根据图片URL加载图片到缓存

public BufferedImage loadImgByUrl( String imgUrl){
    //创建httpClient客户端
    CloseableHttpClient httpClient=HttpClients.createDefault();
    //创建httpGet发送请求获取文件
    HttpGet httpGet=new HttpGet(imgUrl);
    //将文件读入到输入流中
    try(CloseableHttpResponse httpResponse=httpClient.execute(httpGet);
        InputStream input=httpResponse.getEntity().getContent()){
        return ImageIO.read(input);
    } catch (Exception e) {
        logger.error("loadImgByUrl加载图片失败");
    }
    return null;
}