PHP文件上传-PHP合辑2-高级进阶

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您是否曾经想知道PHP是如何构建文件上传系统的？在这里，我们将了解文件上传过程。您可能会问：“我们能否使用此系统上传任何类型的文件？”。答案是肯定的，我们可以上传不同扩展名的文件。

方法：要运行PHP脚本，我们需要服务器。因此，请确保在您的Windows计算机上安装了XAMPP服务器或WAMP服务器。

HTML代码片段：以下是将文件上传到服务器所需的HTML表单的HTML源代码。在HTML的<form>标签中，我们使用“enctype=’multipart/form-data’”，这是一种允许通过POST方法发送文件的编码类型。没有这种编码，文件无法通过POST方法发送。如果您希望允许用户通过表单上传文件，则必须使用此enctype。

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>File Upload Form</title>
</head>
<body>
    <form action="file-upload-manager.php" method="post" enctype="multipart/form-data">
    <!--multipart/form-data ensures that form data is going to be encoded as MIME data-->
        <h2>Upload File</h2>
        <label for="fileSelect">Filename:</label>
        <input type="file" name="photo" id="fileSelect">
        <input type="submit" name="submit" value="Upload">
        <!-- name of the input fields are going to be used in our php script-->
<p><strong>Note:</strong>Only .jpg, .jpeg, .png formats allowed to a max size of 2MB.</p>
    </form>
</body>
</html>

现在，我们来编写一个能够处理文件上传系统的PHP脚本。 file-upload-manager.php

<?php
// Check if the form was submitted
if($_SERVER["REQUEST_METHOD"] == "POST")
{
    // Check if file was uploaded without errors
    if (isset($_FILES["photo"]) && $_FILES["photo"]["error"] == 0)
    {
        $allowed_ext = array("jpg" => "image/jpg",
                            "jpeg" => "image/jpeg",
                            "gif" => "image/gif",
                            "png" => "image/png");
        $file_name = $_FILES["photo"]["name"];
        $file_type = $_FILES["photo"]["type"];
        $file_size = $_FILES["photo"]["size"];
        // Verify file extension
        $ext = pathinfo($filename, PATHINFO_EXTENSION);
        if (!array_key_exists($ext, $allowed_ext))    
            die("Error: Please select a valid file format.");
        // Verify file size - 2MB max
        $maxsize = 2 * 1024 * 1024;
        if ($file_size > $maxsize)    
            die("Error: File size is larger than the allowed limit of 2MB");    
        // Verify MYME type of the file
        if (in_array($file_type, $allowed_ext))
        {
            // Check whether file exists before uploading it
            if (file_exists("upload/".$_FILES["photo"]["name"]))        
                echo $_FILES["photo"]["name"]." already exists!";
            else
            {
                move_uploaded_file($_FILES["photo"]["tmp_name"],
                        "uploads/".$_FILES["photo"]["name"]);
                echo "Your file uploaded successfully.";
            }
        }
        else
        {
            echo "Error: Please try again!";
        }
    }
    else
    {
        echo "Error: ". $_FILES["photo"]["error"];
    }
}
?>