java爬虫实现

RequestAndResponseTool  类： 主要方法： 发送请求 返回响应 并把 响应 封装成 page 类 ;

package com.etoak.crawl.page;

import org.apache.commons.httpclient.DefaultHttpMethodRetryHandler;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.params.HttpMethodParams;

import java.io.IOException;

public class RequestAndResponseTool {


    public static Page  sendRequstAndGetResponse(String url) {
        Page page = null;
        // 1.生成 HttpClinet 对象并设置参数
        HttpClient httpClient = new HttpClient();
        // 设置 HTTP 连接超时 5s
        httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(5000);
        // 2.生成 GetMethod 对象并设置参数
        GetMethod getMethod = new GetMethod(url);
        // 设置 get 请求超时 5s
        getMethod.getParams().setParameter(HttpMethodParams.SO_TIMEOUT, 5000);
        // 设置请求重试处理
        getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler());
        // 3.执行 HTTP GET 请求
        try {
            int statusCode = httpClient.executeMethod(getMethod);
        // 判断访问的状态码
            if (statusCode != HttpStatus.SC_OK) {
                System.err.println("Method failed: " + getMethod.getStatusLine());
            }
        // 4.处理 HTTP 响应内容
            byte[] responseBody = getMethod.getResponseBody();// 读取为字节 数组
            String contentType = getMethod.getResponseHeader("Content-Type").getValue(); // 得到当前返回类型
            page = new Page(responseBody,url,contentType); //封装成为页面
        } catch (HttpException e) {
        // 发生致命的异常，可能是协议不对或者返回的内容有问题
            System.out.println("Please check your provided http address!");
            e.printStackTrace();
        } catch (IOException e) {
        // 发生网络异常
            e.printStackTrace();
        } finally {
        // 释放连接
            getMethod.releaseConnection();
        }
        return page;
    }
}

package com.etoak.crawl.page;


import com.etoak.crawl.util.CharsetDetector;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;

import java.io.UnsupportedEncodingException;

/*
* page
*   1: 保存获取到的响应的相关内容;
* */
public class Page {

    private byte[] content ;
    private String html ;  //网页源码字符串
    private Document doc  ;//网页Dom文档
    private String charset ;//字符编码
    private String url ;//url路径
    private String contentType ;// 内容类型


    public Page(byte[] content , String url , String contentType){
        this.content = content ;
        this.url = url ;
        this.contentType = contentType ;
    }

    public String getCharset() {
        return charset;
    }
    public String getUrl(){return url ;}
    public String getContentType(){ return contentType ;}
    public byte[] getContent(){ return content ;}

    /**
     * 返回网页的源码字符串
     *
     * @return 网页的源码字符串
     */
    public String getHtml() {
        if (html != null) {
            return html;
        }
        if (content == null) {
            return null;
        }
        if(charset==null){
            charset = CharsetDetector.guessEncoding(content); // 根据内容来猜测 字符编码
        }
        try {
            this.html = new String(content, charset);
            return html;
        } catch (UnsupportedEncodingException ex) {
            ex.printStackTrace();
            return null;
        }
    }

    /*
    *  得到文档
    * */
    public Document getDoc(){
        if (doc != null) {
            return doc;
        }
        try {
            this.doc = Jsoup.parse(getHtml(), url);
            return doc;
        } catch (Exception ex) {
            ex.printStackTrace();
            return null;
        }
    }


}

PageParserTool： 类  主要作用 提供了 根据选择器来选取元素 属性 等方法 ；

package com.etoak.crawl.page;

import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

public class PageParserTool {


    /* 通过选择器来选取页面的 */
    public static Elements select(Page page , String cssSelector) {
        return page.getDoc().select(cssSelector);
    }

    /*
     *  通过css选择器来得到指定元素;
     *
     *  */
    public static Element select(Page page , String cssSelector, int index) {
        Elements eles = select(page , cssSelector);
        int realIndex = index;
        if (index < 0) {
            realIndex = eles.size() + index;
        }
        return eles.get(realIndex);
    }


    /**
     * 获取满足选择器的元素中的链接 选择器cssSelector必须定位到具体的超链接
     * 例如我们想抽取id为content的div中的所有超链接，这里
     * 就要将cssSelector定义为div[id=content] a
     *  放入set 中 防止重复；
     * @param cssSelector
     * @return
     */
    public static  Set<String> getLinks(Page page ,String cssSelector) {
        Set<String> links  = new HashSet<String>() ;
        Elements es = select(page , cssSelector);
        Iterator iterator  = es.iterator();
        while(iterator.hasNext()) {
            Element element = (Element) iterator.next();
            if ( element.hasAttr("href") ) {
                links.add(element.attr("abs:href"));
            }else if( element.hasAttr("src") ){
                links.add(element.attr("abs:src"));
            }
        }
        return links;
    }



    /**
     * 获取网页中满足指定css选择器的所有元素的指定属性的集合
     * 例如通过getAttrs("img[src]","abs:src")可获取网页中所有图片的链接
     * @param cssSelector
     * @param attrName
     * @return
     */
    public static ArrayList<String> getAttrs(Page page , String cssSelector, String attrName) {
        ArrayList<String> result = new ArrayList<String>();
        Elements eles = select(page ,cssSelector);
        for (Element ele : eles) {
            if (ele.hasAttr(attrName)) {
                result.add(ele.attr(attrName));
            }
        }
        return result;
    }
}

LinkFilter  接口： 可以起过滤作用；

package com.etoak.crawl.link;

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

CharsetDetector 类； 获取字符编码

/*
 * Copyright (C) 2014 hu
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
package com.etoak.crawl.util;

import org.mozilla.universalchardet.UniversalDetector;

import java.io.UnsupportedEncodingException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * 字符集自动检测
 *
 * @author hu
 */
public class CharsetDetector {

    //从Nutch借鉴的网页编码检测代码
    private static final int CHUNK_SIZE = 2000;

    private static Pattern metaPattern = Pattern.compile(
            "<meta\\s+([^>]*http-equiv=(\"|')?content-type(\"|')?[^>]*)>",
            Pattern.CASE_INSENSITIVE);
    private static Pattern charsetPattern = Pattern.compile(
            "charset=\\s*([a-z][_\\-0-9a-z]*)", Pattern.CASE_INSENSITIVE);
    private static Pattern charsetPatternHTML5 = Pattern.compile(
            "<meta\\s+charset\\s*=\\s*[\"']?([a-z][_\\-0-9a-z]*)[^>]*>",
            Pattern.CASE_INSENSITIVE);

    //从Nutch借鉴的网页编码检测代码
    private static String guessEncodingByNutch(byte[] content) {
        int length = Math.min(content.length, CHUNK_SIZE);

        String str = "";
        try {
            str = new String(content, "ascii");
        } catch (UnsupportedEncodingException e) {
            return null;
        }

        Matcher metaMatcher = metaPattern.matcher(str);
        String encoding = null;
        if (metaMatcher.find()) {
            Matcher charsetMatcher = charsetPattern.matcher(metaMatcher.group(1));
            if (charsetMatcher.find()) {
                encoding = new String(charsetMatcher.group(1));
            }
        }
        if (encoding == null) {
            metaMatcher = charsetPatternHTML5.matcher(str);
            if (metaMatcher.find()) {
                encoding = new String(metaMatcher.group(1));
            }
        }
        if (encoding == null) {
            if (length >= 3 && content[0] == (byte) 0xEF
                    && content[1] == (byte) 0xBB && content[2] == (byte) 0xBF) {
                encoding = "UTF-8";
            } else if (length >= 2) {
                if (content[0] == (byte) 0xFF && content[1] == (byte) 0xFE) {
                    encoding = "UTF-16LE";
                } else if (content[0] == (byte) 0xFE
                        && content[1] == (byte) 0xFF) {
                    encoding = "UTF-16BE";
                }
            }
        }

        return encoding;
    }

    /**
     * 根据字节数组，猜测可能的字符集，如果检测失败，返回utf-8
     *
     * @param bytes 待检测的字节数组
     * @return 可能的字符集，如果检测失败，返回utf-8
     */
    public static String guessEncodingByMozilla(byte[] bytes) {
        String DEFAULT_ENCODING = "UTF-8";
        UniversalDetector detector = new UniversalDetector(null);
        detector.handleData(bytes, 0, bytes.length);
        detector.dataEnd();
        String encoding = detector.getDetectedCharset();
        detector.reset();
        if (encoding == null) {
            encoding = DEFAULT_ENCODING;
        }
        return encoding;
    }

    /**
     * 根据字节数组，猜测可能的字符集，如果检测失败，返回utf-8
     * @param content 待检测的字节数组
     * @return 可能的字符集，如果检测失败，返回utf-8
     */
    public static String guessEncoding(byte[] content) {
        String encoding;
        try {
            encoding = guessEncodingByNutch(content);
        } catch (Exception ex) {
            return guessEncodingByMozilla(content);
        }

        if (encoding == null) {
            encoding = guessEncodingByMozilla(content);
            return encoding;
        } else {
            return encoding;
        }
    }
}

FileTool  文件下载类：

package com.etoak.crawl.util;



import com.etoak.crawl.page.Page;

import java.io.DataOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

/*  本类主要是 下载那些已经访问过的文件*/
public class FileTool {

    private static String dirPath;


    /**
     * getMethod.getResponseHeader("Content-Type").getValue()
     * 根据 URL 和网页类型生成需要保存的网页的文件名，去除 URL 中的非文件名字符
     */
    private static String getFileNameByUrl(String url, String contentType) {
        //去除 http://
        url = url.substring(7);
        //text/html 类型
        if (contentType.indexOf("html") != -1) {
            url = url.replaceAll("[\\?/:*|<>\"]", "_") + ".html";
            return url;
        }
        //如 application/pdf 类型
        else {
            return url.replaceAll("[\\?/:*|<>\"]", "_") + "." +
                    contentType.substring(contentType.lastIndexOf("/") + 1);
        }
    }

    /*
    *  生成目录
    * */
    private static void mkdir() {
        if (dirPath == null) {
            dirPath = Class.class.getClass().getResource("/").getPath() + "temp\\";
        }
        File fileDir = new File(dirPath);
        if (!fileDir.exists()) {
            fileDir.mkdir();
        }
    }

    /**
     * 保存网页字节数组到本地文件，filePath 为要保存的文件的相对地址
     */

    public static void saveToLocal(Page page) {
        mkdir();
        String fileName =  getFileNameByUrl(page.getUrl(), page.getContentType()) ;
        String filePath = dirPath + fileName ;
        byte[] data = page.getContent();
        try {
            //Files.lines(Paths.get("D:\\jd.txt"), StandardCharsets.UTF_8).forEach(System.out::println);
            DataOutputStream out = new DataOutputStream(new FileOutputStream(new File(filePath)));
            for (int i = 0; i < data.length; i++) {
                out.write(data[i]);
            }
            out.flush();
            out.close();
            System.out.println("文件："+ fileName + "已经被存储在"+ filePath  );
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

RegexRule  正则表达式类；

/*
 * Copyright (C) 2014 hu
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
package com.etoak.crawl.util;


import java.util.ArrayList;
import java.util.regex.Pattern;

/**
 *
 * @author hu
 */
public class RegexRule {
    
    public RegexRule(){
        
    }
    public RegexRule(String rule){
        addRule(rule);
    }
    
    public RegexRule(ArrayList<String> rules){
        for (String rule : rules) {
            addRule(rule);
        }
    }
    
    public boolean isEmpty(){
        return positive.isEmpty();
    }

    private ArrayList<String> positive = new ArrayList<String>();
    private ArrayList<String> negative = new ArrayList<String>();

  
    
    /**
     * 添加一个正则规则 正则规则有两种，正正则和反正则 
     * URL符合正则规则需要满足下面条件： 1.至少能匹配一条正正则 2.不能和任何反正则匹配
     * 正正则示例：+a.*c是一条正正则，正则的内容为a.*c，起始加号表示正正则
     * 反正则示例：-a.*c时一条反正则，正则的内容为a.*c，起始减号表示反正则
     * 如果一个规则的起始字符不为加号且不为减号，则该正则为正正则，正则的内容为自身
     * 例如a.*c是一条正正则，正则的内容为a.*c
     * @param rule 正则规则
     * @return 自身
     */
    public RegexRule addRule(String rule) {
        if (rule.length() == 0) {
            return this;
        }
        char pn = rule.charAt(0);
        String realrule = rule.substring(1);
        if (pn == '+') {
            addPositive(realrule);
        } else if (pn == '-') {
            addNegative(realrule);
        } else {
            addPositive(rule);
        }
        return this;
    }

   
    
    /**
     * 添加一个正正则规则
     * @param positiveregex
     * @return 自身
     */
    public RegexRule addPositive(String positiveregex) {
        positive.add(positiveregex);
        return this;
    }

  
    /**
     * 添加一个反正则规则
     * @param negativeregex
     * @return 自身
     */
    public RegexRule addNegative(String negativeregex) {
        negative.add(negativeregex);
        return this;
    }

   
    /**
     * 判断输入字符串是否符合正则规则
     * @param str 输入的字符串
     * @return 输入字符串是否符合正则规则
     */
    public boolean satisfy(String str) {

        int state = 0;
        for (String nregex : negative) {
            if (Pattern.matches(nregex, str)) {
                return false;
            }
        }

        int count = 0;
        for (String pregex : positive) {
            if (Pattern.matches(pregex, str)) {
                count++;
            }
        }
        if (count == 0) {
            return false;
        } else {
            return true;
        }

    }
}

MyCrawler ：

源码下载链接： https://pan.baidu.com/s/1ge7Nkzx   下载密码：  mz5b

文章主要参考： 1： 自己动手写网络爬虫；
2： https://github.com/CrawlScript/WebCollector  
WebCollector是一个无须配置、便于二次开发的JAVA爬虫框架（内核），它提供精简的的API，只需少量代码即可实现一个功能强大的爬虫。WebCollector-Hadoop是WebCollector的Hadoop版本，支持分布式爬取。