图片上传至/target/upload目录下后，通过ip:port/upload/无法访问

做以下配置即可

@Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        try {
            registry.addResourceHandler("/upload/**","/**")
                    .addResourceLocations("classpath:/static/", "file:"+ ResourceUtils.getFile("classpath:").getParent()+"/upload/");
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }