http://www.shuge.org/meet/...ic/214292/

今天看到有书友询问该网址的书怎么下载，抱着好奇的态度便探索了一番。

media.hkpl.gov.hk/api/d...6647617538

我们可以看到这个load?id=xxxx，指向的确实是一个pdf文档，但是我们正常情况下打开是显示：This page is not allowed to be this website.

推测可能是有某种检测或者冲突，直接打开缺少必要条件是浏览不了的。

写不下去了，个人的思路是编写一个油猴脚本。

// ==UserScript==
// @name HKPL PDF Parallel Downloader
// @namespace hkpl-pdf-parallel-downloader
// @version 0.5
// @match sls.hkpl.gov.hk/digit...ewer.html*
// @run-at document-idle
// @grant none
// ==/UserScript==

(function () {
'use strict';

const CONCURRENCY = 16; // 并发数，可改 8 / 16 / 24
const CHUNK_MB = 4; // 每个分片大小，可改 4 / 8 / 16

function getPdfUrl() {
return new URLSearchParams(location.search).get('file');
}

function filenameFromUrl(url) {
const u = new URL(url);
return hkpl_${u.searchParams.get('id') || Date.now()}.pdf;
}

function mb(n) {
return ${(n / 1024 / 1024).toFixed(1)} MB;
}

function createPanel() {
const box = document.createElement('div');
box.style.cssText = `
position: fixed;
right: 80px;
top: 10px;
z-index: 999999;
width: 280px;
padding: 10px;
background: white;
border: 1px solid #ccc;
border-radius: 8px;
box-shadow: 0 3px 12px rgba(0,0,0,.25);
font-size: 13px;
color: #222;

;

const btn = document.createElement('button');
btn.textContent = '并发下载PDF';
btn.style.cssText = 

width: 100%;
padding: 8px;
border: 0;
border-radius: 6px;
background: #0b57d0;
color: white;
cursor: pointer;
font-size: 14px;

;

const text = document.createElement('div');
text.textContent = '等待下载';
text.style.cssText = <code>margin-top: 8px;</code>;

const barWrap = document.createElement('div');
barWrap.style.cssText = 

margin-top: 8px;
width: 100%;
height: 8px;
background: #e5e7eb;
border-radius: 999px;
overflow: hidden;

;

const bar = document.createElement('div');
bar.style.cssText = 

width: 0%;
height: 100%;
background: #0b57d0;
transition: width .15s linear;
`;

barWrap.appendChild(bar);
box.appendChild(btn);
box.appendChild(text);
box.appendChild(barWrap);
document.body.appendChild(box);

return { btn, text, bar };
}

async function detectSize(url) {
const res = await fetch(url, {
method: 'GET',
credentials: 'include',
cache: 'no-store',
headers: {
Accept: 'application/pdf,*/*',
Range: 'bytes=0-0'
}
});

const contentRange = res.headers.get('content-range') || '';
const match = contentRange.match(/\/(\d+)$/);

if (res.status === 206 && match) {
return Number(match[1]);
}

const len = Number(res.headers.get('content-length') || 0);
if (res.status === 200 && len > 0) {
throw new Error('服务器忽略 Range 请求，不能并发分段下载，只能单连接。');
}

const text = await res.clone().text().catch(() => '');
throw new Error(无法检测 PDF 大小。HTTP ${res.status}\n${text.slice(0, 300)});
}

async function fetchPart(url, start, end, onProgress) {
const res = await fetch(url, {
method: 'GET',
credentials: 'include',
cache: 'no-store',
headers: {
Accept: 'application/pdf,*/*',
Range: bytes=${start}-${end}
}
});

if (res.status !== 206) {
const text = await res.clone().text().catch(() => '');
throw new Error(分片请求失败 HTTP ${res.status}\n${text.slice(0, 200)});
}

const reader = res.body.getReader();
const chunks = [];
let received = 0;

while (true) {
const { done, value } = await reader.read();
if (done) break;
chunks.push(value);
received += value.length;
onProgress(value.length);
}

const expected = end - start + 1;
if (received !== expected) {
throw new Error(分片大小不一致：expected ${expected}, got ${received});
}

return new Blob(chunks, { type: 'application/pdf' });
}

async function parallelDownload(ui) {
const url = getPdfUrl();
if (!url) throw new Error('没有找到 viewer.html 的 file 参数');

ui.btn.disabled = true;
ui.btn.textContent = '检测大小...';
ui.text.textContent = '正在检测服务器是否支持分段下载...';

const total = await detectSize(url);
const filename = filenameFromUrl(url);
const chunkSize = CHUNK_MB * 1024 * 1024;

const ranges = [];
for (let start = 0; start < total; start += chunkSize) {
const end = Math.min(start + chunkSize - 1, total - 1);
ranges.push({ index: ranges.length, start, end });
}

ui.btn.textContent = '下载中...';

let downloaded = 0;
const startedAt = performance.now();
const parts = new Array(ranges.length);
let next = 0;

function updateProgress(delta) {
downloaded += delta;
const percent = downloaded / total * 100;
const seconds = Math.max((performance.now() - startedAt) / 1000, 0.001);
const speed = downloaded / seconds / 1024 / 1024;

ui.bar.style.width = ${percent.toFixed(2)}%;
ui.text.textContent =
${mb(downloaded)} / ${mb(total)} (${percent.toFixed(1)}%) ${speed.toFixed(2)} MB/s;
}

async function worker() {
while (next < ranges.length) {
const item = ranges[next++];
const blob = await fetchPart(url, item.start, item.end, updateProgress);
parts[item.index] = blob;
}
}

const workerCount = Math.min(CONCURRENCY, ranges.length);
ui.text.textContent = 并发 ${workerCount}，共 ${ranges.length} 个分片...;

await Promise.all(Array.from({ length: workerCount }, worker));

ui.text.textContent = '正在合并 PDF...';

const finalBlob = new Blob(parts, { type: 'application/pdf' });
if (finalBlob.size !== total) {
throw new Error(合并后大小不一致：expected ${total}, got ${finalBlob.size});
}

const objectUrl = URL.createObjectURL(finalBlob);
const a = document.createElement('a');
a.href = objectUrl;
a.download = filename;
document.body.appendChild(a);
a.click();
a.remove();

setTimeout(() => URL.revokeObjectURL(objectUrl), 60000);

ui.bar.style.width = '100%';
ui.text.textContent = 下载成功：${mb(finalBlob.size)};
ui.btn.textContent = '下载成功';
}

const ui = createPanel();

ui.btn.onclick = async () => {
try {
await parallelDownload(ui);
} catch (e) {
console.error('[HKPL] parallel download failed:', e);
ui.btn.disabled = false;
ui.btn.textContent = '重新下载';
ui.text.textContent = '下载失败';
alert(下载失败：\n${e.message});
}
};

console.log('[HKPL] parallel downloader ready:', getPdfUrl());
})();

正常启用的情况下是能看到这个组件的，如果没有的话可以多刷新几下。脚本由Chatgpt编写。

注意事项的话，就是关闭代理，切换一个好的网络环境，最好是用手机热点，不然有概率会出现下载速度为0.06mb/s，下半天都没成功。

也尝试使用了python脚本进行下载，能成功，但是下载速度很慢，应该跟我网络有关。