AJAX和PHP:如何阻止脚本被缓存?

时间:2014-11-25 20:11:59

标签: javascript php jquery ajax token

问题:

如何添加令牌?我的show_aht.php正在被缓存。我必须手动刷新我的show_aht.php,以便在我使用aht_button进行AJAX调用时在map.php中获取新数据。它非常令人沮丧。

当点击aht_button时,它会返回数据,但是如果我刷新页面和/或我重新点击按钮,它仍会显示旧数据或根本不执行任何操作。我必须手动刷新我的" show_aht.php"在我的浏览器上然后点击" aht_button"所以我可以显示从" show_aht.php"中检索到的新数据。

我不想发布我的PHP代码,因为它有很多东西..也许有人可以找到问题因为我没有线索。不确定我们是否可以自己重新加载PHP脚本?我只放了重要的东西。

提前感谢!

map.php JS:

<div id="aht">
    <button id="aht_button">AHT</button>    
</div>

<script type="text/javascript">
        $(document).ready(function() {
                $('#aht').click(function(){
                    $.ajax({
                    type:"GET",
                    url : "show_aht.php", //use a token here??
                    data:{ } ,
                    dataType: 'json',
                    success : function(data){
                        //get the MIN value from the array
                            var min = data.reduce(function(prev, curr) {
                                return isNaN(+curr['aht_value']) || prev < +curr['aht_value'] ? prev : +curr['aht_value'];
                            }, 1000000);

                            alert("min:" + min); 
                            //get the MAX value from the array
                            var max = data.reduce(function(prev, curr) {
                              return isNaN(+curr['aht_value']) || prev > +curr['aht_value'] ? prev : +curr['aht_value'];
                            }, -1000000); 

                            alert("max:" + max);
                            //function for calculation of background color depending on aht_value               
                            function conv(x){
                                return Math.floor((x - min) / (max - min) * 255);
                            }

                            //function for background color, if NA then show white background, either show from green to red
                            function colorMe(v){
                              return v == 'NA' ? "#FFF" : "rgb(" + conv(v) + "," + (255-conv(v)) + ",0)";
                            }

                        //going through all DIVs only once with this loop
                        for(var i = 0; i < data.length; i++) { // loop over results
                        var divForResult = $('#desk_' + data[i]['station']); // look for div for this object
                        if(divForResult.length) { // if a div was found
                            divForResult.html(data[i]['aht_value']).css("background-color", colorMe(data[i]['aht_value']));
                        }//end if
                        }//end for  
                    }//end success
                });//end ajax   
              });//end click
            });//end rdy
        </script>

show_aht.php:

include 'db_conn_retca2003.php';
include 'db_conn_retca2001.php';
header('Content-type: application/json');

    /****************************************************
    matching USER array and MEMO array 
    for matching username values
    /****************************************************/
    $result = array();
    foreach ($memo as $username => $memodata) {
    if (in_array($username, array_keys($user))) {
    // Match username against the keys of $user (the usernames) 
    $userdata = $user[$username];
    //if AHT is null give N/A as value
    if (is_null($memodata['aht_value'])) {
        $result[] = array( 'username'  => $userdata['username'],
                                             'aht_value' => 'NA',
                                             'station'  => $userdata['station']
                                            );
    }//end inner if 
    //else give the actual value of AHT without the decimals
    else {
        $result[] = array( 'username'  => $userdata['username'],
                                             'aht_value' => substr($memodata['aht_value'],0,-3),
                                             'station'   => $userdata['station']
                                        );
    }//end else
    }//end outer if
    }//end for
  echo json_encode($result);
?>

1 个答案:

答案 0 :(得分:3)

您可以通过多种方式停止浏览器缓存。一种是发送不表示缓存的标头。来自How to control web page caching, across all browsers?

  

适用于所有提及的正确的最小标头集   浏览器:

Cache-Control: no-cache, no-store, must-revalidate Pragma: no-cache Expires: 0 
     

使用PHP:

header('Cache-Control: no-cache, no-store, must-revalidate'); // HTTP 1.1. 
header('Pragma: no-cache'); // HTTP 1.0. header('Expires: 0'); // Proxies.
     

使用HTML:

<meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate" /> 
<meta http-equiv="Pragma" content="no-cache" />
<meta http-equiv="Expires" content="0" />

请注意,此方法取决于遵循无缓存标头的浏览器。这不是保证。

您还可以在链接到不希望缓存的文件时添加包含当前时间戳的查询字符串变量。由于您每次都要访问不同的网址,因此浏览器不会缓存。