版权声明:每天要问下自己:“昨天的自己与今天的自己有啥区别?” https://blog.csdn.net/u010921682/article/details/82783260
职责链模式(Chain Of Responsibility)
使多个对象都有机会处理请求,从而避免请求的发送者和接收者之间的耦合关系。将这个对象连成一条链,并沿着这条链传递该请求,直到有一个对象处理它为止。
UML
代码
abstract class Handler
{
protected Handler successor;
public void SetSuccessor(Handler successor)
{
this.successor = successor;
}
public abstract void HandleRequest(int request);
}
class ConcreteHandler1 : Handler
{
public override void HandleRequest(int request)
{
if (request >= 0 && request < 10)
{
Console.WriteLine("{0} 处理请求 {1}",
this.GetType().Name, request);
}else if (successor != null)
{
successor.HandleRequest(request);
}
}
}
class ConcreteHandler2 : Handler
{
public override void HandleRequest(int request)
{
if (request >= 10 && request < 20)
{
Console.WriteLine("{0} 处理请求 {1}",
this.GetType().Name, request);
}
else if (successor != null)
{
successor.HandleRequest(request);
}
}
}
class ConcreteHandler3 : Handler
{
public override void HandleRequest(int request)
{
if (request >= 20 && request < 30)
{
Console.WriteLine("{0} 处理请求 {1}",
this.GetType().Name, request);
}
else if (successor != null)
{
successor.HandleRequest(request);
}
}
}
// test
Handler h1 = new ConcreteHandler1();
Handler h2 = new ConcreteHandler2();
Handler h3 = new ConcreteHandler3();
h1.SetSuccessor(h2);
h2.SetSuccessor(h3);
int[] requests = { 2, 5, 14, 22, 18, 3, 27, 20};
foreach (int request in requests)
{
h1.HandleRequest(request);
}
// result
ConcreteHandler1 处理请求 2
ConcreteHandler1 处理请求 5
ConcreteHandler2 处理请求 14
ConcreteHandler3 处理请求 22
ConcreteHandler2 处理请求 18
ConcreteHandler1 处理请求 3
ConcreteHandler3 处理请求 27
ConcreteHandler3 处理请求 20
优点
当客户提交一个请求时,请求是沿链传递直至有一个ConcreteHandler对象负责处理它。
接收者和发送者都没有对方的明确信息,且链中的对象自己也并不知道链的结构。结果是职责链可简化对象的相互连接,它们仅需要保持一个指向其后继者的引用,而不需保持它所有的候选接受者的引用。