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🗣 Wd提问: php分页断点续传

🤖 Ai回答:
在PHP中实现分页断点续传，通常用于处理大量数据的分页查询或文件传输。以下是几种常见场景下的实现方式：

1、数据库分页断点续传

基础分页（推荐使用LIMIT/OFFSET）
php
<?php
class Pagination {
private $pdo;
private $perPage = 20;

public function __construct($pdo) {
$this-pdo = $pdo;
}

// 获取分页数据
public function getPageData($page, $orderBy = 'id', $orderDirection = 'ASC') {
$offset = ($page 1) * $this-perPage;

$sql = SELECT * FROM your_table
ORDER BY {$orderBy} {$orderDirection}
LIMIT :limit OFFSET :offset;

$stmt = $this-pdo-prepare($sql);
$stmt-bindValue(':limit', $this-perPage, PDO::PARAM_INT);
$stmt-bindValue(':offset', $offset, PDO::PARAM_INT);
$stmt-execute();

return $stmt-fetchAll(PDO::FETCH_ASSOC);
}

// 获取总记录数
public function getTotalCount() {
$stmt = $this-pdo-query(SELECT COUNT(*) as total FROM your_table);
return $stmt-fetch()['total'];
}

// 获取分页信息
public function getPaginationInfo($currentPage) {
$total = $this-getTotalCount();
$totalPages = ceil($total / $this-perPage);

return [
'current_page' = $currentPage,
'total_pages' = $totalPages,
'total_items' = $total,
'has_next' = $currentPage < $totalPages,
'has_prev' = $currentPage 1
];
}
}

// 使用示例
$pdo = new PDO($dsn, $user, $pass);
$pagination = new Pagination($pdo);

$page = isset($_GET['page']) ? (int)$_GET['page'] : 1;
$data = $pagination-getPageData($page);
$paginationInfo = $pagination-getPaginationInfo($page);
?

断点续传优化（基于游标）
php
<?php
class CursorPagination {
private $pdo;
private $perPage = 20;

public function __construct($pdo) {
$this-pdo = $pdo;
}

// 使用游标进行断点续传
public function getPageData($cursor = null, $direction = 'forward') {
$sql = SELECT * FROM your_table
WHERE id :cursor
ORDER BY id ASC
LIMIT :limit;

if ($direction === 'backward') {
$sql = SELECT * FROM your_table
WHERE id < :cursor
ORDER BY id DESC
LIMIT :limit;
}

$stmt = $this-pdo-prepare($sql);
$stmt-bindValue(':cursor', $cursor ?: 0, PDO::PARAM_INT);
$stmt-bindValue(':limit', $this-perPage, PDO::PARAM_INT);
$stmt-execute();

return $stmt-fetchAll(PDO::FETCH_ASSOC);
}

// 获取游标值
public function getCursor($data) {
if (empty($data)) return null;
return end($data)['id'];
}
}
?

2、文件传输断点续传

服务器端实现
php
<?php
class FileTransfer {
private $uploadDir = '/path/to/uploads/';
private $chunkSize = 1024 * 1024; // 1MB

public function uploadChunk($fileId, $chunkNumber, $chunkData) {
$tempFile = $this-uploadDir 、{$fileId}_temp;

// 创建临时文件
if (!file_exists($tempFile)) {
file_put_contents($tempFile, '');
}

// 写入分块
$offset = ($chunkNumber 1) * $this-chunkSize;
$handle = fopen($tempFile, 'r+');
fseek($handle, $offset);
fwrite($handle, $chunkData);
fclose($handle);

return true;
}

public function finalizeUpload($fileId, $totalChunks) {
$tempFile = $this-uploadDir 、{$fileId}_temp;
$finalFile = $this-uploadDir 、$fileId;

// 合并所有分块
for ($i = 1; $i <= $totalChunks; $i++) {
$chunkFile = $this-uploadDir 、{$fileId}_chunk_{$i};
if (file_exists($chunkFile)) {
file_put_contents($finalFile, file_get_contents($chunkFile), FILE_APPEND);
unlink($chunkFile);
}
}

// 清理临时文件
if (file_exists($tempFile)) {
unlink($tempFile);
}

return true;
}

public function resumeUpload($fileId) {
$tempFile = $this-uploadDir 、{$fileId}_temp;

if (!file_exists($tempFile)) {
return ['status' = 'not_started'];
}

$size = filesize($tempFile);
$chunksCompleted = floor($size / $this-chunkSize);

return [
'status' = 'in_progress',
'completed_chunks' = $chunksCompleted,
'total_size' = $size,
'remaining_chunks' = $chunksCompleted + 1
];
}
}
?

客户端JavaScript实现
javascript
class ChunkUploader {
constructor(file, chunkSize = 1024 * 1024) {
this.file = file;
this.chunkSize = chunkSize;
this.uploadedChunks = [];
this.totalChunks = Math.ceil(file.size / chunkSize);
}

async upload() {
const fileReader = new FileReader();

// 检查是否可以恢复上传
const resumeInfo = await this.checkResume();
if (resumeInfo.status === 'in_progress') {
console.log('Resuming upload from chunk:', resumeInfo.completed_chunks);
this.uploadedChunks = Array(resumeInfo.completed_chunks).fill(true);
}

for (let i = 0; i < this.totalChunks; i++) {
if (this.uploadedChunks[i]) continue;

const start = i * this.chunkSize;
const end = Math.min(start + this.chunkSize, this.file.size);
const chunk = this.file.slice(start, end);

try {
await this.uploadChunk(i + 1, chunk);
this.uploadedChunks[i] = true;
console.log(`Uploaded chunk ${i + 1}/${this.totalChunks}`);
} catch (error) {
console.error('Upload failed:', error);
break;
}
}

if (this.uploadedChunks.length === this.totalChunks) {
await this.finalizeUpload();
}
}

async uploadChunk(chunkNumber, chunk) {
const formData = new FormData();
formData.append('file_id', this.file.name);
formData.append('chunk_number', chunkNumber);
formData.append('chunk_data', chunk);

const response = await fetch('/upload.php', {
method: 'POST',
body: formData
});

return response.json();
}

async checkResume() {
const response = await fetch(`/upload.php?check_resume=${this.file.name}`);
return response.json();
}

async finalizeUpload() {
const response = await fetch('/upload.php', {
method: 'POST',
body: JSON.stringify({
action: 'finalize',
file_id: this.file.name
})
});
return response.json();
}
}

3、完整的分页API示例

php
<?php
header('Content-Type: application/json');

class APIPagination {
private $pdo;

public function __construct($pdo) {
$this-pdo = $pdo;
}

public function handleRequest() {
$action = $_GET['action'] ?? 'list';

switch ($action) {
case 'list':
$this-getList();
break;
case 'resume':
$this-resumeList();
break;
default:
$this-error('Invalid action');
}
}

private function getList() {
$page = max(1, (int)($_GET['page'] ?? 1));
$perPage = min(100, (int)($_GET['per_page'] ?? 20));
$orderBy = $_GET['order_by'] ?? 'id';
$orderDir = strtoupper($_GET['order_dir'] ?? 'ASC');

// 验证排序字段
$allowedFields = ['id', 'name', 'created_at'];
if (!in_array($orderBy, $allowedFields)) {
$orderBy = 'id';
}

$offset = ($page 1) * $perPage;

$sql = SELECT * FROM your_table
ORDER BY {$orderBy} {$orderDir}
LIMIT :limit OFFSET :offset;

$stmt = $this-pdo-prepare($sql);
$stmt-bindValue(':limit', $perPage, PDO::PARAM_INT);
$stmt-

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