一个简单的java网络爬虫(spider)
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<String, ArrayList<String>> disallowListCache = new HashMap<String, ArrayList<String>>();
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<String> disallowList = disallowListCache.get(host);
// 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()));
// 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;
}
}