结构化网页内容抽取方法

2021-05-01 11:30

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标签:代码   ignore   oar   controls   tostring   group   length   ror   value   

  为了从几个网站抽取内容,聚合到一起。我于2012年写了一个程序,从多个网站通过结构化方法抽取内容。然后写入数据库,形成一个网站。

(1)正则表达式抽取

  首先,从数据库中读取内容抽取规则:

ArrayList rbList = ruleDao.QueryAllRule();
 
 表结构如下:
技术图片

 

 配置的抽取规则如下:

技术图片

 

 

 

其次,读取网页内容,并通过起始标签抽取出内容,然后通过正则表达式读取出网址URL、标题和发表时间。
直接上代码如下:
private static void doCrawl(RuleBean rb) {     
        String urlContent = getUrlContent(rb.getCrawlUrl(),rb.getEncode());
        if("error".equalsIgnoreCase(urlContent)){
            return;
        }
        String contentArea = getContentArea(urlContent, rb.getAreaBegin(),
                rb.getAreaEnd());
 
        Pattern pt = Pattern.compile(rb.getRegex());
        Matcher mt = pt.matcher(contentArea);
            

        TitleAndUrlBean tuBean;
        while (mt.find()) {
            tuBean = new TitleAndUrlBean();
            tuBean.setAppName(rb.getAppName());
            tuBean.setInfoArea(rb.getInfoArea());

            String rowContent = mt.group();
            rowContent = rowContent.replaceAll(rb.getRemoveRegex(), "");

            // 获取标题
            Matcher title = Pattern.compile(rb.getTitleRegex()).matcher(
                    rowContent);
            while (title.find()) {
                String s = title.group().replaceAll("||>||\\[.*?\\]|","");
                if(s ==null || s.trim().length()
                    s = "error";
                }
                tuBean.setTitle(s);
                
            }

            // 获取网址
            Matcher myurl = Pattern.compile(rb.getUrlRegex()).matcher(
                    rowContent);
            while (myurl.find()) {
                String u = myurl.group().replaceAll(
                        "href=|\"|>|target=|_blank|title", "");
                u = u.replaceAll("\‘|\\\\", "");
                
                if(u!=null && (u.indexOf("http://")==-1)){
                    tuBean.setUrl(rb.getPrefix() + u);
                }else{
                    tuBean.setUrl(u);
                }            
            }
            if(tuBean.getUrl() ==null){
                tuBean.setUrl("error");
            }

            // 获取时间
            Matcher d = Pattern.compile(rb.getDateRegex()).matcher(rowContent);
            while (d.find()) {
                tuBean.setDeliveryDate(d.group());
            }

            boolean r = TitleAndUrlDAO.Add(tuBean);
            
            if (r){
                log.info("crawl add " + tuBean.getAppName() + "_"
                        + tuBean.getInfoArea()+"_"+tuBean.getTitle());
            
                if(tuBean.getAppName().contains("jww")){
                    Cache cTeach = CacheManager.getCacheInfo("index_teach");
                    if(cTeach!=null){
                        teachList  = (List) cTeach.getValue();
                    }
                    
                    teachList.add(tuBean);
                    if(teachList.size()>5){
                        teachList.remove(0);    
                    }
                    cTeach.setValue(teachList);
                    cTeach.setTimeOut(-1);
                    CacheManager.putCache("index_teach", cTeach);
                } 
            }
        }
        System.out.println("end crawl "+rb.getCrawlUrl());
    }
 
(2) dwr返回内容的抽取
    在当时dwr是比较流行的技术,为了抽取dwr的内容,着实花了一番功夫。
首先通过httpClient获取内容
public static void startCrawl() throws Exception{
        DefaultHttpClient httpclient = new DefaultHttpClient();
        HttpResponse response = null;
        HttpEntity entity = null;
        httpclient.getParams().setParameter(ClientPNames.COOKIE_POLICY,
                CookiePolicy.BROWSER_COMPATIBILITY);
        HttpPost httpost = new HttpPost(
                "http://XXXXXXXXXX/Tzgg.getMhggllList.dwr");
        
        List nvps = new ArrayList();
        
        nvps.add(new BasicNameValuePair("callCount", "1"));
        nvps.add(new BasicNameValuePair("page", "/oa/tzggbmh.do"));
        nvps.add(new BasicNameValuePair("c0-scriptName", "Tzgg"));
        nvps.add(new BasicNameValuePair("c0-methodName", "getMhggllList"));
        nvps.add(new BasicNameValuePair("c0-id", "0"));
        nvps.add(new BasicNameValuePair("c0-e1", "string:0"));
        nvps.add(new BasicNameValuePair("c0-e2", "string:0"));
        
        nvps.add(new BasicNameValuePair("c0-e4", "string:%20%20"));
        nvps.add(new BasicNameValuePair("c0-e5", "string:rsTable"));
        nvps.add(new BasicNameValuePair(
                "c0-param0",
                "Array:[reference:c0-e1,reference:c0-e2,reference:c0-e3,reference:c0-e4,reference:c0-e5]"));
        nvps.add(new BasicNameValuePair("c0-e6", "number:20"));
        nvps.add(new BasicNameValuePair("c0-e7", "number:1"));
        nvps.add(new BasicNameValuePair("c0-param1",
                "Object_Object:{pageSize:reference:c0-e6, currentPage:reference:c0-e7}"));
        nvps.add(new BasicNameValuePair("batchId", "0"));

        int infoArea = 1;
        while(infoArea 
            nvps.add(new BasicNameValuePair("c0-e3", "string:0"+infoArea));

            httpost.setEntity(new UrlEncodedFormEntity(nvps));

            response = httpclient.execute(httpost);
            entity = response.getEntity();
            try {
                String responseString = null;
                if (response.getEntity() != null) {
                    responseString = EntityUtils.toString(response.getEntity());
                    if(1 == infoArea){
                        extractData(responseString,"事务通知");
                        infoArea = 3;
                    }else if(infoArea == 3){
                        extractData(responseString,"公告公示");
                        infoArea = 100;
                    }

                }
            } finally {
                
            }   
        }
        httpclient.getConnectionManager().shutdown();
    }
 
然后通过正则表达式抽取
private static void extractData(String content,String infoArea) throws Exception{
        TitleAndUrlDAO tuDao = new TitleAndUrlDAO();
        TitleAndUrlBean tuBean;

        Pattern pt = Pattern.compile("llcs.*?a>");
        Matcher mt = pt.matcher(content);

        Cache c = new Cache();
        while (mt.find()) {
            tuBean = new TitleAndUrlBean();
            tuBean.setAppName("info_xb");
            tuBean.setInfoArea(infoArea);

            String s2 = mt.group();

            // 获取标题
            Matcher title = Pattern.compile("title.*?>").matcher(s2);
            while (title.find()) {
                String s = title.group().replaceAll("title=|>", "");
                
                tuBean.setTitle(unicodeToString(s));
            }

            // 获取网址
            // Matcher myurl = Pattern.compile("href=.*?>").matcher(mt.group());
            Matcher myurl = Pattern.compile("ID=.*?;").matcher(s2);
            while (myurl.find()) {
                String prefix = "http://XXXXXXXXX/tzggbmh.do?theAction=view&parameter.id=";
                tuBean.setUrl(prefix + myurl.group().replaceAll("ID=|;|\"", ""));
            }

            // 获取时间
            Matcher d = Pattern.compile("[0-9]{4}-[0-9]{2}-[0-9]{1,2}")
                    .matcher(s2);
            while (d.find()) {
                tuBean.setDeliveryDate(d.group());
            }

            boolean r = tuDao.Add(tuBean);
           
            if (r){
                log.info("crawl add " + tuBean.getAppName() + "_"
                        + tuBean.getInfoArea()+"_"+tuBean.getTitle());
                    
                Cache cNotice = CacheManager.getCacheInfo("index_notice");
                if(cNotice!=null){
                xb_noticeList = (List) cNotice.getValue();
                }
                
                xb_noticeList.add(tuBean);
                if(xb_noticeList.size()>5){
                    xb_noticeList.remove(0);
                }
                c.setValue(xb_noticeList);
                c.setTimeOut(-1);
                CacheManager.putCache("index_notice", c);                       
            }
        }
    }

 

 本文使用的抽取方法代码,写于2012年,每次网站结构变化的时候需要重新配置规则。

不知道这么多年过来,是否有智能的方法获取网站这种半结构化数据。

如果有,请留言告知,谢谢!

 

结构化网页内容抽取方法

标签:代码   ignore   oar   controls   tostring   group   length   ror   value   

原文地址:https://www.cnblogs.com/siweihz/p/12146167.html


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