页面登陆状态——cookies
cookie操作
this.$cookies.set('key',value,过期时间秒)
this.$cookies.get('key')
this.$cookies.remove('key')
前端注销
logout(){
//清除cookie
this.$cookies.remove('token')
this.$cookies.remove('username')
//把两个变量值为空
this.username=''
this.token=''
},