java实现爬虫爬网站图片 java实现爬虫爬网站图片的实例代码

import java.util.ArrayList; 
import java.util.Collections; 
import java.util.HashSet; 
import java.util.List; 
import java.util.Set; 
public class LinkQueue { 
  // 已访问的 url 集合 
  private static Set<String> visitedUrl = Collections.synchronizedSet(new HashSet<String>()); 
  // 未访问的url 
  private static List<String> unVisitedUrl = Collections.synchronizedList(new ArrayList<String>()); 
  // 未访问的URL出队列 
  public static String unVisitedUrlDeQueue() { 
    if (unVisitedUrl.size() > 0) { 
      String url = unVisitedUrl.remove(0); 
      visitedUrl.add(url); 
      return url; 
    } 
    return null; 
  } 
  // 新的url添加进来的时候进行验证，保证只是添加一次 
  public static void addUnvisitedUrl(String url) { 
    if (url != null && !url.trim().equals("") && !visitedUrl.contains(url) 
        && !unVisitedUrl.contains(url)) 
      unVisitedUrl.add(url); 
  } 
  // 判断未访问的URL队列中是否为空 
  public static boolean unVisitedUrlsEmpty() { 
    return unVisitedUrl.isEmpty(); 
  } 
} 

import java.util.HashSet; 
import java.util.Set; 
import org.htmlparser.Node; 
import org.htmlparser.NodeFilter; 
import org.htmlparser.Parser; 
import org.htmlparser.filters.NodeClassFilter; 
import org.htmlparser.filters.OrFilter; 
import org.htmlparser.tags.LinkTag; 
import org.htmlparser.util.NodeList; 
import org.htmlparser.util.ParserException; 
/** 
 * 过滤http的url，获取可以符合规则的url 
 * @author Administrator 
 * 
 */ 
public class ParserHttpUrl { 
  // 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(url); 
      // 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() { 
        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 linkFilter = new OrFilter(new NodeClassFilter( 
          LinkTag.class), frameFilter); 
      // 得到所有经过过滤的标签 
      NodeList list = parser.extractAllNodesThatMatch(linkFilter); 
      for (int i = 0; i < list.size(); i++) { 
        Node tag = list.elementAt(i); 
        if (tag instanceof LinkTag)// <a> 标签 
        { 
          LinkTag link = (LinkTag) tag; 
          String linkUrl = link.getLink();// url 
          if (filter.accept(linkUrl)) 
            links.add(linkUrl); 
        } else// <frame> 标签 
        { 
          // 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; 
  } 
} 

import java.io.File; 
import java.io.FileOutputStream; 
import java.io.InputStream; 
import java.net.URL; 
import java.net.URLConnection; 
import java.util.ArrayList; 
import java.util.List; 
import java.util.regex.Matcher; 
import java.util.regex.Pattern; 
/*** 
 * java抓取网络图片 
 * 
 * @author swinglife 
 * 
 */ 
public class DownLoadPic { 
  // 编码 
  private static final String ECODING = "UTF-8"; 
  // 获取img标签正则 
  private static final String IMGURL_REG = "<img.*src=(.*?)[^>]*?>"; 
  // 获取src路径的正则 
  private static final String IMGSRC_REG = "http:\"?(.*?)(\"|>|\\s+)"; 
  public static void downloadPic(String url) { 
    // 获得html文本内容 
    String HTML = null; 
    try { 
      HTML = DownLoadPic.getHTML(url); 
    } catch (Exception e) { 
      e.printStackTrace(); 
    } 
    if (null != HTML && !"".equals(HTML)) { 
      // 获取图片标签 
      List<String> imgUrl = DownLoadPic.getImageUrl(HTML); 
      // 获取图片src地址 
      List<String> imgSrc = DownLoadPic.getImageSrc(imgUrl); 
      // 下载图片 
      DownLoadPic.download(imgSrc); 
    } 
  } 
  /*** 
   * 获取HTML内容 
   * 
   * @param url 
   * @return 
   * @throws Exception 
   */ 
  private static String getHTML(String url) throws Exception { 
    URL uri = new URL(url); 
    URLConnection connection = uri.openConnection(); 
    InputStream in = connection.getInputStream(); 
    byte[] buf = new byte[1024]; 
    int length = 0; 
    StringBuffer sb = new StringBuffer(); 
    while ((length = in.read(buf, 0, buf.length)) > 0) { 
      sb.append(new String(buf, ECODING)); 
    } 
    in.close(); 
    return sb.toString(); 
  } 
  /*** 
   * 获取ImageUrl地址 
   * 
   * @param HTML 
   * @return 
   */ 
  private static List<String> getImageUrl(String HTML) { 
    Matcher matcher = Pattern.compile(IMGURL_REG).matcher(HTML); 
    List<String> listImgUrl = new ArrayList<String>(); 
    while (matcher.find()) { 
      listImgUrl.add(matcher.group()); 
    } 
    return listImgUrl; 
  } 
  /*** 
   * 获取ImageSrc地址 
   * 
   * @param listImageUrl 
   * @return 
   */ 
  private static List<String> getImageSrc(List<String> listImageUrl) { 
    List<String> listImgSrc = new ArrayList<String>(); 
    for (String image : listImageUrl) { 
      Matcher matcher = Pattern.compile(IMGSRC_REG).matcher(image); 
      while (matcher.find()) { 
        listImgSrc.add(matcher.group().substring(0, 
            matcher.group().length() - 1)); 
      } 
    } 
    return listImgSrc; 
  } 
  /*** 
   * 下载图片 
   * 
   * @param listImgSrc 
   */ 
  private static void download(List<String> listImgSrc) { 
    for (String url : listImgSrc) { 
      try { 
        String imageName = url.substring(url.lastIndexOf("/") + 1, 
            url.length()); 
        URL uri = new URL(url); 
        InputStream in = uri.openStream(); 
        FileOutputStream fo = new FileOutputStream(new File(imageName)); 
        byte[] buf = new byte[1024]; 
        int length = 0; 
        while ((length = in.read(buf, 0, buf.length)) != -1) { 
          fo.write(buf, 0, length); 
        } 
        in.close(); 
        fo.close(); 
      } catch (Exception e) { 
        e.printStackTrace(); 
      } 
    } 
  } 
} 

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

public class Crawler { 
  /** 
   * 抓取过程 
   * 
   * @return 
   * @param seeds 
   */ 
  public void crawling(String url) { // 定义过滤器 
    Filter filter = new Filter() { 
      public boolean accept(String url) { 
        //这里过滤规则随需要爬的网站的规则进行改变，推荐使用正则实现，本人是爬豆瓣网站 
        if(url.indexOf("douban.com/group/topic") != -1 || url.indexOf("douban.com/group/haixiuzu/discussion?start") != -1 ) 
          return true; 
        else 
          return false; 
      } 
    }; 
    // 初始化 URL 队列 
    LinkQueue.addUnvisitedUrl(url); 
    // 循环条件，待抓取的链接不空 
    while (!LinkQueue.unVisitedUrlsEmpty()) { 
      // 队头URL出队列 
      String visitUrl = (String) LinkQueue.unVisitedUrlDeQueue(); 
      if (visitUrl == null) 
        continue; 
      DownLoadPic.downloadPic(visitUrl); 
      // 提取出下载网页中的 URL 
      Set<String> links = ParserHttpUrl.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) { 
    Crawler crawler = new Crawler(); 
    crawler.crawling("http://www.douban.com/group/haixiuzu/discussion?start=0"); 
  } 
}