java采集网页数据方法【多线程数据采集之一】

第一步抓取数据。

java采集网页数据。获取html文本节点
有几种办法。
第一种： 采用HttpURLConnection

package com.yjf.util;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpWebUtil {

/**
*网页抓取方法
* @param urlString      要抓取的url地址
* @param charset        网页编码方式
* @param timeout        超时时间
* @return               抓取的网页内容
* @throws IOException   抓取异常
*/
public static String GetWebContent(String urlString, final String charset, int timeout) throws IOException {
if (urlString == null || urlString.length() == 0) {
return "";
}
urlString = (urlString.startsWith("http://") || urlString.startsWith("https://")) ? urlString : ("http://" + urlString).intern();
URL url = new URL(urlString);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setDoOutput(true);
conn.setRequestProperty("Pragma", "no-cache");
conn.setRequestProperty("Cache-Control", "no-cache");

int temp = Integer.parseInt(Math.round(Math.random()*(UserAgent.length-1))+"");
conn.setRequestProperty(
"User-Agent",
UserAgent[temp]);  // 模拟手机系统
conn.setRequestProperty("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");//只接受text/html类型，当然也可以接受图片,pdf,*/*任意，就是tomcat/conf/web里面定义那些
conn.setConnectTimeout(timeout);
try {
if (conn.getResponseCode() != HttpURLConnection.HTTP_OK) {
return "";
}
} catch (Exception e) {
try {
System.out.println(e.getMessage());
} catch (Exception e2) {
e2.printStackTrace();
}
return "";
}
InputStream input = conn.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(input,
charset));
String line = null;
StringBuffer sb = new StringBuffer("");
while ((line = reader.readLine()) != null) {
sb.append(line).append("\r\n");
}
if (reader != null) {
reader.close();
}
if (conn != null) {
conn.disconnect();
}
return sb.toString();
}

public static String[] UserAgent = {
"Mozilla/5.0 (Linux; U; Android 2.2; en-us; Nexus One Build/FRF91) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.2",
"Mozilla/5.0 (iPad; U; CPU OS 3_2_2 like Mac OS X; en-us) AppleWebKit/531.21.10 (KHTML, like Gecko) Version/4.0.4 Mobile/7B500 Safari/531.21.11",
"Mozilla/5.0 (SymbianOS/9.4; Series60/5.0 NokiaN97-1/20.0.019; Profile/MIDP-2.1 Configuration/CLDC-1.1) AppleWebKit/525 (KHTML, like Gecko) BrowserNG/7.1.18121",
"Nokia5700AP23.01/SymbianOS/9.1 Series60/3.0",
"UCWEB7.0.2.37/28/998",
"NOKIA5700/UCWEB7.0.2.37/28/977",
"Openwave/UCWEB7.0.2.37/28/978",
"Mozilla/4.0 (compatible; MSIE 6.0; ) Opera/UCWEB7.0.2.37/28/989"
};

}

第二种：采用jar插件Jsoup.jar

org.jsoup.Jsoup

//站点入口列表
public static List<String> getSiteUrlList1(List<String> list,String listurl){
if(list==null || list.size()<=0){
list = new ArrayList<String>();
}
try {
Document docdata = Jsoup.connect(listurl).timeout(10000).get();
String hb = ".m_book li a";
String page = ".page_list .page_up";
Elements ele = docdata.select(hb);
for (Element el : ele) {
list.add(el.attr("href"));
}
if(docdata.select(page)!=null && docdata.select(page).first()!=null){
String url = "http://www.xxxxx.com/site_map/"+docdata.select(page).first().attr("href");
getSiteUrlList1(list, url);
}
} catch (Exception e) {
e.printStackTrace();
}
return list;
}

第三种：http模拟器

可以请求表单数据和 重定向 http://blog.csdn.net/yjflinchong/article/details/8004706
以上先描述第一步抓取数据。后期加入多线程网络数据采集完整介绍。