版权声明：本文为CSDN博主「霏霏小雨」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/yancr/article/details/102753681

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;

public class ElementUI {

// static String fileP = "C:\\Users\\ChuanruiYan\\Desktop\\element-ui\\"; // 不要从资源管理器复制，有的字符会有问题，导致无法创建文件
static String fileP = "D:\\log\\eui\\"; // 不要从资源管理器复制，有的字符会有问题，导致无法创建文件
static String urlP = "https://unpkg.com/browse/element-ui@2.15.8/";
static String urlF = "https://unpkg.com/element-ui@2.15.8/";
public static void main(String[] args){
    try {
        GetPage("");
    } catch (Exception e) {
        e.printStackTrace();
    }
}
static void GetPage(String after) throws Exception {
    System.out.println(urlP + after);
    new File(fileP + after).mkdir();
    HttpURLConnection http = (HttpURLConnection) (new URL(urlP + after)).openConnection();
    http.setRequestMethod("GET");
    http.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3562.0 Safari/537.36");
    http.connect();
    if(http.getResponseCode() == 200) {
        InputStream inputStream = http.getInputStream();
        byte [] buffer = new byte[1024];
        ArrayList<byte []> byteList = new ArrayList<>();
        ArrayList<Integer> byteLength = new ArrayList<>();
        int length;
        int totalLength = 0;
        while( (length = inputStream.read(buffer)) != -1 ) {
            byteList.add(buffer);
            byteLength.add(length);
            totalLength += length;
            buffer = new byte[1024];
        }
        http.disconnect();
        byte [] all;
        all = new byte[totalLength];
        totalLength = 0;
        while(byteList.size() != 0) {
            System.arraycopy(byteList.get(0), 0, all, totalLength, byteLength.get(0));
            totalLength += byteLength.get(0);
            byteList.remove(0);
            byteLength.remove(0);
        }
        String content = new String(all, StandardCharsets.UTF_8);
        all = null;
        content = content.split("tbody")[1];
        String [] us = content.split("href=\"");
        for(int i = 1; i < us.length; i ++) {
            String href = us[i].split("\"", 2)[0];
            if(href.equals("../")) {
                continue;
            }
            if(href.charAt(href.length() - 1) == '/') {
                GetPage(after + href);
            } else {
                if(!href.equals(".DS_Store"))
                    GetFile(after + href);
            }
        }
    } else {
        GetPage(after);
    }
}
static void GetFile(String url) throws Exception{
    System.out.println(url);
    HttpURLConnection http;
    http = (HttpURLConnection) (new URL(urlF + url)).openConnection();
    http.setRequestMethod("GET");
    http.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3562.0 Safari/537.36");
    http.connect();
    if(http.getResponseCode() == 200) {
        InputStream inputStream = http.getInputStream();
        byte [] buffer = new byte[1024];
        ArrayList<byte []> byteList = new ArrayList<>();
        ArrayList<Integer> byteLength = new ArrayList<>();
        int length;
        int totalLength = 0;
        while( (length = inputStream.read(buffer)) != -1 ) {
            byteList.add(buffer);
            byteLength.add(length);
            totalLength += length;
            buffer = new byte[1024];
        }
        http.disconnect();
        byte [] all;
        all = new byte[totalLength];
        totalLength = 0;
        while(byteList.size() != 0) {
            System.arraycopy(byteList.get(0), 0, all, totalLength, byteLength.get(0));
            totalLength += byteLength.get(0);
            byteList.remove(0);
            byteLength.remove(0);
        }
        File f = new File(fileP + url.replaceAll("/", "\\\\"));
        f.createNewFile();
        FileOutputStream fos = new FileOutputStream(f, false);
        fos.write(all);
        fos.flush();
        fos.close();
    } else {
        GetFile(url);
    }
  }
}