Force browser to ignore cache

2019-07-04 03:38发布

My code crops a photo. The cropped photo is constantly replaced but the browser only ever loads the first crop. I have scoured the web but nothing has worked. I have added random strings to the php - new.jpg?time=t - but this prevents the cropped image from saving. I have included

<head>   
    <meta charset="utf-8">   
    <meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate" />
    <meta http-equiv="Pragma" content="no-cache" />
    <meta http-equiv="Expires" content="-1" />
</head>

but the browser still loads from the cache. The HTML JavaScript and PHP follow. Any other suggestions?

                <html>
                <head>
                    <title>Image Crop</title>
                    <style>
                        body{
                            margin: 0;
                            padding: 0;
                        }
                        #container{
                            width: 300px;
                        }
                        #box{
                            position: absolute;
                            top: 0px;
                            left: 0px;
                            width: 100px;
                            height: 100px;
                            background: white;
                            border: 2px solid blue;
                            opacity: 0.5;
                        }
                        #crop_button{
                            background: #333;
                            color: #fff;
                            padding: 5px;
                            border: 0px;
                            margin: 5px;
                        }
                        #output{
                            position: absolute;
                            top: 0px;
                            left: 300px;
                        }
                    </style>
                </head>
                <body>
                    <div id="container">
                        <img src="resized_IMG0934.jpg"/>
                        <div id="box"></div>
                    </div>
                    <div id="output"><image />
                    </div>
                    <button id="crop_button">Crop</button>
                    <link rel="stylesheet" href="//code.jquery.com/ui/1.10.4/themes/smoothness/jquery-ui.css">
                    <script src="//code.jquery.com/jquery-1.10.2.js"></script>
                    <script src="//code.jquery.com/ui/1.10.4/jquery-ui.js"></script>
                    <script src="index.js"></script>
                </body>
            </html>

                 $(function() {
                $('#box').draggable({containment: '#container'});
                $('#box').resizable({containment: '#container'});
                $('#crop_button').click(function(){ 
                    var top = $('#box').position().top;
                    var left = $('#box').position().left;
                    var width = $('#box').width();
                    var height = $('#box').height();
                    $.post('crop.php', {top:top, left:left, width:width, height:height}, function(){
                        $('#output').html('<img src="new.jpg"/>');
                    });
                });
             });

                <?php
            $dst_x = 0;
            $dst_y = 0;
            $src_x = $_POST['left'];  //crop Start x
            $src_y = $_POST['top'];  //crop Start y
            $dst_w = $_POST['width']; //Thumb width
            $dst_h = $_POST['height']; //Thumb height
            $src_w = $_POST['width'];  //$src_w + $dst_w
            $src_h = $_POST['height'];  //$src_h + $dst_h

            $dst_image = imagecreatetruecolor($dst_w,$dst_h);
            $src_image = imagecreatefromjpeg("resized_IMG0934.jpg");
            imagecopyresampled($dst_image, $src_image, $dst_x, $dst_y, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h);
            imagejpeg($dst_image, "new.jpg");

3条回答
我欲成王,谁敢阻挡
2楼-- · 2019-07-04 04:32

You have the following choices: - add the following meta tag, this will force not to cache

<meta http-equiv="pragma" content="no-cache" /> which you have already as I see
  • moreover, if you want to load new version of the css file, do the following

< link rel="stylesheet" type="text/css" href="mystyle.css?version={NewVersionOnRequierd}">

  • same for the image
< img src="picture.jpg?123" alt="">
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手持菜刀,她持情操
3楼-- · 2019-07-04 04:33

Okay, I eventually solved the problem by appending a random string to the image element source, as I have tried many times. There appeared to be something wrong with my Firefox installation. Difficult to draw any conclusions. Thanks for the contributions.

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爷的心禁止访问
4楼-- · 2019-07-04 04:39

Create a hidden iframe and set its src as the image url as follows:

function refresh(url){
    var iframe = document.createElement('iframe')
    iframe.src = url
}
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