InputStream

网络地址转InputStream

URL url = new URL(FtpConfig.getExcalPath());
InputStream bis = new BufferedInputStream(url.openStream());

内部地址转InputStream

String  filePath = getClass().getResource("/template/studentInfo.xlsx").getPath();
InputStream bis = new BufferedInputStream(new FileInputStream(new File(filePath)));

File文件到InputStream

InputStream inputStream = file.getInputStream();