java读取网络文件

import java.io.*;
import java.net.*;

public class ReadFile {
    static byte[] SjwGetBuffer(String url) throws IOException { 
    	ByteArrayOutputStream  bos  =  new ByteArrayOutputStream();
    	try{
	        URL sjwurl = null; 
	        HttpURLConnection httpUrl = null; 
	        BufferedInputStream bis = null; 
	        byte[] buf = new byte[1024]; 
	         
	        sjwurl = new URL(url); 
	        httpUrl = (HttpURLConnection) sjwurl.openConnection(); 
	        httpUrl.connect();
	        bis = new BufferedInputStream(httpUrl.getInputStream());
	        if(bis==null)return null;
	        while(true)  { 
	            int bytes_read = bis.read( buf ); 
	            if( bytes_read > 0 ) { 
	                bos.write( buf, 0, bytes_read ); 
	            }else { 
	                break; 
	            } 
	        } ; 
	        bis.close(); 
	        httpUrl.disconnect(); 
    	}catch   (Exception e) {   
    		  System.out.println("err!"); 
    		  return null;
    	}
        return bos.toByteArray(); 
    } 

    public static void main(String[] args) throws Exception {
        byte[] strBuf = SjwGetBuffer("http://www.baidu.com/img/baidu_logo.gif"); 
        FileOutputStream fileStream = new FileOutputStream("E:/baidu.gif"); 
        fileStream.write(strBuf); 
        fileStream.close(); 
        
    }