java爬虫思路代码实现 java写爬虫程序 _爬虫

用java编写网络爬虫求代码和流程急import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
import java.util.*;
import java.util.regex.*;
import javax.swing.*;
import javax.swing.table.*;//一个Web的爬行者(注：爬行在这里的意思与抓?。?捕获相同)
public class SearchCrawler extends JFrame{
//最大URL保存值
private static final String[] MAX_URLS={"50","100","500","1000"};
//缓存robot禁止爬行列表
private HashMap disallowListCache=new HashMap();
//搜索GUI控件
private JTextField startTextField;
private JComboBox maxComboBox;
private JCheckBox limitCheckBox;
private JTextField logTextField;
private JTextField searchTextField;
private JCheckBox caseCheckBox;
private JButton searchButton;
//搜索状态GUI控件
private JLabel crawlingLabel2;
private JLabel crawledLabel2;
private JLabel toCrawlLabel2;
private JProgressBar progressBar;
private JLabel matchesLabel2;
//搜索匹配项表格列表
private JTable table;
//标记爬行机器是否正在爬行
private boolean crawling;
//写日志匹配文件的引用
private PrintWriter logFileWriter;
//网络爬行者的构造函数
public SearchCrawler(){
//设置应用程序标题栏
setTitle("搜索爬行者");
//设置窗体大小
setSize(600,600);
//处理窗体关闭事件
addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){
actionExit();
}
});
//设置文件菜单
JMenuBar menuBar=new JMenuBar();
JMenu fileMenu=new JMenu("文件");
fileMenu.setMnemonic(KeyEvent.VK_F);
JMenuItem fileExitMenuItem=new JMenuItem("退出",KeyEvent.VK_X);
fileExitMenuItem.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
actionExit();
}
});
fileMenu.add(fileExitMenuItem);
menuBar.add(fileMenu);
setJMenuBar(menuBar);
JAVA怎么弄爬虫　以下是一个使用java实现java爬虫思路代码实现的简单爬虫核心代码：
public void crawl() throws Throwable {
while (continueCrawling()) {
CrawlerUrl url = getNextUrl(); //获取待爬取队列中java爬虫思路代码实现的下一个URL
if (url != null) {
printCrawlInfo();
String content = getContent(url); //获取URL的文本信息
//聚焦爬虫只爬取与主题内容相关的网页java爬虫思路代码实现，这里采用正则匹配简单处理
if (isContentRelevant(content, this.regexpSearchPattern)) {
saveContent(url, content); //保存网页至本地
//获取网页内容中的链接java爬虫思路代码实现，并放入待爬取队列中
Collection urlStrings = extractUrls(content, url);
addUrlsToUrlQueue(url, urlStrings);
} else {
System.out.println(url" is not relevant ignoring ...");
}
//延时防止被对方屏蔽
Thread.sleep(this.delayBetweenUrls);
}
}
closeOutputStream();
}
private CrawlerUrl getNextUrl() throws Throwable {
CrawlerUrl nextUrl = null;
while ((nextUrl == null)(!urlQueue.isEmpty())) {
CrawlerUrl crawlerUrl = this.urlQueue.remove();
//doWeHavePermissionToVisit：是否有权限访问该URLjava爬虫思路代码实现，友好的爬虫会根据网站提供的"Robot.txt"中配置的规则进行爬取
//isUrlAlreadyVisited：URL是否访问过，大型的搜索引擎往往采用BloomFilter进行排重，这里简单使用HashMap
//isDepthAcceptable：是否达到指定的深度上限。爬虫一般采取广度优先的方式。一些网站会构建爬虫陷阱（自动生成一些无效链接使爬虫陷入死循环），采用深度限制加以避免
if (doWeHavePermissionToVisit(crawlerUrl)
(!isUrlAlreadyVisited(crawlerUrl))
isDepthAcceptable(crawlerUrl)) {
nextUrl = crawlerUrl;
// System.out.println("Next url to be visited is "nextUrl);
}
}
return nextUrl;
}
private String getContent(CrawlerUrl url) throws Throwable {
//HttpClient4.1的调用与之前的方式不同
HttpClient client = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(url.getUrlString());
StringBuffer strBuf = new StringBuffer();
HttpResponse response = client.execute(httpGet);
if (HttpStatus.SC_OK == response.getStatusLine().getStatusCode()) {
HttpEntity entity = response.getEntity();
if (entity != null) {
BufferedReader reader = new BufferedReader(
new InputStreamReader(entity.getContent(), "UTF-8"));
String line = null;
if (entity.getContentLength()0) {
strBuf = new StringBuffer((int) entity.getContentLength());
while ((line = reader.readLine()) != null) {
strBuf.append(line);
}
}
}
if (entity != null) {
nsumeContent();
}
}
//将url标记为已访问
markUrlAsVisited(url);
return strBuf.toString();
}
public static boolean isContentRelevant(String content,
Pattern regexpPattern) {
boolean retValue = https://www.04ip.com/post/false;
if (content != null) {
//是否符合正则表达式的条件
Matcher m = regexpPattern.matcher(content.toLowerCase());
retValue = https://www.04ip.com/post/m.find();
}
return retValue;
}
public List extractUrls(String text, CrawlerUrl crawlerUrl) {
Map urlMap = new HashMap();
extractHttpUrls(urlMap, text);
extractRelativeUrls(urlMap, text, crawlerUrl);
return new ArrayList(urlMap.keySet());
}
private void extractHttpUrls(Map urlMap, String text) {
Matcher m = (text);
while (m.find()) {
String url = m.group();
String[] terms = url.split("a href=https://www.04ip.com/"");
for (String term : terms) {
// System.out.println("Term = "term);
if (term.startsWith("http")) {
int index = term.indexOf("\"");
if (index0) {
term = term.substring(0, index);
}
urlMap.put(term, term);
System.out.println("Hyperlink: "term);
}
【java爬虫思路代码实现 java写爬虫程序】}
}
}
private void extractRelativeUrls(Map urlMap, String text,
CrawlerUrl crawlerUrl) {
Matcher m = relativeRegexp.matcher(text);
URL textURL = crawlerUrl.getURL();
String host = textURL.getHost();
while (m.find()) {
String url = m.group();
String[] terms = url.split("a href=https://www.04ip.com/"");
for (String term : terms) {
if (term.startsWith("/")) {
int index = term.indexOf("\"");
if (index0) {
term = term.substring(0, index);
}
String s = //"hostterm;
urlMap.put(s, s);
System.out.println("Relative url: "s);
}
}
}
}
public static void main(String[] args) {
try {
String url = "";
Queue urlQueue = new LinkedList();
String regexp = "java";
urlQueue.add(new CrawlerUrl(url, 0));
NaiveCrawler crawler = new NaiveCrawler(urlQueue, 100, 5, 1000L,
regexp);
// boolean allowCrawl = crawler.areWeAllowedToVisit(url);
// System.out.println("Allowed to crawl: "url" "
// allowCrawl);
crawler.crawl();
} catch (Throwable t) {
System.out.println(t.toString());
t.printStackTrace();
}
}
Java网络爬虫怎么实现？网络爬虫是一个自动提取网页的程序，它为搜索引擎从万维网上下载网页，是搜索引擎的重要组成。\x0d\x0a传统爬虫从一个或若干初始网页的URL开始，获得初始网页上的URL，在抓取网页的过程中，不断从当前页面上抽取新的URL放入队列，直到满足系统的一定停止条件。对于垂直搜索来说，聚焦爬虫，即有针对性地爬取特定主题网页的爬虫，更为适合。\x0d\x0a\x0d\x0a以下是一个使用java实现的简单爬虫核心代码：\x0d\x0apublic void crawl() throws Throwable {\x0d\x0awhile (continueCrawling()) {\x0d\x0aCrawlerUrl url = getNextUrl(); //获取待爬取队列中的下一个URL\x0d\x0aif (url != null) {\x0d\x0aprintCrawlInfo();\x0d\x0aString content = getContent(url); //获取URL的文本信息\x0d\x0a\x0d\x0a//聚焦爬虫只爬取与主题内容相关的网页，这里采用正则匹配简单处理\x0d\x0aif (isContentRelevant(content, this.regexpSearchPattern)) {\x0d\x0asaveContent(url, content); //保存网页至本地\x0d\x0a\x0d\x0a//获取网页内容中的链接，并放入待爬取队列中\x0d\x0aCollection urlStrings = extractUrls(content, url);\x0d\x0aaddUrlsToUrlQueue(url, urlStrings);\x0d\x0a} else {\x0d\x0aSystem.out.println(url" is not relevant ignoring ...");\x0d\x0a}\x0d\x0a\x0d\x0a//延时防止被对方屏蔽\x0d\x0aThread.sleep(this.delayBetweenUrls);\x0d\x0a}\x0d\x0a}\x0d\x0acloseOutputStream();\x0d\x0a}\x0d\x0aprivate CrawlerUrl getNextUrl() throws Throwable {\x0d\x0aCrawlerUrl nextUrl = null;\x0d\x0awhile ((nextUrl == null)(!urlQueue.isEmpty())) {\x0d\x0aCrawlerUrl crawlerUrl = this.urlQueue.remove();\x0d\x0a//doWeHavePermissionToVisit：是否有权限访问该URL，友好的爬虫会根据网站提供的"Robot.txt"中配置的规则进行爬取\x0d\x0a//isUrlAlreadyVisited：URL是否访问过，大型的搜索引擎往往采用BloomFilter进行排重，这里简单使用HashMap\x0d\x0a//isDepthAcceptable：是否达到指定的深度上限。爬虫一般采取广度优先的方式。一些网站会构建爬虫陷阱（自动生成一些无效链接使爬虫陷入死循环），采用深度限制加以避免\x0d\x0aif (doWeHavePermissionToVisit(crawlerUrl)\x0d\x0a(!isUrlAlreadyVisited(crawlerUrl))\x0d\x0aisDepthAcceptable(crawlerUrl)) {\x0d\x0anextUrl = crawlerUrl;\x0d\x0a// System.out.println("Next url to be visited is "nextUrl);\x0d\x0a}\x0d\x0a}\x0d\x0areturn nextUrl;\x0d\x0a}\x0d\x0aprivate String getContent(CrawlerUrl url) throws Throwable {\x0d\x0a//HttpClient4.1的调用与之前的方式不同\x0d\x0aHttpClient client = new DefaultHttpClient();\x0d\x0aHttpGet httpGet = new HttpGet(url.getUrlString());\x0d\x0aStringBuffer strBuf = new StringBuffer();\x0d\x0aHttpResponse response = client.execute(httpGet);\x0d\x0aif (HttpStatus.SC_OK == response.getStatusLine().getStatusCode()) {\x0d\x0aHttpEntity entity = response.getEntity();\x0d\x0aif (entity != null) {\x0d\x0aBufferedReader reader = new BufferedReader(\x0d\x0anew InputStreamReader(entity.getContent(), "UTF-8"));\x0d\x0aString line = null;\x0d\x0aif (entity.getContentLength()0) {\x0d\x0astrBuf = new StringBuffer((int) entity.getContentLength());\x0d\x0awhile ((line = reader.readLine()) != null) {\x0d\x0astrBuf.append(line);\x0d\x0a}\x0d\x0a}\x0d\x0a}\x0d\x0aif (entity != null) {\x0d\x0ansumeContent();\x0d\x0a}\x0d\x0a}\x0d\x0a//将url标记为已访问\x0d\x0amarkUrlAsVisited(url);\x0d\x0areturn strBuf.toString();\x0d\x0a}\x0d\x0apublic static boolean isContentRelevant(String content,\x0d\x0aPattern regexpPattern) {\x0d\x0aboolean retValue = https://www.04ip.com/post/false;/x0d/x0aif (content != null) {/x0d/x0a//是否符合正则表达式的条件/x0d/x0aMatcher m = regexpPattern.matcher(content.toLowerCase());/x0d/x0aretValue = m.find();/x0d/x0a}/x0d/x0areturn retValue;/x0d/x0a}/x0d/x0apublic List extractUrls(String text, CrawlerUrl crawlerUrl) {/x0d/x0aMap urlMap = new HashMap();/x0d/x0aextractHttpUrls(urlMap, text);/x0d/x0aextractRelativeUrls(urlMap, text, crawlerUrl);/x0d/x0areturn new ArrayList(urlMap.keySet());/x0d/x0a}/x0d/x0aprivate void extractHttpUrls(Map urlMap, String text) {/x0d/x0aMatcher m = (text);/x0d/x0awhile (m.find()) {/x0d/x0aString url = m.group();/x0d/x0aString[] terms = url.split("a href=https://www.04ip.com/"");\x0d\x0afor (String term : terms) {\x0d\x0a// System.out.println("Term = "term);\x0d\x0aif (term.startsWith("http")) {\x0d\x0aint index = term.indexOf("\"");\x0d\x0aif (index0) {\x0d\x0aterm = term.substring(0, index);\x0d\x0a}\x0d\x0aurlMap.put(term, term);\x0d\x0aSystem.out.println("Hyperlink: "term);\x0d\x0a}\x0d\x0a}\x0d\x0a}\x0d\x0a}\x0d\x0aprivate void extractRelativeUrls(Map urlMap, String text,\x0d\x0aCrawlerUrl crawlerUrl) {\x0d\x0aMatcher m = relativeRegexp.matcher(text);\x0d\x0aURL textURL = crawlerUrl.getURL();\x0d\x0aString host = textURL.getHost();\x0d\x0awhile (m.find()) {\x0d\x0aString url = m.group();\x0d\x0aString[] terms = url.split("a href=https://www.04ip.com/"");\x0d\x0afor (String term : terms) {\x0d\x0aif (term.startsWith("/")) {\x0d\x0aint index = term.indexOf("\"");\x0d\x0aif (index0) {\x0d\x0aterm = term.substring(0, index);\x0d\x0a}\x0d\x0aString s = //"hostterm;\x0d\x0aurlMap.put(s, s);\x0d\x0aSystem.out.println("Relative url: "s);\x0d\x0a}\x0d\x0a}\x0d\x0a}\x0d\x0a\x0d\x0a}\x0d\x0apublic static void main(String[] args) {\x0d\x0atry {\x0d\x0aString url = "";\x0d\x0aQueue urlQueue = new LinkedList();\x0d\x0aString regexp = "java";\x0d\x0aurlQueue.add(new CrawlerUrl(url, 0));\x0d\x0aNaiveCrawler crawler = new NaiveCrawler(urlQueue, 100, 5, 1000L,\x0d\x0aregexp);\x0d\x0a// boolean allowCrawl = crawler.areWeAllowedToVisit(url);\x0d\x0a// System.out.println("Allowed to crawl: "url" "\x0d\x0a// allowCrawl);\x0d\x0acrawler.crawl();\x0d\x0a} catch (Throwable t) {\x0d\x0aSystem.out.println(t.toString());\x0d\x0at.printStackTrace();\x0d\x0a}\x0d\x0a}
如何java写/实现网络爬虫抓取网页网络爬虫是一个自动提取网页的程序，它为搜索引擎从万维网上下载网页，是搜索引擎的重要组成。传统爬虫从一个或若干初始网页的URL开始，获得初始网页上的URL，在抓取网页的过程中，不断从当前页面上抽取新的URL放入队列，直到满足系统的一定停止条件。
java实现网页源码获取的步骤：
(1)新建URL对象，表示要访问的网址。如：url=new URL("");
(2)建立HTTP连接，返回连接对象urlConnection对象。如：urlConnection = (HttpURLConnection)url.openConnection();
(3)获取相应HTTP 状态码。如responsecode=urlConnection.getResponseCode();
(4)如果HTTP 状态码为200，表示成功。从urlConnection对象获取输入流对象来获取请求的网页源代码。
java爬虫思路代码实现的介绍就聊到这里吧，感谢你花时间阅读本站内容，更多关于java写爬虫程序、java爬虫思路代码实现的信息别忘了在本站进行查找喔。

java爬虫思路代码实现 java写爬虫程序

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