/**
 * @author      default7<default7@zbphp.com>
 * @description 演示PHP弹出下载的原理
 *
 * @param $file_name
 */
function downFile($file_name)
{
    $file_path = "/tmp/" . $file_name;
    $buffer = 102400; //一次返回102400个字节
    if (!file_exists($file_path)) {
        echo "<script type='text/javascript'> alert('对不起！该文件不存在或已被删除。'); </script>";

        return;
    }
    $fp = fopen($file_path, "r");
    $file_size = filesize($file_path);
    $file_data = http://www.mamicode.com/'';>