类使用：实现一个people中有一个sayhi的方法调用功能，代码如下：
type People struct {
//..
}
func (p *People) SayHi() {
fmt.Println("************************* say hi !!")
}
func (this *LoginController) Get() {
p := new(People)
p.SayHi()
this.TplName = "login.html"
}
接口使用：实现上面功能，代码如下：
type People struct {
//..
}
func (p *People) SayHi() {
fmt.Println("************************* say hi !!")
}
type IPeople interface {
SayHi()
}
func (this *LoginController) Get() {
var p IPeople = new(People)
p.SayHi()
this.TplName = "login.html"
}