目录
- 定义
- UML
- 参与者
- 示例
定义：
代理模式给某一个对象提供一个代理对象，并由代理对象控制对原对象的引用。
UML:
参与者：
抽象主题(Subject)角色:
声明了代理主题和真实主题的公共接口,使任何需要真实主题的地方都能用代理主题代替.
具体主题(RealSubject)角色：
实现抽象主题角色的具体对象。
代理主题(Proxy)角色:
含有真实主题的引用,从而可以在任何时候操作真实主题,代理主题功过提供和真实主题相同的接口,使它可以随时代替真实主题.代理主题通过持有真实主题的引用,不但可以控制真实主题的创建或删除,可以在真实主题被调用前进行拦截,或在调用后进行某些操作.
示例：
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using System;
namespace DoFactory.GangOfFour.Proxy.Structural
{
/// <summary>
/// MainApp startup class for Structural
/// Proxy Design Pattern.
/// </summary>
class MainApp
{
/// <summary>
/// Entry point into console application.
/// </summary>
static void Main()
{
// Create proxy and request a service
Proxy proxy =
new Proxy();
proxy.Request();
// Wait for user
Console.ReadKey();
}
}
/// <summary>
/// The 'Subject' abstract class
/// </summary>
abstract class Subject
{
public abstract void Request();
}
/// <summary>
/// The 'RealSubject' class
/// </summary>
class RealSubject : Subject
{
public override void Request()
{
Console.WriteLine("
Called RealSubject.Request()");
}
}
/// <summary>
/// The 'Proxy' class
/// </summary>
class Proxy : Subject
{
private RealSubject _realSubject;
public override void Request()
{
// Use 'lazy initialization'
if (_realSubject ==
null)
{
_realSubject =
new RealSubject();
}
_realSubject.Request();
}
}
}
Output
Called RealSubject.Request()
实际运用：
![]()
using System;
namespace DoFactory.GangOfFour.Proxy.RealWorld
{
/// <summary>
/// MainApp startup class for Real-World
/// Proxy Design Pattern.
/// </summary>
class MainApp
{
/// <summary>
/// Entry point into console application.
/// </summary>
static void Main()
{
// Create math proxy
MathProxy proxy =
new MathProxy();
// Do the math
Console.WriteLine("
4 + 2 = " + proxy.Add(4, 2));
Console.WriteLine("
4 - 2 = " + proxy.Sub(4, 2));
Console.WriteLine("
4 * 2 = " + proxy.Mul(4, 2));
Console.WriteLine("
4 / 2 = " + proxy.Div(4, 2));
// Wait for user
Console.ReadKey();
}
}
/// <summary>
/// The 'Subject interface
/// </summary>
public interface IMath
{
double Add(
double x,
double y);
double Sub(
double x,
double y);
double Mul(
double x,
double y);
double Div(
double x,
double y);
}
/// <summary>
/// The 'RealSubject' class
/// </summary>
class Math : IMath
{
public double Add(
double x,
double y) {
return x + y; }
public double Sub(
double x,
double y) {
return x - y; }
public double Mul(
double x,
double y) {
return x * y; }
public double Div(
double x,
double y) {
return x / y; }
}
/// <summary>
/// The 'Proxy Object' class
/// </summary>
class MathProxy : IMath
{
private Math _math =
new Math();
public double Add(
double x,
double y)
{
return _math.Add(x, y);
}
public double Sub(
double x,
double y)
{
return _math.Sub(x, y);
}
public double Mul(
double x,
double y)
{
return _math.Mul(x, y);
}
public double Div(
double x,
double y)
{
return _math.Div(x, y);
}
}
}
Output
4 + 2 = 6
4 - 2 = 2
4 * 2 = 8
4 / 2 = 2