設計模式 - 攔截過濾器模式
攔截過濾器模式(Intercepting Filter Pattern)用於對應用程序的請求或響應做一些預處理/後處理。定義過濾器,並在把請求傳給實際目標應用程序之前應用在請求上。過濾器可以做認證/授權/記錄日誌,或者跟蹤請求,然後把請求傳給相應的處理程序。以下是這種設計模式的實體。
- 過濾器(Filter) - 過濾器在請求處理程序執行請求之前或之後,執行某些任務。
- 過濾器鏈(Filter Chain) - 過濾器鏈帶有多個過濾器,並在 Target 上按照定義的順序執行這些過濾器。
- Target - Target 對象是請求處理程序。
- 過濾管理器(Filter Manager) - 過濾管理器管理過濾器和過濾器鏈。
- 客戶端(Client) - Client 是向 Target 對象發送請求的對象。
package main import "fmt" type Filter interface { Execute(string) } type AuthenticationFilter struct{} func (a *AuthenticationFilter) Execute(request string) { fmt.Println("AuthenticationFilter request: ", request) } type DebugFilter struct{} func (d *DebugFilter) Execute(request string) { fmt.Println("DebugFilter request: ", request) } type Target struct{} func (t *Target) Execute(request string) { fmt.Println("Executing request: ", request) } type FilterChain struct { Filters []Filter Target *Target } func (f *FilterChain) AddFilter(filter Filter) { f.Filters = append(f.Filters, filter) } func (f *FilterChain) Execute(request string) { for _, f := range f.Filters { f.Execute(request) } f.Target.Execute(request) } func (f *FilterChain) SetTarget(target *Target) { f.Target = target } type FilterManager struct { FilterChain *FilterChain } func NewFilterManager(target *Target) *FilterManager { return &FilterManager{ FilterChain: &FilterChain{ Filters: []Filter{}, Target: target, }, } } func (f *FilterManager) SetFilter(filter Filter) { f.FilterChain.AddFilter(filter) } func (f *FilterManager) FilterRequest(request string) { f.FilterChain.Execute(request) } type Client struct { FilterManager *FilterManager } func (c *Client) SetFilterManager(manager *FilterManager) { c.FilterManager = manager } func (c *Client) SendRequest(request string) { c.FilterManager.FilterRequest(request) } func main() { manager := NewFilterManager(&Target{}) manager.SetFilter(&AuthenticationFilter{}) manager.SetFilter(&DebugFilter{}) client := &Client{FilterManager: manager} client.SendRequest("home") }