java 使用流下载文件代码

    public HttpServletResponse download(String path,HttpServletResponse response) {  
        try {  
            // path是指欲下载的文件的路径。  
            File file = new File(path);  
            // 取得文件名。  
            String filename = file.getName();  
            // 取得文件的后缀名。  
            String ext = filename.substring(filename.lastIndexOf(".") + 1).toUpperCase();  
      
            // 以流的形式下载文件。  
            InputStream fis = new BufferedInputStream(new FileInputStream(path));  
            byte[] buffer = new byte[fis.available()];  
            fis.read(buffer);  
            fis.close();  
            // 清空response  
            response.reset();  
            // 设置response的Header  
            response.addHeader("Content-Disposition","attachment;filename=" + new String(filename.getBytes()));  
            response.addHeader("Content-Length","" + file.length());  
            OutputStream toClient = new BufferedOutputStream(response.getOutputStream());  
            response.setContentType("application/octet-stream");  
            toClient.write(buffer);  
            toClient.flush();  
            toClient.close();  
        } catch (IOException ex) {  
            ex.printStackTrace();  
        }  
        return response;  
    }