package com.common; //http://127.0.0.1:8080/zz3zcwbwebhome/index.jsp //http://127.0.0.1:8080/zz3zcwbwebhome/reply.jsp import java.util.*; import java.net.*; import java.io.*; import java.util.regex.*; public class SearchCrawler implements Runnable { // error message list 错误信息 ArrayList<String> errorList = new ArrayList<String>(); // search result 搜索到的结果 ArrayList<String> resultList = new ArrayList<String>(); String startUrl;// base URL for searching 开始搜索的起点 String searchString;// searching target String 要搜索的字符串(英文) int maxUrl;// 最大处理的url数 boolean caseSensitive = false; // Case Sensitivity 是否区分大小写 boolean limitHost = false; // limit in host 是否在限制的主机内搜索 HashMap<String, ArrayList<String>> disallowListCache = new HashMap<String, ArrayList<String>>(); public SearchCrawler() { } public SearchCrawler(String startUrl, int maxUrl, String searchString) { this.startUrl = startUrl; this.maxUrl = maxUrl; this.searchString = searchString; } public ArrayList<String> getResultList() { return resultList; } // start crawler thread 启动搜索线程 public void run() { crawl(startUrl, maxUrl, searchString, limitHost, caseSensitive); } // check URL format 检测URL格式 private URL verifyUrl(String url) { // only deal with HTTP URL 只处理HTTP URLs if (!url.toLowerCase().startsWith("http://")) return null; URL verifiedUrl = null; try { verifiedUrl = new URL(url); } catch (Exception e) { return null; } return verifiedUrl; } // check accessing URL 检测robot是否允许访问给出的URL. private boolean isRobotAllowed(URL urlToCheck) { // get host URL 获取给出URL的主机 String host = urlToCheck.getHost().toLowerCase(); // not allow to search URL cache from host 获取主机不允许搜索的URL缓存 ArrayList<String> disallowList = disallowListCache.get(host); // if no cache,download and cache 如果还没有缓存,下载并缓存。 if (disallowList == null) { disallowList = new ArrayList<String>(); try { URL robotsFileUrl = new URL("http://" + host + "/robots.txt"); BufferedReader reader = new BufferedReader(new InputStreamReader(robotsFileUrl.openStream())); // read robot file and create not allow URL list // 读robot文件,创建不允许访问的路径列表。 String line = ""; String disallowPath = ""; while ((line = reader.readLine()) != null) { // exists disallow 是否包含"Disallow: if (line.indexOf("Disallow:") == 0) { // get not allow access URL 获取不允许访问路径 disallowPath = line.substring("Disallow:".length()); // check comments 检查是否有注释。 int commentIndex = disallowPath.indexOf("#"); if (commentIndex != -1) { // get comments disallowPath = disallowPath.substring(0, commentIndex); } disallowPath = disallowPath.trim();// trim blank disallowList.add(disallowPath); } } disallowListCache.put(host, disallowList); } catch (Exception e) { return true; } } String file = urlToCheck.getFile(); for (int i = 0; i < disallowList.size(); i++) { String disallow = disallowList.get(i); if (file.startsWith(disallow)) { return false; } } return true; } // remove www from URL 从URL中去掉"www" private String removeWwwFromUrl(String url) { int index = url.indexOf("://www."); if (index != -1) { return url.substring(0, index + 3) + url.substring(index + 7); } return (url); } // parse page and find link 解析页面并找出链接 private ArrayList<String> retrieveLinks(URL pageUrl, String pageContents, HashSet crawledList, boolean limitHost) { // use regex to match 用正则表达式编译链接的匹配模式。 Pattern p = Pattern.compile("<a\\s+href\\s*=\\s*\"?(.*?)[\"|>]", Pattern.CASE_INSENSITIVE); Matcher m = p.matcher(pageContents); ArrayList<String> linkList = new ArrayList<String>(); while (m.find()) { String link = m.group(1).trim(); if (link.length() < 1) { continue; } // jump to page link 跳过链到本页面内链接。 if (link.charAt(0) == '#') { continue; } if (link.indexOf("mailto:") != -1) { continue; } if (link.toLowerCase().indexOf("javascript") != -1) { continue; } if (link.indexOf("://") == -1) { if (link.charAt(0) == '/') {// deal with absolute path 处理绝对地 link = "http://" + pageUrl.getHost() + ":" + pageUrl.getPort() + link; } else { String file = pageUrl.getFile(); if (file.indexOf('/') == -1) {// deal with relative path // 处理相对地址 link = "http://" + pageUrl.getHost() + ":" + pageUrl.getPort() + "/" + link; } else { String path = file.substring(0, file.lastIndexOf('/') + 1); link = "http://" + pageUrl.getHost() + ":" + pageUrl.getPort() + path + link; } } } int index = link.indexOf('#'); if (index != -1) { link = link.substring(0, index); } link = removeWwwFromUrl(link); URL verifiedLink = verifyUrl(link); if (verifiedLink == null) { continue; } /* * If qualified host, excluding those out condition of the URL * 如果限定主机,排除那些不合条件的URL */ if (limitHost && !pageUrl.getHost().toLowerCase().equals(verifiedLink.getHost().toLowerCase())) { continue; } // jump over those already processing link.跳过那些已经处理的链接. if (crawledList.contains(link)) { continue; } linkList.add(link); } return (linkList); } // Download the content of the Web page search, judgment in the page does // not specify a search string 搜索下载Web页面的内容,判断在该页面内有没有指定的搜索字符串 private boolean searchStringMatches(String pageContents, String searchString, boolean caseSensitive) { String searchContents = pageContents; if (!caseSensitive) {// not case sensitive 如果不区分大小写 searchContents = pageContents.toLowerCase(); } Pattern p = Pattern.compile("[\\s]+"); String[] terms = p.split(searchString); for (int i = 0; i < terms.length; i++) { if (caseSensitive) { if (searchContents.indexOf(terms[i]) == -1) { return false; } } else { if (searchContents.indexOf(terms[i].toLowerCase()) == -1) { return false; } } } return true; } // execute search operation 执行实际的搜索操作 public ArrayList<String> crawl(String startUrl, int maxUrls, String searchString, boolean limithost, boolean caseSensitive) { System.out.println("searchString=" + searchString); HashSet<String> crawledList = new HashSet<String>(); LinkedHashSet<String> toCrawlList = new LinkedHashSet<String>(); if (maxUrls < 1) { errorList.add("Invalid Max URLs value."); System.out.println("Invalid Max URLs value."); } if (searchString.length() < 1) { errorList.add("Missing Search String."); System.out.println("Missing search String"); } if (errorList.size() > 0) { System.out.println("err!!!"); return errorList; } // remove www from URL 从开始URL中移出www startUrl = removeWwwFromUrl(startUrl); toCrawlList.add(startUrl); while (toCrawlList.size() > 0) { if (maxUrls != -1) { if (crawledList.size() == maxUrls) { break; } } // Get URL at bottom of the list. String url = toCrawlList.iterator().next(); // Remove URL from the to crawl list. toCrawlList.remove(url); // Convert string url to URL object. URL verifiedUrl = verifyUrl(url); // Skip URL if robots are not allowed to access it. if (!isRobotAllowed(verifiedUrl)) { continue; } // add deal with URL to crawledList 增加已处理的URL到crawledList crawledList.add(url); String pageContents = downloadPage(verifiedUrl, "gb2312"); if (pageContents != null && pageContents.length() > 0) { // 从页面中获取有效的链接 ArrayList<String> links = retrieveLinks(verifiedUrl, pageContents, crawledList, limitHost); toCrawlList.addAll(links); if (searchStringMatches(pageContents, searchString, caseSensitive)) { resultList.add(url); System.out.println(url); } } } return resultList; } public String downloadPage(URL pageUrl) { try { HttpURLConnection conn = (HttpURLConnection) pageUrl.openConnection(); conn.setDoOutput(true); conn.setUseCaches(false); conn.setRequestMethod("GET"); conn.setRequestProperty("User-agent", "Mozilla/5.0 Chrome/18.0.1025.166 Safari/535.19"); conn.connect(); BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream())); // Read page into buffer. String line; StringBuffer pageBuffer = new StringBuffer(); while ((line = reader.readLine()) != null) { pageBuffer.append(line); } reader.close(); return pageBuffer.toString(); } catch (Exception e) { e.printStackTrace(); } return null; } public String downloadPage(URL pageUrl, String codingPattern) { try { HttpURLConnection conn = (HttpURLConnection) pageUrl.openConnection(); conn.setDoOutput(true); conn.setUseCaches(false); conn.setRequestMethod("GET"); conn.setRequestProperty("User-agent", "Mozilla/5.0 (Linux; Android 4.2.1; Nexus 7 Build/JOP40D) AppleWebKit/535.19 (KHTML, like Gecko) Chrome/18.0.1025.166 Safari/535.19"); conn.connect(); // Open connection to URL for reading. BufferedReader reader = new BufferedReader(new InputStreamReader(pageUrl.openStream(), codingPattern)); // Read page into buffer. String line = ""; StringBuffer pageBuffer = new StringBuffer(); while ((line = reader.readLine()) != null) { pageBuffer.append(line); } reader.close(); return pageBuffer.toString(); } catch (Exception e) { e.printStackTrace(); } return null; } }
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