网络爬虫java版

java版的网络爬虫基本思路是，先获取网页信息，再根据正则表达式提取网页内容

package xuexi;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;




public class webtest {
 /**
  * 获得urlStr对应的网页的源码内容    
  * @param args
  * @throws IOException
  */
    public static String  getURLContent(String urlStr,String charset){
        StringBuffer sb=new StringBuffer();
        try {
        URL    url = new URL(urlStr);
        BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream(),Charset.forName(charset)));
        String temp="";
        do{
            temp=reader.readLine();
            sb.append(temp);
            //System.out.println(temp);
        }while(temp != null);
        
        }catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return sb.toString();
    }
    
    /**
     * 正则表达式截取字符串
     * @param destStr
     * @param regexStr
     * @return
     */
    //参数：字符窜和正则表达式
    public static List<String> getMatherSubstrs(String destStr,String regexStr){
        List<String> result = new ArrayList<String>();
          Pattern p=Pattern.compile(regexStr);
          Matcher m=p.matcher(destStr);
          while(m.find()){
              result.add(m.group(0));
          }
          return result;
    }
    
    
  public static void main(String[] args) throws IOException {
      String content=getURLContent("https://www.qq.com/","utf-8");
      List<String> list=getMatherSubstrs(content,"href=\"+[\\w./:]+\"");
       for(String a: list){
          System.out.println(a); 
       }
      
  }  
}