利用httpclient＋jericho多线程实现抓取网页内容

 任务描述：
某图书网站按条件查询得出一页20条记录，每条记录有书目的简要信息和url链接到书的详细信息。
需要抓取网站图书的详细信息，保存到本地数据库中。

任务分析：
用httpclient模拟执行url将网站的信息取回，再用jericho包，分析页面元素，将需要的信息取出，保存到数据库中。
因为数据量比较大，还是采用多线程的方式来执行抓取详细页面，分析获得数据。

处理过程：
按条件查询到图书列表信息后，主线程不停的下翻页面，分析每本图书的详细url，将url保存到一个ArrayList中，启多个子线程分别去抓取详细页面的信息。然后利用jericho包分析页面数据并保存到数据库中。

  

代码实现截取如下：
 ......

public class BookCatcher
{
    private static ArrayList threads= new ArrayList();//存储未处理URL
    public static boolean isFinished=false;
   
  public String getUrl() {
   try {
    synchronized (threads) {
     if (threads.size() > 0) {
      String tmp = String.valueOf(threads.get(0));
      threads.remove(0);
      return tmp;
     } else
      return null;
    }
   } catch (Exception e) {
    return null;
   }
  }
    public void process(){
        //处理预处理
       //下面开10个线程等待处理
     new Thread(new Processer(this)).start();
     new Thread(new Processer(this)).start();
     new Thread(new Processer(this)).start();
     new Thread(new Processer(this)).start();
     new Thread(new Processer(this)).start();
     new Thread(new Processer(this)).start();
     new Thread(new Processer(this)).start();
     new Thread(new Processer(this)).start();
     new Thread(new Processer(this)).start();
     new Thread(new Processer(this)).start();

      
     ....   
     for(int j=0;j<pages;j++)//从第一页翻到最后一页
     {
    ...
    source = CommonUtil.getSourceByUrl(url);
    List<Element> elements = source.getAllElementsByClass("ProductTitle");  
    for (Element element : elements){ 
     String href = element.getContent().getFirstStartTag().getAttributeValue("href");  
      
     if (href!=null && !"".equals(href)){  
       synchronized (threads) {
        threads.add(bookurl);// 把URL存进去     
       }    
     } 

     }
     isFinished=true; //主线程处理完所有的url
}

class Processer implements Runnable
{
    BookCatcher c;
    public Processer(BookCatcher c)
    {
        this.c = c;
    }
    public void run()
    {
        String bookUrl = null;
        while((bookUrl=c.getUrl())!=null || !BookCatcher.isFinished)  //当还有记录时就处理       
        {
            if(bookUrl!=null)
            {
          //处理分析页面数据并将数据保存到数据库
              
       Source source = CommonUtil.getSourceByUrl(bookUrl);
       String tmp = "";
   
       BookBean bean = new BookBean();
       bean.setStoreBookUrl(bookUrl);
       
       //书名
       StartTag tag = source.getFirstStartTagByClass("BookTitle");
       tmp = tag.getRenderer().toString();
       bean.setName(tmp);
  
       //作者
       tag = source.getFirstStartTagByClass("bookAuthor");
       if (tag!=null){
        List<StartTag> list = tag.getElement().getAllStartTags(HTMLElementName.A);
        if (list.size()>0)
         bean.setAuthor(list.get(0).getElement().getContent().toString());
       }
       
       //书籍图片
       tag = source.getFirstStartTag("id", "BookImage", false);
       if (tag!=null)
        bean.setPicUrl(tag.getAttributeValue("src").trim());
       
       StartTag tagLeft = source.getFirstStartTagByClass("Left");
       tmp=tagLeft.getRenderer().toString();
       List<String> resList = new ArrayList<String>();
       String[] leftArray = tmp.split("·");
       for (String str:leftArray){      
        if ("".equals(str)) continue;
        resList.add(str);      
       }
       StartTag tagRight = source.getFirstStartTagByClass("Right");
       tmp = tagRight.getRenderer().toString();     
       String[] rightArray = tmp.split("·");
       for (String str:rightArray){
        if ("".equals(str)) continue;
        resList.add(str);      
       }     
       for (String str:resList){
        try{
         String name = CommonUtil.getString(str.split("：")[0]);
         String value = CommonUtil.getString(str.split("：")[1]);
          if ("ISBN".equals(name)) bean.setIsbn(value);   
         if ("出版社".equals(name)) bean.setPublisherOrg(value);
         if ("页码".equals(name)) bean.setPageNum(value);
         if ("出版日期".equals(name)) bean.setPublishDate(value);      
                  
         if ("装帧".equals(name)) bean.setWrapType(value);
         if ("开本".equals(name)) bean.setFormat(value);
        }catch(ArrayIndexOutOfBoundsException ee){}
       }
       
            
       //定价
       tag = source.getFirstStartTagByClass("BookPrice");
       String price = tag.getElement().getAllStartTags(HTMLElementName.STRIKE).get(0).getRenderer().toString();
       price = price.substring(1,price.length());
       bean.setPrice(price);
       
       //零售价格
       tag = source.getFirstStartTagByClass("DetailPrice");
       if (tag!=null)
        bean.setStorePrice(tag.getElement().getAllStartTagsByClass("OurPrice").get(0).getRenderer().toString());
       else
        bean.setStorePrice("0");
               
       List<StartTag> tagList = source.getAllStartTagsByClass("ContentValue");
       if(tagList!=null && tagList.size()>1){
        // 内容简介
        tag = tagList.get(0);
        tmp = tag.getRenderer().toString().trim();
        if(tmp.length()>2000)
         tmp = tmp.substring(0, 1990)+"...";
        bean.setContent(tmp);
  
       }
       new BookBO().saveBook(bean);
          
          
            }else//如果没标志处理则休眠一秒再重新开始处理
            {
                try
                {
                    Thread.sleep(1000);
                } catch (InterruptedException e)
                {
                    e.printStackTrace();
                }
            }
        }
       
    }
}

//CommonUtil中的方法，通过httpclient提交到url，返回的页面信息装入jericho的source
 public static Source getSourceByUrl(final String url) {
  Source source = null;
  HttpClient httpClient = new HttpClient();
  GetMethod getMethod = new GetMethod(url);
  getMethod.getParams().setCookiePolicy(CookiePolicy.BROWSER_COMPATIBILITY);

  getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,
    new DefaultHttpMethodRetryHandler());
  try {
   int statusCode = httpClient.executeMethod(getMethod);
   if (statusCode != HttpStatus.SC_OK) {
    log.error("Method failed: " + getMethod.getStatusLine());
   }

   source = new Source(getMethod.getResponseBodyAsStream());
  } catch (HttpException e) {
   log.error("Please check your provided http address!");
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  } finally {
   getMethod.releaseConnection();
  }
  return source;
 }

 关键字: httpclient, jericho, 多线程