Java版网络爬虫基础（转）

public class LinkQueue {
    // 已访问的 url 集合
    private static Set<String> visitedUrl = new HashSet<String>(); // 待访问的 url 集合 private static Queue<String> unVisitedUrl = new PriorityQueue<String>(); // 获得URL队列 public static Queue<String> getUnVisitedUrl() { return unVisitedUrl; } // 添加到访问过的URL队列中 public static void addVisitedUrl(String url) { visitedUrl.add(url); } // 移除访问过的URL public static void removeVisitedUrl(String url) { visitedUrl.remove(url); } // 未访问的URL出队列 public static Object unVisitedUrlDeQueue() { return unVisitedUrl.poll(); } // 保证每个 url 只被访问一次 public static void addUnvisitedUrl(String url) { if (url != null && !url.trim().equals("") && !visitedUrl.contains(url) && !unVisitedUrl.contains(url)) unVisitedUrl.add(url); } // 获得已经访问的URL数目 public static int getVisitedUrlNum() { return visitedUrl.size(); } // 判断未访问的URL队列中是否为空 public static boolean unVisitedUrlsEmpty() { return unVisitedUrl.isEmpty(); } }

public interface LinkFilter {    
    public boolean accept(String url); }

public class DownLoadFileV4 {

    /* 下载 url 指向的网页 */ public String downloadFile(String url) throws Exception { String filePath = null; // 初始化，此处构造函数就与3.1中不同 HttpClient httpclient = new DefaultHttpClient(); //设置代理和超时，没有使用代理时注掉 HttpHost proxy = new HttpHost("172.16.91.109", 808); httpclient.getParams().setParameter(ConnRoutePNames.DEFAULT_PROXY, proxy); httpclient.getParams().setIntParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, 3000); HttpHost targetHost = new HttpHost(url.replace("http://", "")); HttpGet httpget = new HttpGet("/"); // 查看默认request头部信息 System.out.println("Accept-Charset:" + httpget.getFirstHeader("Accept-Charset")); // 以下这条如果不加会发现无论你设置Accept-Charset为gbk还是utf-8，他都会默认返回gb2312（本例针对google.cn来说） httpget.setHeader("User-Agent", "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.1.2)"); // 用逗号分隔显示可以同时接受多种编码 httpget.setHeader("Accept-Language", "zh-cn,zh;q=0.5"); httpget.setHeader("Accept-Charset", "GB2312,utf-8;q=0.7,*;q=0.7"); // 验证头部信息设置生效 System.out.println("Accept-Charset:" + httpget.getFirstHeader("Accept-Charset").getValue()); // Execute HTTP request System.out.println("executing request " + httpget.getURI()); HttpResponse response = null; try { response = httpclient.execute(targetHost, httpget); // HttpResponse response = httpclient.execute(httpget);  System.out.println("----------------------------------------"); System.out.println("Location: " + response.getLastHeader("Location")); System.out.println(response.getStatusLine().getStatusCode()); System.out.println(response.getLastHeader("Content-Type")); System.out.println(response.getLastHeader("Content-Length")); System.out.println("----------------------------------------"); // 判断页面返回状态判断是否进行转向抓取新链接 int statusCode = response.getStatusLine().getStatusCode(); if ((statusCode == HttpStatus.SC_MOVED_PERMANENTLY) || (statusCode == HttpStatus.SC_MOVED_TEMPORARILY) || (statusCode == HttpStatus.SC_SEE_OTHER) || (statusCode == HttpStatus.SC_TEMPORARY_REDIRECT)) { // 此处重定向处理 此处还未验证 String newUri = response.getLastHeader("Location").getValue(); httpclient = new DefaultHttpClient(); httpget = new HttpGet(newUri); response = httpclient.execute(httpget); } // Get hold of the response entity HttpEntity entity = response.getEntity(); // 查看所有返回头部信息 Header headers[] = response.getAllHeaders(); int ii = 0; while (ii < headers.length) { System.out.println(headers[ii].getName() + ": " + headers[ii].getValue()); ++ii; } // If the response does not enclose an entity, there is no need // to bother about connection release if (entity != null) { // 将源码流保存在一个byte数组当中，因为可能需要两次用到该流， byte[] bytes = EntityUtils.toByteArray(entity); if(response.getLastHeader("Content-Type") != null){ filePath = "f:\\spider\\" + getFileNameByUrl(url, response.getLastHeader("Content-Type").getValue()); }else{ filePath = "f:\\spider\\" + url.substring(url.lastIndexOf("/"), url.length()); } saveToLocal(bytes, filePath); String charSet = ""; // 如果头部Content-Type中包含了编码信息，那么我们可以直接在此处获取 charSet = EntityUtils.getContentCharSet(entity); System.out.println("In header: " + charSet); // 如果头部中没有，那么我们需要 查看页面源码，这个方法虽然不能说完全正确，因为有些粗糙的网页编码者没有在页面中写头部编码信息 if (charSet == "") { String regEx = "(?=<meta).*?(?<=charset=[\\'|\\\"]?)([[a-z]|[A-Z]|[0-9]|-]*)"; Pattern p = Pattern.compile(regEx, Pattern.CASE_INSENSITIVE); Matcher m = p.matcher(new String(bytes)); // 默认编码转成字符串，因为我们的匹配中无中文，所以串中可能的乱码对我们没有影响 boolean result = m.find(); if (m.groupCount() == 1) { charSet = m.group(1); } else { charSet = ""; } } System.out.println("Last get: " + charSet); // 至此，我们可以将原byte数组按照正常编码专成字符串输出（如果找到了编码的话） //System.out.println("Encoding string is: " + new String(bytes, charSet)); }} catch (Exception e) { e.printStackTrace(); } finally { httpclient.getConnectionManager().shutdown(); httpget.abort(); } return filePath; } /** * 根据 url 和网页类型生成需要保存的网页的文件名 去除掉 url 中非文件名字符 */ public String getFileNameByUrl(String url, String contentType) { // remove http:// url = url.substring(7); // text/html类型 if (contentType.indexOf("html") != -1&& url.indexOf(".jpg")!=-1&& url.indexOf(".gif")!=-1) { url = url.replaceAll("[\\?/:*|<>\"]", "_") + ".html"; return url; } else if(url.indexOf(".jpg")!=-1|| url.indexOf(".gif")!=-1){ url =url; return url; }// 如application/pdf类型 else { return url.replaceAll("[\\?/:*|<>\"]", "_") + "." + contentType.substring(contentType.lastIndexOf("/") + 1); } } /** * 保存网页字节数组到本地文件 filePath 为要保存的文件的相对地址 */ private void saveToLocal(byte[] data, String filePath) { try { DataOutputStream out = new DataOutputStream(new FileOutputStream(new File(filePath))); for (int i = 0; i < data.length; i++) out.write(data[i]); out.flush(); out.close(); } catch (IOException e) { e.printStackTrace(); } } }

public class HtmlParserTool {
    public static List<String>imageURLS = new ArrayList<String>(); // 获取一个网站上的链接,filter 用来过滤链接 public static Set<String> extracLinks(String url, LinkFilter filter) { Set<String> links = new HashSet<String>(); try { Parser parser = new Parser(); // 设置代理，没有代理时注掉 System.getProperties().put("proxySet", "true"); System.getProperties().put("proxyHost", "172.16.91.109"); System.getProperties().put("proxyPort", "808"); Parser.getConnectionManager().setProxyHost("123"); parser.setURL(url); parser.setEncoding("utf-8"); // 设置过滤图片 NodeFilter imgfil = new TagNameFilter("IMG"); // 过滤 <frame >标签的 filter，用来提取 frame 标签里的 src 属性所表示的链接 NodeFilter frameFilter = new NodeFilter() { private static final long serialVersionUID = -6464506837817768182L; public boolean accept(Node node) { if (node.getText().startsWith("frame src=")) { return true; } else { return false; } } }; // OrFilter 来设置过滤 <a> 标签，和 <frame> 标签 OrFilter lf = new OrFilter(new NodeClassFilter(LinkTag.class), frameFilter); // 得到所有经过过滤的标签 //NodeList list = parser.extractAllNodesThatMatch(lf); NodeList list = parser.extractAllNodesThatMatch(imgfil); for (int i = 0; i < list.size(); i++) { Node tag = list.elementAt(i); if (tag instanceof LinkTag)// <a> 标签  { if (tag instanceof ImageTag) { // 加入图片信息 ImageTag link = (ImageTag) tag; String imageUrl = link.getImageURL();// url  links.add(imageUrl); imageURLS.add(imageUrl); System.out.println(imageUrl); }else{ LinkTag link = (LinkTag) tag; String linkUrl = link.getLink();// url if (filter.accept(linkUrl)) links.add(linkUrl); } } else// <frame> 标签  { if (tag instanceof ImageTag) { // 加入图片信息 ImageTag link = (ImageTag) tag; String imageUrl = link.getImageURL();// url  links.add(imageUrl); imageURLS.add(imageUrl); System.out.println(imageUrl); } else { // 提取 frame 里 src 属性的链接如 <frame src="test.html"/> String frame = tag.getText(); int start = frame.indexOf("src="); frame = frame.substring(start); int end = frame.indexOf(" "); if (end == -1) end = frame.indexOf(">"); String frameUrl = frame.substring(5, end - 1); if (filter.accept(frameUrl)) links.add(frameUrl); } } } } catch (ParserException e) { e.printStackTrace(); } return links; } }

public class MyCrawler {
    /**
     * 使用种子初始化 URL 队列
     * 
     * @return * @param seeds * 种子URL */ private void initCrawlerWithSeeds(String[] seeds) { for (int i = 0; i < seeds.length; i++) LinkQueue.addUnvisitedUrl(seeds[i]); } /** * 抓取过程 * * @return * @param seeds * @throws Exception */ public void crawling(String[] seeds) throws Exception { LinkFilter filter = new LinkFilter() { public boolean accept(String url) { if (url.contains("csdn")) return true; else return false; } }; // 初始化 URL 队列  initCrawlerWithSeeds(seeds); // 循环条件：待抓取的链接不空且抓取的网页不多于1000 while (!LinkQueue.unVisitedUrlsEmpty() && LinkQueue.getVisitedUrlNum() <= 1000) { // 队头URL出队列 String visitUrl = (String) LinkQueue.unVisitedUrlDeQueue(); if (visitUrl == null) continue; DownLoadFileV4 downLoader = new DownLoadFileV4(); // 下载网页 try { downLoader.downloadFile(visitUrl); // 只下载图片，不下载网页 //if(HtmlParserTool.imageURLS.contains(visitUrl)){ // downLoader.downloadFile(visitUrl); //} } catch (Exception e) { // TODO Auto-generated catch block  e.printStackTrace(); } System.out.println(); // 该 url 放入到已访问的 URL 中  LinkQueue.addVisitedUrl(visitUrl); // 提取出下载网页中的 URL Set<String> links = HtmlParserTool.extracLinks(visitUrl, filter); // 新的未访问的 URL 入队 for (String link : links) { LinkQueue.addUnvisitedUrl(link); } } } // main 方法入口 public static void main(String[] args) throws Exception { MyCrawler crawler = new MyCrawler(); crawler.crawling(new String[] {"http://www.csdn.com"}); } }


http://www.cnblogs.com/lnlvinso/p/3970865.html