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php实现文件上传

2026-02-27 10:23:27PHP

文件上传的基本实现

使用PHP实现文件上传需要处理HTML表单和服务器端脚本。HTML表单需要设置enctype="multipart/form-data"属性，PHP通过$_FILES超全局数组接收上传的文件。

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

PHP脚本中检查文件是否存在并处理上传：

$targetDir = "uploads/";
$targetFile = $targetDir . basename($_FILES["fileToUpload"]["name"]);

if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $targetFile)) {
    echo "The file has been uploaded.";
} else {
    echo "Sorry, there was an error uploading your file.";
}

文件验证与安全措施

上传文件时需验证文件类型和大小，防止恶意文件上传。检查文件的MIME类型和扩展名是否合法。

$allowedTypes = ['image/jpeg', 'image/png'];
$fileType = $_FILES["fileToUpload"]["type"];

if (!in_array($fileType, $allowedTypes)) {
    die("Invalid file type.");
}

$maxFileSize = 2 * 1024 * 1024; // 2MB
if ($_FILES["fileToUpload"]["size"] > $maxFileSize) {
    die("File size exceeds the limit.");
}

生成唯一文件名避免冲突：

$fileExtension = pathinfo($_FILES["fileToUpload"]["name"], PATHINFO_EXTENSION);
$newFileName = uniqid() . '.' . $fileExtension;
$targetFile = $targetDir . $newFileName;

错误处理与反馈

检查上传过程中的错误代码，提供详细的错误反馈。

if ($_FILES["fileToUpload"]["error"] !== UPLOAD_ERR_OK) {
    switch ($_FILES["fileToUpload"]["error"]) {
        case UPLOAD_ERR_INI_SIZE:
            die("The uploaded file exceeds the upload_max_filesize directive in php.ini.");
        case UPLOAD_ERR_FORM_SIZE:
            die("The uploaded file exceeds the MAX_FILE_SIZE directive in the HTML form.");
        case UPLOAD_ERR_PARTIAL:
            die("The uploaded file was only partially uploaded.");
        case UPLOAD_ERR_NO_FILE:
            die("No file was uploaded.");
        case UPLOAD_ERR_NO_TMP_DIR:
            die("Missing a temporary folder.");
        case UPLOAD_ERR_CANT_WRITE:
            die("Failed to write file to disk.");
        case UPLOAD_ERR_EXTENSION:
            die("A PHP extension stopped the file upload.");
    }
}

多文件上传处理

支持同时上传多个文件，使用数组形式的文件输入名称。

<input type="file" name="filesToUpload[]" id="filesToUpload" multiple>

PHP脚本中遍历处理每个文件：

foreach ($_FILES["filesToUpload"]["tmp_name"] as $key => $tmpName) {
    $targetFile = $targetDir . basename($_FILES["filesToUpload"]["name"][$key]);
    if (move_uploaded_file($tmpName, $targetFile)) {
        echo "The file " . htmlspecialchars(basename($_FILES["filesToUpload"]["name"][$key])) . " has been uploaded.<br>";
    }
}

php实现文件上传