response 下载文件

        String basePath = "D://test.json";
        String filename = basePath.substring(basePath.lastIndexOf("\\") + 1);  

        response.setHeader("content-disposition", "attachment;filename=" + URLEncoder.encode(filename, "UTF-8"));
        InputStream in = null;
        OutputStream out = null;
        try {
            in = new FileInputStream(basePath);
            int len = 0;
             byte[] buffer = new byte[1024];
             out = response.getOutputStream();
            while((len = in.read(buffer)) > 0) {
                out.write(buffer,0,len);
            }  

        }catch(Exception e) {
            throw new RuntimeException(e);
        }finally {
            if(in != null) {
                try {
                    in.close();
                }catch(Exception e) {
                    throw new RuntimeException(e);
                }  

            }
        }