替代if几种写法 1.Optional类 Optional.of("123").ifPresent(e -> { // 不为空的话则执行下面代码 }); // 返回布尔值 Optional<Object> o = Optional.ofNullable(null); boolean present = o.
解决跨域问题 1.nginx反向代理 1.1修改nginx配置 nginx.conf worker_processes 1; events { worker_connections 1024; } http { include mime.types; defau
