php文件上传的两种实现方法

下面是关于php文件上传的两种实现方法的完整攻略。

实现方法一：使用原生的PHP函数

使用原生的PHP函数可以实现文件上传，可以通过以下步骤来实现：

1. 首先在前端页面中添加一个表单，其中包含一个file字段，用于选择文件。

<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>

1. 在上传文件的php脚本中，使用$_FILES超全局变量获取上传的文件信息。

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

1. 判断上传的文件是否是合法的文件类型。

$uploadOk = 1;
$imageFileType = strtolower(pathinfo($target_file, PATHINFO_EXTENSION));
if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg"
&& $imageFileType != "gif" ) {
    echo "Sorry, only JPG, JPEG, PNG & GIF files are allowed.";
    $uploadOk = 0;
}

1. 判断上传的文件是否已经存在，如果存在就提示用户选择其他文件。

if (file_exists($target_file)) {
    echo "Sorry, file already exists.";
    $uploadOk = 0;
}

1. 判断上传文件大小，如果超过规定大小，则提示用户文件太大。

if ($_FILES["fileToUpload"]["size"] > 500000) {
    echo "Sorry, your file is too large.";
    $uploadOk = 0;
}

1. 执行最终的上传操作，如果上传成功，就提示用户文件已经上传成功，如果上传失败，就提示用户上传失败。

if ($uploadOk == 0) {
    echo "Sorry, your file was not uploaded.";
} else {
    if (move_uploaded_file($_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.";
    }
}

实现方法二：使用第三方库

使用第三方库也可以实现文件上传操作，可以通过以下步骤来实现：

1. 首先，在项目目录下使用composer命令来安装第三方库。

composer require symfony/http-foundation

1. 在上传文件的php脚本中，使用这个第三方库来获取上传的文件信息。

$request = Request::createFromGlobals();
$file = $request->files->get('fileToUpload');

1. 使用这个第三方库的上传函数来执行上传操作。

$target_dir = "uploads/";
$target_file = $target_dir . $file->getClientOriginalName();
$file->move($target_dir, $target_file);
echo "The file ". basename( $file->getClientOriginalName()). " has been uploaded.";

示例1：

<?php
require_once __DIR__ . '/vendor/autoload.php';

use Symfony\Component\HttpFoundation\Request;

$request = Request::createFromGlobals();
$file = $request->files->get('fileToUpload');

$target_dir = "uploads/";
$target_file = $target_dir . $file->getClientOriginalName();
$file->move($target_dir, $target_file);
echo "The file ". basename( $file->getClientOriginalName()). " has been uploaded.";
?>

示例2：

<?php
$target_dir = "uploads/";
$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
$uploadOk = 1;
$imageFileType = strtolower(pathinfo($target_file,PATHINFO_EXTENSION));
if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg"
&& $imageFileType != "gif" ) {
    echo "Sorry, only JPG, JPEG, PNG & GIF files are allowed.";
    $uploadOk = 0;
}
if (file_exists($target_file)) {
    echo "Sorry, file already exists.";
    $uploadOk = 0;
}
if ($_FILES["fileToUpload"]["size"] > 500000) {
    echo "Sorry, your file is too large.";
    $uploadOk = 0;
}
if ($uploadOk == 0) {
    echo "Sorry, your file was not uploaded.";
} 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.";
    }
}
?>

希望这些步骤对您有所帮助！