用于下载超星学习通课件
// ==UserScript==
// @name Chaoxing Downloader
// @namespace http://tampermonkey.net/
// @version 1.0
// @description 用于下载超星学习通课件
// @author Twist Mark
// @match *://*.chaoxing.com/*
// @grant none
// @license MIT
// ==/UserScript==
(function() {
'use strict';
const PDF_LIBRARY_URL = 'https://cdnjs.cloudflare.com/ajax/libs/jspdf/2.5.1/jspdf.umd.min.js';
const SCROLL_THRESHOLD = 50;
const STABILIZE_WAIT_MS = 3000;
const MAX_RETRIES = 5;
const RETRY_DELAY = 1500;
let isRunning = false;
let stabilizeTimer = null;
function loadJsPDF() {
return new Promise((resolve, reject) => {
if (typeof window.jspdf !== 'undefined' && typeof window.jspdf.jsPDF === 'function') {
return resolve();
}
const script = document.createElement('script');
script.src = PDF_LIBRARY_URL;
script.onload = resolve;
script.onerror = reject;
document.head.appendChild(script);
});
}
function showStatus(text, color = '#333') {
let el = document.getElementById('cx-pdf-status');
if (!el) {
el = document.createElement('div');
el.id = 'cx-pdf-status';
el.style.cssText = 'position:fixed; top:10px; right:10px; padding:8px 12px; background:rgba(255,255,255,0.95); border:1px solid #ccc; border-radius:4px; z-index:999999; font-size:12px; color:#333; box-shadow:0 2px 8px rgba(0,0,0,0.2); font-family: sans-serif;';
document.body.appendChild(el);
}
el.style.color = color;
el.innerHTML = `📄 <b>${text}</b>`;
}
async function fetchWithRetry(url, pageNum) {
let retries = 0;
while (retries <= MAX_RETRIES) {
try {
const response = await fetch(url);
if (response.ok) {
return response;
} else if (response.status === 404) {
if (retries < MAX_RETRIES) {
showStatus(`第 ${pageNum} 页未就绪，等待重试 (${retries+1}/${MAX_RETRIES})...`, '#d35400');
await new Promise(r => setTimeout(r, RETRY_DELAY));
retries++;
} else {
return response;
}
} else {
return response;
}
} catch (err) {
retries++;
await new Promise(r => setTimeout(r, RETRY_DELAY));
}
}
throw new Error(`Failed to fetch ${url}`);
}
async function startDownloadProcess() {
isRunning = true;
window.removeEventListener('scroll', handleScroll);
document.body.removeEventListener('scroll', handleScroll);
showStatus('检测到触底，正在分析图片链接...', 'blue');
try {
await loadJsPDF();
const firstImg = document.querySelector("#anchor1 > img") || document.querySelector("img[src*='/thumb/']");
if (!firstImg) {
showStatus('❌ 未找到任何课件图片', 'red');
return;
}
const fullUrl = firstImg.src;
const urlMatch = fullUrl.match(/^(.*)\/thumb\/\d+\.png/i);
if (!urlMatch || !urlMatch[1]) {
showStatus('❌ 图片 URL 格式不支持', 'red');
return;
}
const IMAGE_HEADER_URL = urlMatch[1];
let DOC_ID = 'doc';
const idMatch = IMAGE_HEADER_URL.match(/([0-9a-f]{32})$/i);
if (idMatch) DOC_ID = idMatch[1];
let doc = null;
let pageNum = 1;
let hasMore = true;
const downloadedImages = [];
const MAX_PAGES = 1000;
showStatus('🚀 开始下载...', 'blue');
while (hasMore && pageNum <= MAX_PAGES) {
const currentUrl = `${IMAGE_HEADER_URL}/thumb/${pageNum}.png`;
try {
const response = await fetchWithRetry(currentUrl, pageNum);
if (response.ok) {
const blob = await response.blob();
downloadedImages.push({ blob: blob, page: pageNum });
showStatus(`已下载 ${pageNum} 页...`, '#2980b9');
pageNum++;
} else {
hasMore = false;
}
} catch (err) {
hasMore = false;
}
await new Promise(r => setTimeout(r, 50));
}
if (downloadedImages.length === 0) {
showStatus('下载失败：0张图片', 'red');
return;
}
showStatus(`📦 正在打包 ${downloadedImages.length} 页 PDF...`, '#8e44ad');
for (let i = 0; i < downloadedImages.length; i++) {
const item = downloadedImages[i];
const imgData = await new Promise(resolve => {
const reader = new FileReader();
reader.onload = () => resolve(reader.result);
reader.readAsDataURL(item.blob);
});
const img = new Image();
img.src = imgData;
await new Promise(r => img.onload = r);
const w = img.width;
const h = img.height;
const orientation = w > h ? 'l' : 'p';
if (i === 0) {
doc = new window.jspdf.jsPDF({
orientation: orientation,
unit: 'px',
format: [w, h]
});
} else {
doc.addPage([w, h], orientation);
}
doc.addImage(imgData, 'PNG', 0, 0, w, h, undefined, 'FAST');
}
const fileName = `课件_${DOC_ID}_${new Date().toISOString().slice(0,10)}.pdf`;
doc.save(fileName);
showStatus(`✅ 下载完成！`, '#27ae60');
} catch (error) {
showStatus('❌ 发生错误', 'red');
console.error(error);
}
}
function handleScroll() {
if (isRunning) return;
const scrollTop = window.scrollY || document.documentElement.scrollTop || document.body.scrollTop;
const clientHeight = window.innerHeight || document.documentElement.clientHeight;
const scrollHeight = document.documentElement.scrollHeight || document.body.scrollHeight;
if (scrollTop + clientHeight >= scrollHeight - SCROLL_THRESHOLD) {
const currentImgCount = document.querySelectorAll("img[src*='/thumb/']").length;
showStatus(`检测到触底 (当前 ${currentImgCount} 张)... 等待加载完毕`, '#e67e22');
if (stabilizeTimer) clearTimeout(stabilizeTimer);
stabilizeTimer = setTimeout(() => {
const finalImgCount = document.querySelectorAll("img[src*='/thumb/']").length;
showStatus(`加载稳定 (共 ${finalImgCount} 张)，准备启动...`, '#27ae60');
startDownloadProcess();
}, STABILIZE_WAIT_MS);
}
}
function init() {
const targetImg = document.querySelector("img[src*='/thumb/']");
if (!targetImg) return;
showStatus('请缓慢滚动至底部以触发下载', '#7f8c8d');
window.addEventListener('scroll', handleScroll);
document.body.addEventListener('scroll', handleScroll);
}
setTimeout(init, 2000);
})();