一切皆可抽象

public static byte[] getBytes(InputStream is)
    throws Exception
    {
        byte[] data = null;
       
        Collection chunks = new ArrayList();
        byte[] buffer = new byte[1024*1000];
        int read = -1;
        int size = 0;
       
        while((read=is.read(buffer))!=-1)
        {
            if(read>0)
            {
                byte[] chunk = new byte[read];
                System.arraycopy(buffer,0,chunk,0,read);
                chunks.add(chunk);
                size += chunk.length;
            }
        }      
       
        if(size>0)
        {
            ByteArrayOutputStream bos = null;
            try
            {
                bos = new ByteArrayOutputStream(size);
                for(Iterator itr=chunks.iterator();itr.hasNext();)
                {
                    byte[] chunk = (byte[])itr.next();
                    bos.write(chunk);
                }
                data = bos.toByteArray();
            }
            finally
            {
                if(bos!=null)
                {
                    bos.close();
                }
            }
        }
        return data;
    }