使用WordPress Transient API保存网页

Question

I'm struggling to create web page caches with the Transient API. When I try to save the whole source code, something goes wrong. I'm suspecting that WordPress internally correct the format. In that case, is there a good way to save data intact?

The below code is ready to run as a plugin and demonstrates the problem. When the cache is not created, it shows a web page but once it is created and tries to show the cached data, a blank page is displayed.

<?php
/* Plugin Name: Sample Transient */

add_action('admin_menu', 'sample_transient_menu');
function sample_transient_menu() {
    add_options_page(
        'Sample Transient', 
        'Sample Transient', 
        'manage_options',
        'sample_transient', 
        'sample_transient_admin');
}
function sample_transient_admin() {
    ?>
    <div class="wrap">
    <?php

        $strTransient = 'sample_transient_html';
        $html = get_transient($strTransient);       
        if( false === $html ) {
            echo 'cache is not used: ' . $strTransient . '<br />';      
            $html = wp_remote_get('http://www.google.com'); 
            $html = $html['body'];
            // $html = '<div>hello world</div>'; // <-- this works fine
            set_transient($strTransient, htmlspecialchars($html), 60 );

            $tmp = get_transient($strTransient);
            if (false === $tmp)
                echo 'transient is not saved.';
            else
                echo 'transient is now saved: ' . $strTransient;    
        } else 
            echo 'cache is used. <br />';
        print_r(htmlspecialchars_decode($html));
    ?>
    </div>
    <?php
}

[Edit] Also, it would be appreciated if somebody can provide a solution for the encoding problem. Currently it just shows broken characters.

Answer 1

Encrypting the strings just worked. I'm not sure about the speed though.

<?php
/* Plugin Name: Sample Transient */

add_action('admin_menu', 'sample_transient_menu');
function sample_transient_menu() {
    add_options_page(
        'Sample Transient', 
        'Sample Transient', 
        'manage_options',
        'sample_transient', 
        'sample_transient_admin');
}
function sample_transient_admin() {
    ?>
    <div class="wrap">
    <?php

        $strTransient = 'sample_transient_html3';
        $key = 'sample_transient';
        $html = get_transient($strTransient);   
        if( false === $html ) {
            echo 'cache is not used: ' . $strTransient . '<br />';      
            $html = wp_remote_get('http://www.google.com'); 
            $html = $html['body'];  
            $savehtml = base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_256, md5($key), $html, MCRYPT_MODE_CBC, md5(md5($key))));
            set_transient($strTransient, $savehtml, 60 );
        } else {
            echo 'cache is used. <br />';
            $html = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, md5($key), base64_decode($html), MCRYPT_MODE_CBC, md5(md5($key)));  
        }
        print_r($html);
    ?>
    </div>
    <?php
}

Reference: Best way to use PHP to encrypt and decrypt passwords?