// ==UserScript==
// @name PKU-Thesis-Download 北大论文平台下载工具
// @namespace https://greasyfork.org/zh-CN/scripts/442310-pku-thesis-download
// @supportURL https://github.com/xiaotianxt/PKU-Thesis-Download
// @homepageURL https://github.com/xiaotianxt/PKU-Thesis-Download
// @version 1.2.5
// @description 北大论文平台下载工具，请勿传播下载的文件，否则后果自负。
// @author xiaotianxt
// @match http://162.105.134.201/pdfindex*
// @match https://drm.lib.pku.edu.cn/pdfindex*
// @match https://drm-lib-pku-edu-cn-443.webvpn.bjmu.edu.cn/pdfindex*
// @icon https://www.google.com/s2/favicons?sz=64&domain=pku.edu.cn
// @require https://cdnjs.cloudflare.com/ajax/libs/jspdf/2.5.1/jspdf.umd.min.js
// @require https://cdnjs.cloudflare.com/ajax/libs/notify/0.4.2/notify.min.js
// @license GNU GPLv3
// @grant GM_addStyle
// @history 1.2.2 修复了横屏图片的加载样式和pdf渲染样式
// @history 1.2.3 支持北医 Web VPN 系统
// @history 1.2.4 适配限流问题
// @history 1.2.5 适当降低请求频率，避免触发过多限流
// @downloadURL none
// ==/UserScript==
(function () {
"use strict";
class ParallelRateLimiter {
constructor(maxParallel) {
this.queue = [];
this.running = 0;
this.maxParallel = maxParallel;
}
add(fn) {
return new Promise((resolve, reject) => {
const wrappedFn = async () => {
this.running++;
try {
const result = await fn();
resolve(result);
} catch (error) {
reject(error);
} finally {
this.running--;
this.runNext();
}
};
if (this.running < this.maxParallel) {
wrappedFn();
} else {
this.queue.push(wrappedFn);
}
});
}
runNext() {
if (this.queue.length > 0 && this.running < this.maxParallel) {
const nextFn = this.queue.shift();
if (nextFn) {
nextFn();
}
}
}
}
async function retry(fn, retries = 3, initialDelay = 1000) {
let attempt = 0;
while (true) {
try {
return await fn();
} catch (error) {
attempt++;
if (attempt >= retries) {
console.error(`Failed after ${retries} attempts`);
throw error;
}
// 计算指数退避延迟时间: initialDelay * 2^attempt + 随机抖动
const delay = initialDelay * Math.pow(2, attempt) + Math.random() * 1000;
console.warn(`Attempt ${attempt} failed. Retrying in ${Math.round(delay)}ms...`);
await new Promise(resolve => setTimeout(resolve, delay));
}
}
}
const limiter = new ParallelRateLimiter(3);
const print = (...args) => console.log("[PKU-Thesis-Download]", ...args);
const OPTIMIZATION = "pku_thesis_download.optimization";
const fid = $("#fid").val();
const totalPage = parseInt($("#totalPages").html().replace(/ \/ /, ""));
const baseUrl = `/jumpServlet?fid=${fid}`;
const msgBox = initUI();
if (localStorage.getItem(OPTIMIZATION) === "true" || !localStorage.getItem(OPTIMIZATION)) {
optimizeImgLoading();
}
function initUI() {
// 下载按钮
const downloadButton = document.querySelector("#thumbtab").cloneNode(true);
downloadButton.innerHTML = `
下载
`;
document.querySelector("#btnList").appendChild(downloadButton);
downloadButton.addEventListener("click", download);
// 论文加载优化
const optimizeImg = document.querySelector("#thumbtab").cloneNode(true);
optimizeImg.innerHTML = `
`;
optimizeImg.querySelector("input").checked = localStorage.getItem(OPTIMIZATION) === "true" || localStorage.getItem(OPTIMIZATION) === null;
optimizeImg.addEventListener("click", (e) => {
const checked = e.target.checked;
localStorage.setItem(OPTIMIZATION, checked);
if (checked) {
optimizeImg();
}
});
document.querySelector("#btnList").appendChild(optimizeImg);
GM_addStyle(`
.loadingBg {
display: flex;
justify-content: center;
align-items: center;
}
`);
const observer = new MutationObserver((mutationsList) => {
for (let mutation of mutationsList) {
if (mutation.type === 'childList') {
mutation.addedNodes.forEach((node) => {
if (node.nodeName === 'IMG' && node.parentElement.classList.contains('loadingBg')) {
node.addEventListener('load', function () {
const img = node;
if (img.naturalWidth > img.naturalHeight) {
// 横向图片
img.style.height = 'min(100%, 90vw / 1.414)';
img.style.width = 'auto';
}
});
}
});
}
}
});
observer.observe(document.querySelector(".jspPane-scroll"), { childList: true, subtree: true });
// msgBox
const msgBox = downloadButton.querySelector("span");
return msgBox;
}
async function download(e) {
e.preventDefault();
e.target.disabled = true;
await solveSrc().then(solveImg).then(solvePDF);
e.target.disabled = false;
}
/**
* 解析pdf图片链接
*/
async function solveSrc() {
async function downloadSrcInfo(url) {
const res = await fetch(url);
if (!res.ok) {
throw new Error(`HTTP error! status: ${res.status}`);
}
const json = await res.json();
finished += 2;
msgBox.innerHTML = `${finished}/${totalPage}`;
return json.list;
}
let finished = 0;
const tasks = [];
for (let page = 0; page < totalPage; page += 2) {
const url = `${baseUrl}&page=${page}`;
tasks.push(() => retry(async () => downloadSrcInfo(url)));
}
const results = await Promise.all(tasks.map(task => limiter.add(task)));
return results.flat(); // 假设我们想要一个扁平化的结果数组
}
/**
* 下载图片
*/
async function solveImg(urls) {
let numFinished = 0;
async function downloadPdf(url) {
return fetch(url)
.then((res) => res.blob())
.then((blob) => {
const reader = new FileReader();
reader.readAsDataURL(blob);
return new Promise((resolve, reject) => {
reader.onloadend = () => {
const base64 = reader.result;
const img = new Image();
img.src = base64;
img.onload = () => {
const orientation = img.width > img.height ? "landscape" : "portrait";
resolve({ base64, orientation });
numFinished++;
msgBox.innerHTML = numFinished + "/" + numTotal;
};
img.onerror = () => {
console.error("Failed to load image", url);
reject(null);
}
};
});
});
}
// remove duplicated
const map = new Map(urls.flat().map((item) => [item.id, item.src]));
// assert that all pages are loaded
if (map.size !== totalPage) {
const missing = Array.from({ length: totalPage }, (_, i) => i + 1).filter((i) => !map.has(`${i}`));
alert(`部分页面没有加载出来，请联系开发者。\n缺少：${missing.join(",")}`);
}
// sort and clear index
const sortedUrls = [...map.entries()]
.sort((a, b) => a[0] - b[0])
.map((item) => item[1]);
// download images
const tasks = [];
const numTotal = sortedUrls.length;
sortedUrls.forEach((url) => {
tasks.push(async () => await retry(async () => await downloadPdf(url)));
});
return Promise.all(tasks.map(task => limiter.add(task)));
}
/**
* 拼接为pdf
* @param {*} base64s
*/
async function solvePDF(base64s) {
msgBox.innerHTML = "拼接中";
const doc = new jspdf.jsPDF({ format: 'a4', orientation: 'portrait' });
for (let i = 0; i < base64s.length; i++) {
const { base64, orientation } = base64s[i];
if (orientation === "landscape") {
doc.addImage(base64, "JPEG", 0, 0, 297, 210);
} else {
doc.addImage(base64, "JPEG", 0, 0, 210, 297);
}
i + 1 == base64s.length || doc.addPage("a4", base64s[i + 1].orientation);
}
msgBox.innerHTML = "保存中";
doc.save(document.title + ".pdf");
msgBox.innerHTML = "完成！";
}
/**
* 优化加载
*/
async function optimizeImgLoading() {
function loadImgForPage(element, observer) {
const index = Array.from(document.getElementsByClassName('fwr_page_box')).indexOf(element) + 1;
observer.unobserve(element);
if (index % 3 !== 1) return;
print(`load page ${index + 3} - ${index + 5}.`);
omg(index + 3); // 提前加载 3 页
}
// 创建 IntersectionObserver 实例
const observer = new IntersectionObserver((entries, observer) => {
entries.forEach(entry => {
if (entry.isIntersecting) {
loadImgForPage(entry.target, observer);
}
});
}, {
root: document.querySelector('#jspPane'), // 使用 jspPane 作为滚动容器
rootMargin: '0px',
threshold: 0 // 当 10% 的内容进入视口时触发
});
// 为每个 fwr_page_box 元素设置观察器
const pages = document.querySelectorAll('.fwr_page_box:nth-child(3n+1)');
pages.forEach(page => observer.observe(page));
}
})();