这里的remoteFilePath 为远程文件，可理解为就是一个文件地址（实际可能为返回的文件流）

/** 
     * 获取远程文件 
     * @param remoteFilePath 远程文件路径  
     * @param localFilePath 本地文件路径 
     */
    public void downloadFile(String remoteFilePath, String localFilePath)
    {
        URL urlfile = null;
        HttpURLConnection httpUrl = null;
        BufferedInputStream bis = null;
        BufferedOutputStream bos = null;
       
        String fileName = "mcsetup.exe";
        String ramdom = System.currentTimeMillis() + ""
        + new Random().nextInt(100) + new Random().nextInt(100)
        + new Random().nextInt(100) + getSequence();
        fileName = ramdom + "_" + fileName;
        File f = new File(localFilePath+fileName);
        try
        {
            urlfile = new URL(remoteFilePath);
            httpUrl = (HttpURLConnection)urlfile.openConnection();
            httpUrl.connect();
            bis = new BufferedInputStream(httpUrl.getInputStream());
            bos = new BufferedOutputStream(new FileOutputStream(f));
            int len = 2048;
            byte[] b = new byte[len];
            while ((len = bis.read(b)) != -1)
            {
                bos.write(b, 0, len);
            }
            bos.flush();
            bis.close();
            httpUrl.disconnect();
        }
        catch (Exception e)
        {
           e.printStackTrace();
        }
        finally
        {
            try
            {
                bis.close();
                bos.close();
            }
            catch (IOException e)
            {
               e.printStackTrace();
            }
        }
    }