Java 实现网络爬虫框架详细代码-编程学习网

Java 实现网络爬虫框架

最近在做一个搜索相关的项目，需要爬取网络上的一些链接存储到索引库中，虽然有很多开源的强大的爬虫框架，但本着学习的态度，自己写了一个简单的网络爬虫，以便了解其中的原理。今天，就为小伙伴们分享下这个简单的爬虫程序！！

一、每个类的功能介绍

DownloadPage.java的功能是下载此超链接的页面源代码.
FunctionUtils.java 的功能是提供不同的静态方法，包括：页面链接正则表达式匹配,获取URL链接的元素,判断是否创建文件,获取页面的Url并将其转换为规范的Url,截取网页网页源文件的目标内容。
HrefOfPage.java 的功能是获取页面源代码的超链接。
UrlDataHanding.java 的功能是整合各个给类，实现url到获取数据到数据处理类。
UrlQueue.java 的未访问Url队列。
VisitedUrlQueue.java 已访问过的URL队列。

二、每个类的源代码

DownloadPage.java 此类要用到HttpClient组件。


package com.sreach.spider;

import java.io.IOException;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;


public class DownloadPage {

 
 public static String getContentFormUrl(String url) {
  
  HttpClient client = new DefaultHttpClient();
  HttpGet getHttp = new HttpGet(url);

  String content = null;

  HttpResponse response;
  try {
   
   response = client.execute(getHttp);
   HttpEntity entity = response.getEntity();

   VisitedUrlQueue.addElem(url);

   if (entity != null) {
    
    content = EntityUtils.toString(entity);

    
    if (FunctionUtils.isCreateFile(url)
      && FunctionUtils.isHasGoalContent(content) != -1) {
     FunctionUtils.createFile(
       FunctionUtils.getGoalContent(content), url);
    }
   }

  } catch (ClientProtocolException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  } finally {
   client.getConnectionManager().shutdown();
  }

  return content;
 }

}

FunctionUtils.java 此类的方法均为static方法


package com.sreach.spider;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class FunctionUtils {

 
 private static String pat = "http://www\\.oschina\\.net/code/explore/.*/\\w+\\.[a-zA-Z]+";
 private static Pattern pattern = Pattern.compile(pat);

 private static BufferedWriter writer = null;

 
 public static int depth = 0;

 
 public static String[] divUrl(String url) {
  return url.split("/");
 }

 
 public static boolean isCreateFile(String url) {
  Matcher matcher = pattern.matcher(url);

  return matcher.matches();
 }

 
 public static void createFile(String content, String urlPath) {
  
  String[] elems = divUrl(urlPath);
  StringBuffer path = new StringBuffer();

  File file = null;
  for (int i = 1; i < elems.length; i++) {
   if (i != elems.length - 1) {

    path.append(elems[i]);
    path.append(File.separator);
    file = new File("D:" + File.separator + path.toString());

   }

   if (i == elems.length - 1) {
    Pattern pattern = Pattern.compile("\\w+\\.[a-zA-Z]+");
    Matcher matcher = pattern.matcher(elems[i]);
    if ((matcher.matches())) {
     if (!file.exists()) {
      file.mkdirs();
     }
     String[] fileName = elems[i].split("\\.");
     file = new File("D:" + File.separator + path.toString()
       + File.separator + fileName[0] + ".txt");
     try {
      file.createNewFile();
      writer = new BufferedWriter(new OutputStreamWriter(
        new FileOutputStream(file)));
      writer.write(content);
      writer.flush();
      writer.close();
      System.out.println("创建文件成功");
     } catch (IOException e) {
      e.printStackTrace();
     }

    }
   }

  }
 }

 
 public static String getHrefOfInOut(String href) {
  
  String resultHref = null;

  
  if (href.startsWith("http://")) {
   resultHref = href;
  } else {
   
   if (href.startsWith("/")) {
    resultHref = "http://www.oschina.net" + href;
   }
  }

  return resultHref;
 }

 
 public static String getGoalContent(String content) {
  int sign = content.indexOf("<pre class=\"");
  String signContent = content.substring(sign);

  int start = signContent.indexOf(">");
  int end = signContent.indexOf("</pre>");

  return signContent.substring(start + 1, end);
 }

 
 public static int isHasGoalContent(String content) {
  return content.indexOf("<pre class=\"");
 }

}

HrefOfPage.java 此类为获取页面的超链接


package com.sreach.spider;

public class HrefOfPage {
 
 public static void getHrefOfContent(String content) {
  System.out.println("开始");
  String[] contents = content.split("<a href=\"");
  for (int i = 1; i < contents.length; i++) {
   int endHref = contents[i].indexOf("\"");

   String aHref = FunctionUtils.getHrefOfInOut(contents[i].substring(
     0, endHref));

   if (aHref != null) {
    String href = FunctionUtils.getHrefOfInOut(aHref);

    if (!UrlQueue.isContains(href)
      && href.indexOf("/code/explore") != -1
      && !VisitedUrlQueue.isContains(href)) {
     UrlQueue.addElem(href);
    }
   }
  }

  System.out.println(UrlQueue.size() + "--抓取到的连接数");
  System.out.println(VisitedUrlQueue.size() + "--已处理的页面数");

 }

}

UrlDataHanding.java 此类主要是从未访问队列中获取url,下载页面，分析url，保存已访问url等操作，实现Runnable接口


package com.sreach.spider;

public class UrlDataHanding implements Runnable {
 
 public void dataHanding(String url) {
  HrefOfPage.getHrefOfContent(DownloadPage.getContentFormUrl(url));
 }

 public void run() {
  while (!UrlQueue.isEmpty()) {
   dataHanding(UrlQueue.outElem());
  }
 }
}

UrlQueue.java 此类主要是用来存放未访问的URL队列


package com.sreach.spider;

import java.util.LinkedList;

public class UrlQueue {
 
 public static LinkedList<String> urlQueue = new LinkedList<String>();

 
 public static final int MAX_SIZE = 10000;

 public synchronized static void addElem(String url) {
  urlQueue.add(url);
 }

 public synchronized static String outElem() {
  return urlQueue.removeFirst();
 }

 public synchronized static boolean isEmpty() {
  return urlQueue.isEmpty();
 }

 public static int size() {
  return urlQueue.size();
 }

 public static boolean isContains(String url) {
  return urlQueue.contains(url);
 }

}

VisitedUrlQueue.java 主要是保存已访问过的URL，使用HashSet来保存，主要是考虑到每个访问过的URL是不同。HashSet刚好符合这个要求


package com.sreach.spider;

import java.util.HashSet;


public class VisitedUrlQueue {
 public static HashSet<String> visitedUrlQueue = new HashSet<String>();

 public synchronized static void addElem(String url) {
  visitedUrlQueue.add(url);
 }

 public synchronized static boolean isContains(String url) {
  return visitedUrlQueue.contains(url);
 }

 public synchronized static int size() {
  return visitedUrlQueue.size();
 }
}

Test.java 此类为测试类


import java.sql.SQLException;

import com.sreach.spider.UrlDataHanding;
import com.sreach.spider.UrlQueue;

public class Test {
 public static void main(String[] args) throws SQLException {
  String url = "http://www.oschina.net/code/explore/achartengine/client/AndroidManifest.xml";
  String url1 = "http://www.oschina.net/code/explore";
  String url2 = "http://www.oschina.net/code/explore/achartengine";
  String url3 = "http://www.oschina.net/code/explore/achartengine/client";

  UrlQueue.addElem(url);
  UrlQueue.addElem(url1);
  UrlQueue.addElem(url2);
  UrlQueue.addElem(url3);

  UrlDataHanding[] url_Handings = new UrlDataHanding[10];

  for (int i = 0; i < 10; i++) {
   url_Handings[i] = new UrlDataHanding();
   new Thread(url_Handings[i]).start();
  }

 }
}

说明一下：由于我抓取的是针对oschina的，所以里面的url正则表达式不适合其他网站，需要自己修改一下。你也可以写成xml来配置。

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