使用原因

图片存储于内部服务器，但是其中某些特殊图片需要允许外网访问。
采取以下方式：
从内部服务器获取到图片—>图片转base64—>给前端

实际操作

/*** 将url上图片转Base64* @param fileUrl 图片地址* @param ss 图片后缀，如png,jpg等* @throws Exception 异常*/
public static String imageToBase64(String fileUrl,String ss) throws Exception {//打开链接URL url = new URL(fileUrl);HttpURLConnection connection;connection = (HttpURLConnection) url.openConnection();connection.setRequestMethod("GET");connection.setConnectTimeout(3000);InputStream inStream = connection.getInputStream();//得到图片的二进制数据ByteArrayOutputStream outStream = new ByteArrayOutputStream();byte[] buffer = new byte[1024];int len;while ((len = inStream.read(buffer)) != -1) {outStream.write(buffer, 0, len);}//关闭输入流inStream.close();byte[] picData = new byte[0];picData = outStream.toByteArray();if(picData.length == 0){log.error("图片数据大小为0,url地址为{}",fileUrl);}return "data:image/"+ss+";base64,"+Base64.getEncoder().encodeToString(picData);
}