Output loading message in php

问题

Problem:

Before I perform a very long computational process, I would like to output a loading message to the user.

Code:

<html>        
<!doctype html>
            <head>
                <title>Loading</title>
            </head>

    <?php

    function longProcess()
    {
       //where long process takes a long time to compute
    }

    ?>
            <body>
                <?php
                        echo <div id = 'loading'> LOADING </div>
                        echo '</body>';
                        echo '</html>';
                        flush();
                        longProcess();

                ?>

Further Details:

Basically, before I call the longProcess function, I wish to output LOADING to the user. I use the flush so I can output the closing tags of HTML, and then call the longProcess function. The problem is that it is not being output and the server is computing the long process.

回答1:

What you need is probably a comet-like feature. Try the following to make it work.

<?php
// Disable buffering
@apache_setenv('no-gzip', 1);
@ini_set('zlib.output_compression', 0);
@ini_set('output_buffering', 'Off');
@ini_set('implicit_flush', 1);
// Flush buffers
ob_implicit_flush(1);
for ($i = 0, $level = ob_get_level(); $i < $level; $i++) ob_end_flush();
?><!DOCTYPE html>
<html>
<head>
  <title>Loading</title>
</head>
<body>
  <div id="loading">LOADING</div>
<?php
// We need to send enough junk messages to make it works for all browsers
echo str_repeat(" ", 1024), "\n";

ob_start();
// Long process starts here
// For this example, just sleep for 5 seconds
sleep(5); 
echo "Loaded";
// Flush output like this
ob_flush();
flush();
?>
</body>
</html>

References:

http://jsjoy.com/blog/197/simple-php-comet-example
Why doesn't this PHP code (comet) work?
http://php.net/manual/en/function.flush.php#109239

回答2:

PHP is server-side. You can't output a loading message.

You can try to make a page (place your "loading" message in this page) that redirects automaticly to your target page. Now you see the loading-page until your target-page is loaded

回答3:

You could possibly output JavaScript using the PHP. You would perform the following:

Before longProcess(), output JavaScript to set a #contents DIV within <body> to be a loading animation
Run longProcess()
Output JavaScript to set the #contents DIV within <body> to output whatever you want, be it data, "finished" or whatever.

Just a quick idea, and almost certainly not the nicest, but it'll work.

An alternative is to re-direct using PHP to a finished page, once the loading process has finished using header.

header('Location: http://www.example.com/');

Finally, Xiao's disable buffering is something you should take a look at!

回答4:

Instead of computing in the same page,

load the page with loading symbol
Initiate the on load ajax call to your PHP file and do all your computation
On response of the ajax call make your output replacing your div of loading.

来源：https://stackoverflow.com/questions/14120084/output-loading-message-in-php

标签

php