\\']+)/\', $content, $links );
    $content = $links[1][0];
    $content = make_clickable( $content );

    // if you set the 2nd arg to true, you\'ll echo the output, else just return for later usage
    $echo AND print $content;

    return $content;
}

// As a the_content-filter Callback
function wpse16365_get_content_link_cb( $content )
{
    if ( \'link\' !== get_post_format() )
        return $content;

    $content = preg_match_all( \'/href\\s*=\\s*[\\"\\\']([^\\"\\\']+)/\', $content, $links );
    $content = $links[1][0];

    return make_clickable( $content );
}
add_filter( \'the_content\', \'wpse16365_get_content_link_cb\' );

更为更新和干净的方法：

function get_link_url() {
    $content = get_the_content();
    $has_url = get_url_in_content( $content );

    return ( $has_url ) ? $has_url : apply_filters( \'the_permalink\', get_permalink() );
}

http://www.wprecipes.com/how-to-get-the-first-image-from-the-post-and-display-it

http://bavotasan.com/tutorials/retrieve-the-first-image-from-a-wordpress-post/

http://wordpress.org/extend/plugins/simple-image-grabber/