一个简单的java爬虫

package com.jeecg.util; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.OutputStream; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; import java.util.LinkedHashMap; import java.util.Map; import java.util.regex.Matcher; import java.util.regex.Pattern; import javax.net.ssl.HttpsURLConnection; import javax.net.ssl.SSLContext; import javax.net.ssl.SSLSocketFactory; import javax.net.ssl.TrustManager; public class WebCrawlerDemo { public static void main(String[] args) { WebCrawlerDemo webCrawlerDemo = new WebCrawlerDemo(); webCrawlerDemo.myPrint("https://kyfw.12306.cn/"); }public void myPrint(String baseUrl) { Map<String, Boolean> oldMap = new LinkedHashMap<String, Boolean>(); // 存储链接-是否被遍历 // 键值对 String oldLinkHost = ""; // host Pattern p = Pattern.compile("(https?://)?[^/\\s]*"); // 比如： Matcher m = p.matcher(baseUrl); if (m.find()) { oldLinkHost = m.group(); } oldMap.put(baseUrl, false); oldMap = crawlLinks(oldLinkHost, oldMap); //oldMap = crawlLinks(baseUrl, oldMap); for (Map.Entry<String, Boolean> mapping : oldMap.entrySet()) { System.out.println("链接：" + mapping.getKey()); } } /** * * 抓取一个网站所有可以抓取的网页链接，在思路上使用了广度优先算法 * * 对未遍历过的新链接不断发起GET请求，一直到遍历完整个集合都没能发现新的链接 * 则表示不能发现新的链接了，任务结束 * * @param * oldLinkHost 域名，如： * @param oldMap 待遍历的链接集合 * * * @return 返回所有抓取到的链接集合 * */ private Map<String, Boolean> crawlLinks(String oldLinkHost, Map<String, Boolean> oldMap) { Map<String, Boolean> newMap = new LinkedHashMap<String, Boolean>(); String oldLink = ""; for (Map.Entry<String, Boolean> mapping : oldMap.entrySet()) { System.out.println("link:" + mapping.getKey() + "--------check:" + mapping.getValue()); // 如果没有被遍历过 if (!mapping.getValue()) { oldLink = mapping.getKey(); // 发起GET请求 try { URL url = new URL(oldLink); HttpURLConnection connection = (HttpURLConnection) url.openConnection(); connection.setRequestMethod("GET"); connection.setConnectTimeout(2000); connection.setReadTimeout(2000); if (connection.getResponseCode() == 200) { InputStream inputStream = connection.getInputStream(); BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8")); String line = ""; Pattern pattern = Pattern.compile("<a.*?href=[\"\']?((https?://)?/?[^\"\']+)[\"\']?.*?>(.+)</a>"); Matcher matcher = null; while ((line = reader.readLine()) != null) { matcher = pattern.matcher(line); if (matcher.find()) { String newLink = matcher.group(1).trim(); // 链接 // String title = matcher.group(3).trim(); //标题 // 判断获取到的链接是否以http开头 if (!newLink.startsWith("http")) { if (newLink.startsWith("http://www.likecs.com/")) newLink = oldLinkHost + newLink; else newLink = oldLinkHost + "http://www.likecs.com/" + newLink; } // 去除链接末尾的 / if (newLink.endsWith("http://www.likecs.com/")) newLink = newLink.substring(0, newLink.length() - 1); // 去重，并且丢弃其他网站的链接 if (!oldMap.containsKey(newLink) && !newMap.containsKey(newLink) && newLink.startsWith(oldLinkHost)) { // System.out.println("temp2: " + newLink); newMap.put(newLink, false); } } } } } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } oldMap.put(oldLink, true); } } // 有新链接，继续遍历 if (!newMap.isEmpty()) { oldMap.putAll(newMap); oldMap.putAll(crawlLinks(oldLinkHost, oldMap)); // 由于Map的特性，不会导致出现重复的键值对 } return oldMap; } }