访问者模式

封装一些施加于某种数据结构之上的操作

/// <summary>
/// 理财
/// </summary>
public abstract class FinancialManagement
{
    /// <summary>
    /// 存钱
    /// </summary>
    public abstract void SaveMoney();
    //外界注入具体访问者
    public abstract void Accept(Visitor visitor);
}
//抽象访问者 Visitor
public abstract class Visitor
{
    public abstract void Visit(FinancialManagement shape);
    public abstract void Visit(Yeb shape);
    public abstract void Visit(Jj shape);
}
//具体访问者
public sealed class VisitorImp : Visitor
{
    public override void Visit(FinancialManagement shape)
    {
        Console.WriteLine("针对银行的操作！");
    }
    public override void Visit(Yeb shape)
    {
        Console.WriteLine("针对余额宝的操作！");
    }
    public override void Visit(Jj shape)
    {
        Console.WriteLine("针对基金的操作！");
    }
}
public sealed class Bank : FinancialManagement
{
    public override void SaveMoney()
    {
        Console.WriteLine("在银行存钱！");
    }
    public override void Accept(Visitor visitor)
    {
        visitor.Visit(this);
    }
}
public sealed class Yeb : FinancialManagement
{
    public override void SaveMoney()
    {
        Console.WriteLine("在余额宝存钱！");
    }
    public override void Accept(Visitor visitor)
    {
        visitor.Visit(this);
    }
}
public sealed class Jj : FinancialManagement
{
    public override void SaveMoney()
    {
        Console.WriteLine("在基金存钱！");
    }
    public override void Accept(Visitor visitor)
    {
        visitor.Visit(this);
    }
}
//结构对象角色
internal class AppStructure
{
    private readonly Visitor _visitor;
    public AppStructure(Visitor visitor)
    {
        _visitor = visitor;
    }
    public void Process(FinancialManagement shape)
    {
        shape.Accept(_visitor);
    }
}

调用：

Visitor visitor = new VisitorImp();
var app = new AppStructure(visitor);
FinancialManagement financialManagement = new Bank();
financialManagement.SaveMoney();
app.Process(financialManagement);
financialManagement = new Yeb();
financialManagement.SaveMoney();
app.Process(financialManagement);
financialManagement = new Jj();
financialManagement.SaveMoney();
app.Process(financialManagement);

reference

C#设计模式之二十一访问者模式（Visitor Pattern）【行为型】

C#设计模式(22)——访问者模式（Vistor Pattern）