Java爬网页方法

/*
Function name:    myGetHttpFile2
Description:      爬网页用
Input:            URL 例如:http://www.126.com
Output:           字符串,网页的HTML
*/  

public String myGetHttpFile2(String url){
    String authentication=null;
    ArrayList al=new ArrayList();
    String PageURL = url;

                PageURL = url ;
        ArrayList urlCollection=new ArrayList();
        Hashtable ht=new Hashtable();
        //代理，如果要穿过代理将下面注释取消
        //ht=System.getProperties();
        //authentication = "Basic " + new sun.misc.BASE64Encoder().encode("代理的用户:代理的密码".getBytes()); 
        //ht.put("proxySet", "true"); 
        //ht.put("proxyHost", "172.16.20.2"); 
        //ht.put("proxyPort", "80");
    
        String urlSource=PageURL;
        StringBuffer htmlBuffer=new StringBuffer();
        String returnStr=null;        
        int codeStart=0;
        int codeEnd=0;
        int linkCount=0;
        
        String getURL=null;
        String realURL=null;
        String urlText=null;
        int from=0;
        int lenURL=0;
        int firstLink=0;
        int endLink=0;
        boolean isNewsLink=false;
        
        try
        {        
            URL su = new URL (urlSource);
            URLConnection conn = su.openConnection(); 
            //conn.setRequestProperty("Proxy-Authorization", authentication);
            
            InputStream imageSource=new URL(urlSource).openStream();
            int ch;
            while((ch=imageSource.read())>-1)
            {
                htmlBuffer.append((char)ch);
            }
            imageSource.close();
            returnStr= new String(htmlBuffer);
            returnStr=new String(returnStr.getBytes("ISO8859_1"),"GBK");
        }
        catch(Exception e)
        {
        }
        
        if(returnStr!=null){
           return returnStr ;
        }else{
           return "empty" ;
        }
   
}