如果页面直接链接到javascript或php，重定向？

I need some javascript or php code to detect if user has linked directly to me site's page so I can then redirect it to the homepage.

Is this possible?

Check is the the host of your server is in the http_referer (it is the last url visited by the user).

function is_direct_link() {
    return (!empty($_SERVER['HTTP_REFERER']) && stripos($_SERVER['HTTP_REFERER'], $_SERVER['HTTP_HOST']) === false);
}

if (is_direct_link()) {
    header('location: http://www.google.com');
    exit();
}

If the referrer is empty, this will redirect to the home page:

<?php
if(!empty($_SERVER['HTTP_REFERER']) && stripos($_SERVER['HTTP_REFERER'], 'example.com') header("Location: example.com"); 
?>

Note that the referrer is not bulletproof by any stretch but it does the basic job.

<?php
  $referrer = $_SERVER['HTTP_REFERER'];

  // see if they are visiting from another website
  if (!empty($referrer) && stripos($referrer, 'mydomain.com') === false)
  {
    // redirect them to the main site
    header('Location: http://mydomain.com/');
    // stop php from going further
    exit;
  }

Something like that is (i think) what you're looking for.