How to implement file upload in PHP

How does PHP implement file upload? This article will introduce you to the method of uploading files in PHP through code examples. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

Here we use PHP's global array $_FILES to upload files:

• ##$_FILES["file"]["name"] - The name of the uploaded file

• $_FILES["file"]["type"] - The type of the uploaded file

• $_FILES["file"]["size"] - The size of the uploaded file, in bytes

• $_FILES[ "file"]["tmp_name"] - The name of the temporary copy of the file stored on the server

• $_FILES["file"]["error"] - Error code caused by file upload

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HTML code:

<form action="upload_file.php" method="post" enctype="multipart/form-data">
    <label for="file">Filename:</label>
    <input type="file" name="file" id="file" /><br />
    <input type="submit" name="submit" value="Submit" />
</form>

PHP code:

if (!empty($_FILES)) {
 
    // 限制文件大小
    $file_size = $_FILES["file"]["size"];
    // 限制2M大小
    if ($file_size > 1024 * 1024 * 2) {
        echo '文件大小超过限制';
        exit;
    }
 
    // 限制文件上传类型
    $file_type = $_FILES["file"]["type"];
    $file_type_arr = ['image/jpg', 'image/jpeg', 'image/png', 'image/pjpeg', 'image/gif'];
    if (!in_array($file_type, $file_type_arr)) {
        echo '上传文件类型错误';
        exit;
    }
 
    // 文件上传到服务器临时文件夹之后的文件名
    $tem_name = $_FILES['file']['tmp_name'];
    // 取得文件后缀名
    $file_fix = explode('.', $_FILES['file']['name'])[1] ? explode('.', $_FILES['file']['name'])[1] : 'png';
    // 文件重命名，这里自动生成一个不重复的名字，方便使用
    $name = md5(uniqid(md5(microtime(true)), true)) . '.' . $file_fix;
    // 要存放文件的目录定义，这里按日期分开存储
    $file_dir = dirname(__FILE__) . '/upload/' . date('Ymd') . '/';
    // 检测要存放文件的目录是否存在，不存在则创建
    if (!is_dir($file_dir)) {
        mkdir($file_dir, 0755, true);
    }
    // 移动文件到指定目录下
    @ move_uploaded_file($tem_name, $file_dir . $name);
 
    echo '上传成功';
    exit;
} else {
    echo '文件上传失败';
    exit;
}

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