Bridge模式使用“對象間的組合關(guān)系”解耦了抽象和實現(xiàn)之間固有的綁定關(guān)系，使得抽象和實現(xiàn)可以沿著各自的維度來變化。所謂抽象和實現(xiàn)沿著各自緯度的變化，即“子類化”它們。
Bridge模式有時候類似于多繼承方案，但是多繼承方案往往違背單一職責(zé)原則（即一個類只有一個變化的原因），復(fù)用性比較差。Bridge模式是比多繼承方案更好的解決方法。
Bridge模式的應(yīng)用一般在“兩個非常強的變化維度”，有時一個類也有多于兩個的變化維度，這時可以使用Bridge的擴展模式。

cpp

class Messager {
public:
    virtual void Login(string username, string password) = 0;
    virtual void SendMessage(string message) = 0;
    virtual void SendPicture(Image image) = 0;
    virtual void PlaySound() = 0;
    virtual void DrawShape() = 0;
    virtual void WriteText() = 0;
    virtual void Connect() = 0;
    virtual ~Messager() {}
};
//平臺實現(xiàn)
class PCMessagerBase : public Messager {
public:
    virtual void PlaySound() {
        //**********
    }
    virtual void DrawShape() {
        //**********
    }
    virtual void WriteText() {
        //**********
    }
    virtual void Connect() {
        //**********
    }
};
class MobileMessagerBase : public Messager {
public:
    virtual void PlaySound() {
        //==========
    }
    virtual void DrawShape() {
        //==========
    }
    virtual void WriteText() {
        //==========
    }
    virtual void Connect() {
        //==========
    }
};
//業(yè)務(wù)抽象
class PCMessagerLite : public PCMessagerBase {
public:
    virtual void Login(string username, string password) {
        PCMessagerBase::Connect();
        //........
    }
    virtual void SendMessage(string message) {
        PCMessagerBase::WriteText();
        //........
    }
    virtual void SendPicture(Image image) {
        PCMessagerBase::DrawShape();
        //........
    }
};
class PCMessagerPerfect : public PCMessagerBase {
public:
    virtual void Login(string username, string password) {
        PCMessagerBase::PlaySound();
        //********
        PCMessagerBase::Connect();
        //........
    }
    virtual void SendMessage(string message) {
        PCMessagerBase::PlaySound();
        //********
        PCMessagerBase::WriteText();
        //........
    }
    virtual void SendPicture(Image image) {
        PCMessagerBase::PlaySound();
        //********
        PCMessagerBase::DrawShape();
        //........
    }
};
class MobileMessagerLite : public MobileMessagerBase {
public:
    virtual void Login(string username, string password) {
        MobileMessagerBase::Connect();
        //........
    }
    virtual void SendMessage(string message) {
        MobileMessagerBase::WriteText();
        //........
    }
    virtual void SendPicture(Image image) {
        MobileMessagerBase::DrawShape();
        //........
    }
};
class MobileMessagerPerfect : public MobileMessagerBase {
public:
    virtual void Login(string username, string password) {
        MobileMessagerBase::PlaySound();
        //********
        MobileMessagerBase::Connect();
        //........
    }
    virtual void SendMessage(string message) {
        MobileMessagerBase::PlaySound();
        //********
        MobileMessagerBase::WriteText();
        //........
    }
    virtual void SendPicture(Image image) {
        MobileMessagerBase::PlaySound();
        //********
        MobileMessagerBase::DrawShape();
        //........
    }
};
void Process() {
    //編譯時裝配
    Messager* m = new MobileMessagerPerfect();
}

class Messager {
protected:
    MessagerImp* messagerImp;//...
public:
    virtual void Login(string username, string password) = 0;
    virtual void SendMessage(string message) = 0;
    virtual void SendPicture(Image image) = 0;
    virtual ~Messager() {}
};
class MessagerImp {
public:
    virtual void PlaySound() = 0;
    virtual void DrawShape() = 0;
    virtual void WriteText() = 0;
    virtual void Connect() = 0;
    virtual MessagerImp() {}
};
//平臺實現(xiàn) n
class PCMessagerImp : public MessagerImp {
public:
    virtual void PlaySound() {
        //**********
    }
    virtual void DrawShape() {
        //**********
    }
    virtual void WriteText() {
        //**********
    }
    virtual void Connect() {
        //**********
    }
};
class MobileMessagerImp : public MessagerImp {
public:
    virtual void PlaySound() {
        //==========
    }
    virtual void DrawShape() {
        //==========
    }
    virtual void WriteText() {
        //==========
    }
    virtual void Connect() {
        //==========
    }
};
//業(yè)務(wù)抽象 m
//類的數(shù)目：1+n+m
class MessagerLite :public Messager {
public:
    virtual void Login(string username, string password) {
        messagerImp->Connect();
        //........
    }
    virtual void SendMessage(string message) {
        messagerImp->WriteText();
        //........
    }
    virtual void SendPicture(Image image) {
        messagerImp->DrawShape();
        //........
    }
};
class MessagerPerfect :public Messager {
public:
    virtual void Login(string username, string password) {
        messagerImp->PlaySound();
        //********
        messagerImp->Connect();
        //........
    }
    virtual void SendMessage(string message) {
        messagerImp->PlaySound();
        //********
        messagerImp->WriteText();
        //........
    }
    virtual void SendPicture(Image image) {
        messagerImp->PlaySound();
        //********
        messagerImp->DrawShape();
        //........
    }
};
void Process() {
    //運行時裝配
    MessagerImp* mImp = new PCMessagerImp();
    Messager* m = new Messager(mImp);
}