Spring Security :HTTP Status 403-Invalid CSRF Token 'null' was found on the request parameter '_csrf' or header 'X-CSRF-TOKEN'. 原因:1.Spring Security 4.0之后,引入了CSRF,默认是开启.CSRF默认支持的方法: GET|HEAD|TRACE|OPTIONS,不支持POST. Spring Security 3默认关闭csrf,Spring Sec