PHP直传文件至S3：无需本地存储的策略与实践

<?php
require 'vendor/autoload.php';

use Aws\S3\S3Client;
use Aws\Exception\AwsException;

// 假设文件内容直接作为请求体发送 (例如 Content-Type: application/octet-stream)
// 如果是 multipart/form-data，则需要更复杂的解析逻辑

// 配置S3客户端
$s3Client = new S3Client([
    'version'     => 'latest',
    'region'      => 'your-aws-region', // 例如 'us-east-1'
    'credentials' => [
        'key'    => 'YOUR_AWS_ACCESS_KEY_ID',
        'secret' => 'YOUR_AWS_SECRET_ACCESS_KEY',
    ],
]);

$bucketName = 'your-s3-bucket-name';
$objectKey = 'uploads/example-file-' . uniqid() . '.bin'; // S3中的文件路径和名称

try {
    // 获取 php://input 流
    $bodyStream = fopen('php://input', 'r');

    if ($bodyStream === false) {
        throw new Exception("无法打开 php://input 流");
    }

    // 检查是否有内容，避免上传空文件
    // 注意：对于 multipart/form-data，这里可能包含整个请求体，需要先解析
    // 对于 application/octet-stream，可以直接使用
    $metadata = stream_get_meta_data($bodyStream);
    if ($metadata['unread_bytes'] === 0 && fseek($bodyStream, 0, SEEK_END) === 0 && ftell($bodyStream) === 0) {
        // 如果流是空的，可能不是有效的文件上传
        // 实际应用中，这里需要更严谨的判断
        fclose($bodyStream);
        http_response_code(400);
        echo json_encode(['error' => 'No file content received.']);
        exit;
    }
    fseek($bodyStream, 0); // 重置流指针到开始

    // 使用S3Client的upload方法直接上传流
    $result = $s3Client->upload($bucketName, $objectKey, $bodyStream, 'public-read'); // 'public-read' 权限示例

    // 关闭流
    fclose($bodyStream);

    echo json_encode([
        'message' => 'File uploaded successfully!',
        'url'     => $result['ObjectURL']
    ]);

} catch (AwsException $e) {
    http_response_code(500);
    echo json_encode(['error' => $e->getMessage()]);
} catch (Exception $e) {
    http_response_code(500);
    echo json_encode(['error' => $e->getMessage()]);
}
?>

<?php
require 'vendor/autoload.php';

use Aws\S3\S3Client;
use Aws\CommandPool;
use GuzzleHttp\Psr7\Request;
use Aws\Exception\AwsException;

// 配置S3客户端
$s3Client = new S3Client([
    'version'     => 'latest',
    'region'      => 'your-aws-region', // 例如 'us-east-1'
    'credentials' => [
        'key'    => 'YOUR_AWS_ACCESS_KEY_ID',
        'secret' => 'YOUR_AWS_SECRET_ACCESS_KEY',
    ],
]);

$bucketName = 'your-s3-bucket-name';

// 从前端获取文件名和文件类型
$fileName = $_POST['fileName'] ?? 'untitled-' . uniqid() . '.bin';
$fileType = $_POST['fileType'] ?? 'application/octet-stream';

// 确保文件名在S3中是唯一的或有合适的路径
$objectKey = 'uploads/' . basename($fileName);

try {
    // 创建一个PutObject命令
    $command = $s3Client->getCommand('PutObject', [
        'Bucket'      => $bucketName,
        'Key'         => $objectKey,
        'ContentType' => $fileType,
        'ACL'         => 'public-read', // 示例：设置文件为公开可读
    ]);

    // 生成预签名URL，有效期为10分钟
    $presignedRequest = $s3Client->createPresignedRequest($command, '+10 minutes');

    // 获取预签名URL
    $presignedUrl = (string) $presignedRequest->getUri();

    header('Content-Type: application/json');
    echo json_encode([
        'uploadUrl' => $presignedUrl,
        'objectKey' => $objectKey,
        'fileUrl'   => "https://{$bucketName}.s3.{$s3Client->getRegion()}.amazonaws.com/{$objectKey}" // 如果是public-read
    ]);

} catch (AwsException $e) {
    http_response_code(500);
    echo json_encode(['error' => $e->getMessage()]);
} catch (Exception $e) {
    http_response_code(500);
    echo json_encode(['error' => $e->getMessage()]);
}
?>

document.getElementById('fileInput').addEventListener('change', async (event) => {
    const file = event.target.files[0];
    if (!file) {
        return;
    }

    try {
        // 1. 请求后端获取预签名URL
        const response = await fetch('/get-presigned-url.php', {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json',
            },
            body: JSON.stringify({
                fileName: file.name,
                fileType: file.type,
            }),
        });
        const data = await response.json();

        if (data.error) {
            alert('获取上传URL失败: ' + data.error);
            return;
        }

        const uploadUrl = data.uploadUrl;
        const objectKey = data.objectKey;

        // 2. 使用PUT请求直接上传文件到S3
        const uploadResponse = await fetch(uploadUrl, {
            method: 'PUT',
            headers: {
                'Content-Type': file.type, // 必须与后端生成预签名URL时指定的Content-Type匹配
            },
            body: file, // 直接发送文件对象
        });

        if (uploadResponse.ok) {
            alert('文件上传成功！S3路径: ' + objectKey);
            console.log('文件在S3上的URL:', data.fileUrl);
            // 可以在这里更新UI或通知后端文件已上传
        } else {
            const errorText = await uploadResponse.text();
            alert('文件上传到S3失败: ' + errorText);
        }

    } catch (error) {
        console.error('上传过程中发生错误:', error);
        alert('上传过程中发生错误。');
    }
});

<input type="file" id="fileInput">