servlet_response下载文件

　　通过response响应头content-disposition，来下载文件，如果文件有中文，就用url编码

        String path = this.getServletContext().getRealPath("/download/妞儿.jpg");
        String fileName = path.substring(path.lastIndexOf("\") + 1);
        //如果fileName是中文名字，那么我就要用URL编码 URLEncoder.encode(s, enc);
        response.setHeader("content-disposition", "attachment;filename=" + URLEncoder.encode(fileName,"UTF-8"));
        InputStream in = new FileInputStream(path);
        OutputStream out =  response.getOutputStream();
        int len;
        byte[] buffer = new byte[1024];
        while((len = in.read(buffer)) > 0){
            out.write(buffer,0,len);
        }
        in.close();