一个简单的java网络爬虫,由于时间原因,没有进一步解释.

需要的htmlparser.jar包到官方网上去下.

---------------Spider.java---------------------------

import java.io.BufferedReader; import java.io.InputStreamReader; import java.net.URL; import java.net.URLConnection; import java.util.ArrayList; import java.util.HashMap; import java.util.Iterator; import java.util.List; import org.htmlparser.RemarkNode; import org.htmlparser.StringNode; import org.htmlparser.Node; import org.htmlparser.tags.*; import org.htmlparser.Parser; import org.htmlparser.filters.StringFilter; import org.htmlparser.util.NodeIterator; import org.htmlparser.util.NodeList; import org.htmlparser.util.ParserException; import java.util.Queue; import java.util.LinkedList;

public class Spider implements Runnable {

boolean search_key_words = false;

int count = 0;

int limitsite = 10;

int countsite = 1;

String keyword = "中国";//搜索关键字

Parser parser = new Parser();

// List linklist = new ArrayList();

String startsite = "";//搜索的其实站点

SearchResultBean srb;//保存搜索结果

List resultlist = new ArrayList();//搜索到关键字链接列表

List searchedsite = new ArrayList();//已经被搜索站点列表

Queue linklist = new LinkedList();//需解析的链接列表

HashMap> disallowListCache = new HashMap>();

public Spider(String keyword, String startsite) { this.keyword = keyword; this.startsite = startsite; linklist.add(startsite);

srb = new SearchResultBean();

}

public void run() {

// TODO Auto-generated method stub

search(linklist);

}

public void search(Queue queue) {

String url = "";

while(!queue.isEmpty()){ url = queue.peek().toString();//查找列队

try {

if (!isSearched(searchedsite, url)) {

if (isRobotAllowed(new URL(url)))//检查该链接是否被允许搜索

processHtml(url);

else

System.out.println("this page is disallowed to search");

}

} catch (Exception ex) {

}

queue.remove();

}

}

/**

*解析HTML

* @param url

* @throws ParserException

* @throws Exception

*/

public void processHtml(String url) throws ParserException, Exception { searchedsite.add(url);

count = 0;

System.out.println("searching ... :" + url); parser.setURL(url); parser.setEncoding("GBK"); URLConnection uc = parser.getConnection(); uc.connect(); //uc.getLastModified(); NodeIterator nit = parser.elements();

while (nit.hasMoreNodes()) { Node node = nit.nextNode();

parserNode(node);

}

srb.setKeywords(keyword); srb.setUrl(url); srb.setCount_key_words(count); resultlist.add(srb); System.out.println("count keywords is :" + count); System.out.println("----------------------------------------------");

}

/**

*处理HTML标签

* @param tag

* @throws Exception

*/

public void dealTag(Tag tag) throws Exception {

NodeList list = tag.getChildren(); if (list != null) { NodeIterator it = list.elements(); while (it.hasMoreNodes()) { Node node = it.nextNode();

parserNode(node);

}

}

}

/**

*处理HTML标签结点

* @param node

* @throws Exception

*/

public void parserNode(Node node) throws Exception{

if (node instanceof StringNode) {//判断是否是文本结点

StringNode sNode = (StringNode) node;

StringFilter sf = new StringFilter(keyword,false); search_key_words = sf.accept(sNode);

if (search_key_words) {

count++;

}

// System.out.println("text is :"+sNode.getText().trim());

} else if (node instanceof Tag) {//判断是否是标签库结点

Tag atag = (Tag) node;

if (atag instanceof TitleTag) {//判断是否是标TITLE结点

srb.setTitle(atag.getText());

}

if (atag instanceof LinkTag) {//判断是否是标LINK结点

LinkTag linkatag = (LinkTag) atag;

checkLink(linkatag.getLink(), linklist); // System.out.println("-----------------this is link --------------");

}

dealTag(atag);

} else if (node instanceof RemarkNode) {//判断是否是注释

// System.out.println("this is remark");

}

}

/*

*检查链接是否需要加入列队

*/

public void checkLink(String link, Queue queue) { if (link != null && !link.equals("") && link.indexOf("#") == -1) { if (!link.startsWith("http://") && !link.startsWith("ftp://") && !link.startsWith("www.")) {

link = "file:///" + link;

} else if (link.startsWith("www.")) {

link = "http://" + link;

}

if (queue.isEmpty()) queue.add(link);

else {

String link_end_=link.endsWith("/")?link.substring(0,link.lastIndexOf("/")):(link+"/"); if (!queue.contains(link)&&!queue .contains(link_end_)) { queue.add(link);

}

}

}

}

/**

*检查该链接是否已经被扫描

* @param list

* @param url

* @return

*/

public boolean isSearched(List list, String url) {

String url_end_ = "";

if (url.endsWith("/")) { url_end_ = url.substring(0, url.lastIndexOf("/"));

} else {

url_end_ = url + "/";

}

if (list.size() > 0) { if (list.indexOf(url) != -1 || list.indexOf(url_end_) != -1) {

return true;

}

}

return false;

}

/**

*检查URL是否被允许搜索

* @param urlToCheck

* @return

*/

private boolean isRobotAllowed(URL urlToCheck) {

String host = urlToCheck.getHost().toLowerCase();// 获取给出RUL的主机// System.out.println("主机="+host);

//获取主机不允许搜索的URL缓存

ArrayList disallowList = disallowListCache.get(host);

// 如果还没有缓存,下载并缓存。

if (disallowList == null) {

disallowList = new ArrayList();

try {

URL robotsFileUrl = new URL("http://" + host + "/robots.txt");

BufferedReader reader = new BufferedReader(

new InputStreamReader(robotsFileUrl.openStream()));

// 读robot文件，创建不允许访问的路径列表。

String line;

while ((line = reader.readLine()) != null) { if (line.indexOf("Disallow:") == 0) {// 是否包含"Disallow:" String disallowPath = line.substring("Disallow:" .length());// 获取不允许访问路径

// 检查是否有注释。

int commentIndex = disallowPath.indexOf("#"); if (commentIndex != -1) { disallowPath = disallowPath.substring(0,

commentIndex);//去掉注释

}

disallowPath = disallowPath.trim(); disallowList.add(disallowPath);

}

}

for (Iterator it = disallowList.iterator(); it.hasNext();) { System.out.println("Disallow is :" + it.next());

}

// 缓存此主机不允许访问的路径。

disallowListCache.put(host, disallowList);

} catch (Exception e) {

return true; // web站点根目录下没有robots.txt文件,返回真

}

}

String file = urlToCheck.getFile(); // System.out.println("文件getFile()="+file); for (int i = 0; i < disallowList.size(); i++) { String disallow = disallowList.get(i); if (file.startsWith(disallow)) {

return false;

}

}

return true;

}

public static void main(String[] args) {

Spider ph = new Spider("英超",http://www.microsoft.com);

try {

// ph.processHtml();

Thread search = new Thread(ph);

search.start();//启动线程

} catch (Exception ex) {

}

}

}

--------------------------------------SearchResultBean.java---------------------------------------------------------

public class SearchResultBean {

String url = "";

String title = "";

String keywords = "";

int count_key_words = 0;

public int getCount_key_words() {

return count_key_words;

}

public void setCount_key_words(int count_key_words) {

this.count_key_words = count_key_words;

}

public String getKeywords() {

return keywords;

}

public void setKeywords(String keywords) {

this.keywords = keywords;

}

public String getTitle() {

return title;

}

public void setTitle(String title) {

this.title = title;

}

public String getUrl() {

return url;

}

public void setUrl(String url) {

this.url = url;

}

}