1.目录结构
1.图片不能放到templates中，自己试了显示不出来
2.背景设置
背景的路径和位置很重要，否则显示不出来
结果：
图片没有自适应
我们在body中单独设置
<body style=" background-repeat:no-repeat ;
background-size:100% 100%;
background-attachment: fixed;">
实现效果：
完整显示
参考文章：https://blog.csdn.net/qq_36481052/article/details/79075214
参考文章：https://blog.csdn.net/qq_39985298/article/details/89521277?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522164644173516780261939349%2522%252C%2522scm%2522%253A%252220140713.130102334.pc%255Fall.%2522%257D&request_id=164644173516780261939349&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2allfirst_rank_ecpm_v1~rank_v31_ecpm-2-89521277.pc_search_result_cache&utm_term=springboot+html%E8%83%8C%E6%99%AF%E8%87%AA%E9%80%82%E5%BA%94&spm=1018.2226.3001.4187