对于一个结构体来说，可以通过同时实现多个接口的方法来实现多个接口，例如：

type Writer interface {
    Write()
}
type Closer interface {
    Close()
}
type WriteCloser struct{}

func (wc *WriteCloser) Write() {
    fmt.Println("write")
}

func (wc *WriteCloser) Close() {
    fmt.Println("close")
}

func main() {
    var It1 Writer = &WriteCloser{}
    It1.Write()
    var It2 Closer = &WriteCloser{}
    It2.Close()
}

运行之后的结果是：

write
close

对于一个接口来说，可以通过接口字段组合实现不同的行为，也叫做接口嵌入。例如：

type Writer interface {
    Write()
}
type WriteCloser struct{
    Writer
}
type writedatabase struct {}
type writefile struct {}
func (wd *writedatabase) Write() {
    fmt.Println("write to database")
}
func (wf *writefile) Write() {
    fmt.Println("write to file")
}
func main() {
    var wc = &WriteCloser {
        &writedatabase{},
    }
    wc.Write()
    var wc2 = &WriteCloser {
        &writefile{},
    }
    wc2.Write()
}

运行之后的结果是：

write to database
write to file