我想创建一个downloadscript允许部队下载的JPG文件中。 这是我的PHP脚本：

i want to create a downloadscript which allows Force Download of JPGs. This is my php script:

<?php
    header("Pragma: public"); // required
    header("Expires: 0");
    header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
    header("Content-Description: File Transfer");
    header("Content-Type: image/jpg");
    header('Content-Disposition: attachment; filename="'.basename($GET['a']).'"');
    header("Content-Transfer-Encoding: binary");
    header("Content-Length: ".filesize(($GET['a']));
    readfile(($GET['a']);
?>

这是我的js code一code段：

This is a code segment of my js code:

function downloadFile(a){
    document.location = "download.php?a="+ a;
}

通过这个code样品没有任何反应。如果我追加的结果成HTML的标记时，它示出了该文件的内容。

With this code sample nothing happens. If i append the result into a HTML-tag, it shows the content of the file.

任何想法如何教浏览器下载这个文件？

Any ideas how to teach the browser to download this file?

编辑：SCRIPT更新

推荐答案

您无法下载文件，使用Ajax。所以，如果你有什么事情要发生在阿贾克斯，你应该回应返回URL，并将其应用于像 document.location =URL来开始下载过程。

You can't download files with ajax. So, if you have something that should happen on ajax, you should return url in response and apply it like document.location = "url"to start download process.

这里的一个音符。我记得，浏览器会阻止文件下载，如果它是由用户点击启动不。所以，这将正常工作：

One note here. As I remember, browser will block file download if it is initiated not by user click. So, this will work fine:

.click(function(){
   document.location = "download url"
})

但是，如果它是由用户点击启动不是，它将被阻止。因此，code是这样的：

But if it is started not by user click, it will be blocked. So, code like this:

.click(function(){
       $.ajax({...,
       success:function(download_url_from_server){
           document.location = download_url_from_server;
       }});           
    })

将由浏览器被阻塞。所以，如果你想通过一些数据后，您可以提交一个表单到隐藏的iframe或使用空白页＆LT;形式的目标=...：

 function checkToken(token){
    var $form = $("#downloadForm");
    if ($form.length == 0) {
        $form = $("<form>").attr({ "target": "_blank", "id": "downloadForm", "method": "POST", "action": "script.php" }).hide();
        $("body").append($form);
    }
    $form.find("input").remove();
    var args = { a: "checkToken", b: token }
    for (var field in args) {
        $form.append($("<input>").attr({"value":args[field], "name":field}));
    }
    $form.submit();
}

而在script.php的，你需要从的download.php立即执行code，如果令牌是好，还是做一个重定向到下载脚本：

And in script.php you need to execute code from download.php immediately, if token is Ok, or do a redirect to download script:

header("Location: download.php?a=" . $filename)