PHP file upload guide: How to use the move_uploaded_file function to handle uploaded files

PHP File Upload Guide: How to use the move_uploaded_file function to process uploaded files

In developing web applications, file uploading is a common requirement. PHP provides a convenient function move_uploaded_file() for processing uploaded files. This article will introduce you how to use this function to implement the file upload function.

1. Preparation

Before you start, make sure that your PHP environment has been configured with file upload parameters. You can confirm this by opening the php.ini file and looking for the "file_uploads" parameter. If the value of this parameter is "Off", please change it to "on", save the file and restart the server.

2. Create a file upload form

First, we need to create a file upload input field in the HTML form. The following is a simple example:

<form action="upload.php" method="post" enctype="multipart/form-data">
    <input type="file" name="fileToUpload" id="fileToUpload">
    <input type="submit" value="上传文件" name="submit">
</form>

In the above code, we use enctype="multipart/form-data" to specify that the form contains an input field for file upload .

3. Process file upload requests

Next, we need to create a PHP script to process file upload requests. In this script, we will use the move_uploaded_file() function to save the uploaded file. The following is a basic example:

<?php
$targetDir = "uploads/";

if(isset($_POST["submit"])){
    $targetFile = $targetDir . basename($_FILES["fileToUpload"]["name"]);
    $uploadOk = 1;
    $imageFileType = strtolower(pathinfo($targetFile,PATHINFO_EXTENSION));

    // 检查文件是否已经存在
    if (file_exists($targetFile)) {
        echo "文件已经存在。";
        $uploadOk = 0;
    }
  
    // 检查文件大小
    if ($_FILES["fileToUpload"]["size"] > 500000) {
        echo "文件大小超过限制。";
        $uploadOk = 0;
    }

    // 允许的文件格式
    if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg"
    && $imageFileType != "gif" ) {
        echo "只允许上传JPG, JPEG, PNG, GIF格式的文件。";
        $uploadOk = 0;
    }

    // 检查上传是否成功
    if ($uploadOk == 0) {
        echo "文件上传失败。";
    } else {
        if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $targetFile)) {
            echo "文件上传成功。";
        } else {
            echo "文件上传失败。";
        }
    }
}
?>

In the above code, we first define a target folder $targetDir to store uploaded files. Then, we obtain the information of the uploaded file through $_FILES["fileToUpload"], and use the basename() function to obtain the file name of the uploaded file.

Next, we perform some checks on the uploaded files, such as determining whether the file already exists, whether the file size exceeds the limit, and whether the file format meets the requirements. If the check passes, we can use the move_uploaded_file() function to move the file from the temporary directory to the target folder.

4. Display the upload results

Finally, we can display the upload results by outputting the results on the file upload form page. The following is a simple example:

<?php
if(isset($_FILES["fileToUpload"]["name"])) {
    echo "上传的文件名：" . $_FILES["fileToUpload"]["name"] . "<br>";
    echo "文件类型：" . $_FILES["fileToUpload"]["type"] . "<br>";
    echo "文件大小：" . ($_FILES["fileToUpload"]["size"] / 1024) . " KB<br>";
}
?>

The above code will display the uploaded file name, file type and file size after the file upload is completed.

Summary

By using the move_uploaded_file() function, we can easily handle the file upload function in PHP. In a real application, you might also add more validation logic and file processing operations to meet your specific needs. At the same time, you must also pay attention to security protection measures, such as only allowing specified types to be uploaded, limiting the size of uploaded files, etc. I hope this article helps you understand how to use the move_uploaded_file() function to handle file uploads.

Reference link:

• PHP official documentation: https://www.php.net/manual/en/function.move-uploaded-file.php

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