PHP怎样处理大文件上传？分片上传实现方法

php.ini

upload_max_filesize

post_max_size

memory_limit

max_execution_time

File

Blob.prototype.slice()

<input type="file">

File

File

Blob

slice(start, end)

FormData

// 伪代码示例，实际应用需要更健壮的错误处理和进度管理
function uploadFileInChunks(file) {
    const chunkSize = 1 * 1024 * 1024; // 1MB
    let currentChunk = 0;
    const totalChunks = Math.ceil(file.size / chunkSize);
    const fileIdentifier = file.name + '-' + file.size + '-' + file.lastModified; // 简单唯一标识

    const uploadNextChunk = () => {
        if (currentChunk < totalChunks) {
            const start = currentChunk * chunkSize;
            const end = Math.min(file.size, start + chunkSize);
            const chunk = file.slice(start, end);

            const formData = new FormData();
            formData.append('file_chunk', chunk);
            formData.append('file_identifier', fileIdentifier);
            formData.append('chunk_index', currentChunk);
            formData.append('total_chunks', totalChunks);

            fetch('/upload-chunk.php', {
                method: 'POST',
                body: formData
            })
            .then(response => response.json())
            .then(data => {
                if (data.success) {
                    console.log(`Chunk ${currentChunk} uploaded.`);
                    currentChunk++;
                    uploadNextChunk(); // 上传下一个分片
                } else {
                    console.error(`Chunk ${currentChunk} failed:`, data.message);
                    // 考虑重试机制
                }
            })
            .catch(error => {
                console.error('Network error during chunk upload:', error);
                // 考虑重试机制
            });
        } else {
            console.log('All chunks uploaded. Server will merge.');
            // 通知服务器合并，或者服务器自己判断完成
        }
    };

    uploadNextChunk(); // 开始上传
}

file_identifier

chunk_index

total_chunks

XMLHttpRequest

progress

localStorage

chunk_index

move_uploaded_file

<?php
// upload-chunk.php
// 假设错误处理和验证已在实际应用中实现

$fileIdentifier = $_POST['file_identifier'] ?? '';
$chunkIndex = (int)($_POST['chunk_index'] ?? 0);
$totalChunks = (int)($_POST['total_chunks'] ?? 0);
$uploadedFile = $_FILES['file_chunk'] ?? null;

if (!$uploadedFile || $uploadedFile['error'] !== UPLOAD_ERR_OK) {
    echo json_encode(['success' => false, 'message' => 'File upload error.']);
    exit;
}

$tempDir = 'uploads/chunks/' . $fileIdentifier . '/';
if (!is_dir($tempDir)) {
    mkdir($tempDir, 0777, true); // 确保目录存在
}

$chunkFilePath = $tempDir . $chunkIndex . '.part'; // 临时分片文件命名

if (move_uploaded_file($uploadedFile['tmp_name'], $chunkFilePath)) {
    // 检查所有分片是否都已上传
    $uploadedCount = 0;
    for ($i = 0; $i < $totalChunks; $i++) {
        if (file_exists($tempDir . $i . '.part')) {
            $uploadedCount++;
        }
    }

    if ($uploadedCount === $totalChunks) {
        // 所有分片都已上传，开始合并
        $finalFileName = str_replace(['/', '\', '..'], '', $fileIdentifier); // 简单净化文件名
        $finalFilePath = 'uploads/final/' . $finalFileName;

        $outputHandle = fopen($finalFilePath, 'wb'); // 以二进制写入模式打开最终文件

        if ($outputHandle === false) {
            echo json_encode(['success' => false, 'message' => 'Could not open final file for writing.']);
            exit;
        }

        for ($i = 0; $i < $totalChunks; $i++) {
            $partPath = $tempDir . $i . '.part';
            $inputHandle = fopen($partPath, 'rb');
            if ($inputHandle === false) {
                // 某个分片丢失或无法读取，这通常不应该发生如果uploadedCount检查通过
                fclose($outputHandle);
                unlink($finalFilePath); // 删除不完整的文件
                echo json_encode(['success' => false, 'message' => 'Missing chunk ' . $i]);
                exit;
            }
            while (!feof($inputHandle)) {
                fwrite($outputHandle, fread($inputHandle, 8192)); // 每次读取8KB写入
            }
            fclose($inputHandle);
            unlink($partPath); // 删除已合并的分片
        }
        fclose($outputHandle);
        rmdir($tempDir); // 删除临时目录

        echo json_encode(['success' => true, 'message' => 'File merged successfully.', 'filePath' => $finalFilePath]);
    } else {
        echo json_encode(['success' => true, 'message' => 'Chunk uploaded, waiting for others.']);
    }
} else {
    echo json_encode(['success' => false, 'message' => 'Failed to move uploaded chunk.']);
}
?>