使用 php 将文件上传到网站答案

【问题标题】：Upload a file to a website using php使用 php 将文件上传到网站
【发布时间】：2015-01-09 00:07:21
【问题描述】：

我是 php 新手，我正在尝试从这里修改代码：http://www.w3schools.com/php/php_file_upload.asp 文件上传后保持在同一页面上。

页面显示这些错误（文件上传前但文件上传后没有）：

Notice: Undefined index: fileToUpload in C:\xampp\htdocs\test-site\index.php on line 12
Sorry, file already exists.

Notice: Undefined index: fileToUpload in C:\xampp\htdocs\test-site\index.php on line 38
Sorry, only JPG, JPEG, PNG & GIF files are allowed.Sorry, your file was not uploaded.

文件上传正常。

这是代码：

<!DOCTYPE html>
<html>
<body>

<form action="<?php $_SERVER['PHP_SELF'] ?>" method="post" enctype="multipart/form-data">
    Select image to upload:
    <input type="file" name="fileToUpload" id="fileToUpload" class="upload_file">
    <input type="submit" value="Upload Image" name="submit">
</form>
<?php
$target_dir = "uploads/";
$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
$uploadOk = 1;
$imageFileType = pathinfo($target_file,PATHINFO_EXTENSION);
// Check if image file is a actual image or fake image
if(isset($_POST["submit"])) 
{
    $check = getimagesize($_FILES["fileToUpload"]["tmp_name"]);
    if($check !== false) 
    {
        echo "File is an image - " . $check["mime"] . ".";
        echo '<a href="'.$target_file.'">Download you file here</a>';
        $uploadOk = 1;
    } 
    else 
    {
        echo "File is not an image.";
        $uploadOk = 0;
    }
}
// Check if file already exists
if (file_exists($target_file)) 
{
    echo "Sorry, file already exists.";
    $uploadOk = 0;
}
// Check file size
if ($_FILES["fileToUpload"]["size"] > 500000) 
{
    echo "Sorry, your file is too large.";
    $uploadOk = 0;
}
// Allow certain file formats
if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg"&&         $imageFileType != "gif" ) 
{
    echo "Sorry, only JPG, JPEG, PNG & GIF files are allowed.";
    $uploadOk = 0;
}
// Check if $uploadOk is set to 0 by an error
if ($uploadOk == 0) 
{
    echo "Sorry, your file was not uploaded.";
// if everything is ok, try to upload file
} 
else 
{
    if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) 
    {
        echo "The file ". basename( $_FILES["fileToUpload"]["name"]). " has been uploaded.";
    } 
    else 
    {
        echo "Sorry, there was an error uploading your file.";
    }
}
?>
</body>
</html>

【问题讨论】：

在代码开始执行之前，你必须检查$_FILES数组是否设置了isset()函数。
你不能从扩展名中分辨出文件类型，顺便说一句，你在这里犯了一个大错误。

标签： php

【解决方案1】：

你需要移动这个块

$target_dir = "uploads/";
$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
$uploadOk = 1;
$imageFileType = pathinfo($target_file,PATHINFO_EXTENSION);

条件之后的所有内容都进入if(isset($_POST["submit"])) 条件。

第一次下载页面时，$_FILES 为空，但你想使用它。

【讨论】：

【解决方案2】：

检查此代码 - 它现在不应该抛出错误

<!DOCTYPE html>
<html>
<body>

    <form action="<?php $_SERVER['PHP_SELF'] ?>" method="post" enctype="multipart/form-data">
        Select image to upload:
        <input type="file" name="fileToUpload" id="fileToUpload" class="upload_file">
        <input type="submit" value="Upload Image" name="submit">
    </form>
    <?php

    // Check if image file is a actual image or fake image
    if(isset($_POST["submit"])) 
    {

        $target_dir = "uploads/";
        $target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
        $uploadOk = 1;
        $imageFileType = pathinfo($target_file,PATHINFO_EXTENSION);

        $check = getimagesize($_FILES["fileToUpload"]["tmp_name"]);
        if($check !== false) 
        {
            echo "File is an image - " . $check["mime"] . ".";
            echo '<a href="'.$target_file.'">Download you file here</a>';
            $uploadOk = 1;
        } 
        else 
        {
            echo "File is not an image.";
            $uploadOk = 0;
        }

        // Check if file already exists
        if (file_exists($target_file)) 
        {
            echo "Sorry, file already exists.";
            $uploadOk = 0;
        }
        // Check file size
        if ($_FILES["fileToUpload"]["size"] > 500000) 
        {
            echo "Sorry, your file is too large.";
            $uploadOk = 0;
        }
        // Allow certain file formats
        if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg"&&         $imageFileType != "gif" ) 
        {
            echo "Sorry, only JPG, JPEG, PNG & GIF files are allowed.";
            $uploadOk = 0;
        }
        // Check if $uploadOk is set to 0 by an error
        if ($uploadOk == 0) 
        {
            echo "Sorry, your file was not uploaded.";
        // if everything is ok, try to upload file
        } 
        else 
        {
            if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) 
            {
                echo "The file ". basename( $_FILES["fileToUpload"]["name"]). " has been uploaded.";
            } 
            else 
            {
                echo "Sorry, there was an error uploading your file.";
            }
        }
    }
    ?>
</body>
</html>

【讨论】：

太棒了，谢谢。我了解它是如何发送这些错误的。我被困在这个问题上太久了

【解决方案3】：

您应该在代码中区分何时通过 GET（加载表单）加载页面以及何时发出 POST 请求并且您需要处理上传。这适用于与文件上传相关的所有事情。

我通常也会将所有处理都放在顶部，如果您想在成功发布之后进行重定向，这可能会很有用：

if ($_SERVER['REQUEST_METHOD'] === 'POST')
{
  // your upload processing code
}
else
{
  // show your form
}

【讨论】：

OP 使用method="post"。问题是，他想在条件外使用$_FILES。
@lolka_bolka 是的，我刚刚注意到。不过，这仍然是一种更清洁的方法，所以我就让它保持不变。

【解决方案4】：

看看你的代码行：

$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);

将其替换为：

if (isset($_FILES["fileToUpload"]["name"])) {
$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
} else {
var_dump($_FILES);
$target_file = '';
}

这不是完整的解决方案，您的代码中可能还有许多其他错误，但只是从某个地方开始

【讨论】：