{"id":104,"date":"2008-03-04T16:21:24","date_gmt":"2008-03-04T16:21:24","guid":{"rendered":""},"modified":"2008-03-04T16:21:24","modified_gmt":"2008-03-04T16:21:24","slug":"104","status":"publish","type":"post","link":"https:\/\/www.poloo.org\/?p=104","title":{"rendered":"\u804c\u8d23\u94fe\u6a21\u5f0f(Chain of Responsibility Pattern)"},"content":{"rendered":"

\u4e00\u3001 \u804c\u8d23\u94fe\uff08Chain of Responsibility\uff09\u6a21\u5f0f
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\u4ece\u51fb\u9f13\u4f20\u82b1\u8c08\u8d77<\/p>\n

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\u4e8c\u3001 \u8d23\u4efb\u94fe\u6a21\u5f0f\u7684\u7ed3\u6784<\/p>\n

\u8d23\u4efb\u94fe\u6a21\u5f0f\u6d89\u53ca\u5230\u7684\u89d2\u8272\u5982\u4e0b\u6240\u793a\uff1a

\u62bd\u8c61\u5904\u7406\u8005(Handler)\u89d2\u8272\uff1a\u5b9a\u4e49\u51fa\u4e00\u4e2a\u5904\u7406\u8bf7\u6c42\u7684\u63a5\u53e3\u3002\u5982\u679c\u9700\u8981\uff0c\u63a5\u53e3\u53ef\u4ee5\u5b9a\u4e49\u51fa\u4e00\u4e2a\u65b9\u6cd5\uff0c\u4ee5\u8bbe\u5b9a\u548c\u8fd4\u56de\u5bf9\u4e0b\u5bb6\u7684\u5f15\u7528\u3002\u8fd9\u4e2a\u89d2\u8272\u901a\u5e38\u7531\u4e00\u4e2a\u62bd\u8c61\u7c7b\u6216\u63a5\u53e3\u5b9e\u73b0\u3002<\/p>\n

\u5177\u4f53\u5904\u7406\u8005(ConcreteHandler)\u89d2\u8272\uff1a\u5177\u4f53\u5904\u7406\u8005\u63a5\u5230\u8bf7\u6c42\u540e\uff0c\u53ef\u4ee5\u9009\u62e9\u5c06\u8bf7\u6c42\u5904\u7406\u6389\uff0c\u6216\u8005\u5c06\u8bf7\u6c42\u4f20\u7ed9\u4e0b\u5bb6\u3002\u7531\u4e8e\u5177\u4f53\u5904\u7406\u8005\u6301\u6709\u5bf9\u4e0b\u5bb6\u7684\u5f15\u7528\uff0c\u56e0\u6b64\uff0c\u5982\u679c\u9700\u8981\uff0c\u5177\u4f53\u5904\u7406\u8005\u53ef\u4ee5\u8bbf\u95ee\u4e0b\u5bb6\u3002<\/p>\n

\u4e09\u3001 \u8d23\u4efb\u94fe\u6a21\u5f0f\u7684\u793a\u610f\u6027\u6e90\u4ee3\u7801

\/\/ Chain of Responsibility pattern -- Structural example  
using System;<\/p>\n

\/\/ \"Handler\"
abstract class Handler
{
  \/\/ Fields
  protected Handler successor;<\/p>\n

  \/\/ Methods
  public void SetSuccessor( Handler successor )
  {
    this.successor = successor;
  }
  abstract public void HandleRequest( int request );
}<\/p>\n

\/\/ \"ConcreteHandler1\"
class ConcreteHandler1 : Handler
{
  \/\/ Methods
  override public void HandleRequest( int request )
  {
    if( request >= 0 && request < 10 )
      Console.WriteLine(\"{0} handled request {1}\",
        this, request );
    else
      if( successor != null )
      successor.HandleRequest( request );
  }
}<\/p>\n

\/\/ \"ConcreteHandler2\"
class ConcreteHandler2 : Handler
{
  \/\/ Methods
  override public void HandleRequest( int request )
  {
    if( request >= 10 && request < 20 )
      Console.WriteLine(\"{0} handled request {1}\",
        this, request );
    else
      if( successor != null )
      successor.HandleRequest( request );
  }
}<\/p>\n

\/\/ \"ConcreteHandler3\"
class ConcreteHandler3 : Handler
{
  \/\/ Methods
  override public void HandleRequest( int request )
  {
    if( request >= 20 && request < 30 )
      Console.WriteLine(\"{0} handled request {1}\",
        this, request );
    else
      if( successor != null )
      successor.HandleRequest( request );
  }
}<\/p>\n

\/**\/\/\/\/ <summary>
\/\/\/ Client test
\/\/\/ <\/summary>
public class Client
{
  public static void Main( string[] args )
  {
    \/\/ Setup Chain of Responsibility
    Handler h1 = new ConcreteHandler1();
    Handler h2 = new ConcreteHandler2();
    Handler h3 = new ConcreteHandler3();
    h1.SetSuccessor(h2);
    h2.SetSuccessor(h3);<\/p>\n

    \/\/ Generate and process request
    int[] requests = { 2, 5, 14, 22, 18, 3, 27, 20 };<\/p>\n

    foreach( int request in requests )
      h1.HandleRequest( request );<\/p>\n

  }
}
<\/code><\/p>\n

\u56db\u3001 \u7eaf\u7684\u4e0e\u4e0d\u7eaf\u7684\u8d23\u4efb\u94fe\u6a21\u5f0f
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\u5728\u4e00\u4e2a\u7eaf\u7684\u8d23\u4efb\u94fe\u6a21\u5f0f\u91cc\u9762\uff0c\u4e00\u4e2a\u8bf7\u6c42\u5fc5\u987b\u88ab\u67d0\u4e00\u4e2a\u5904\u7406\u8005\u5bf9\u8c61\u6240\u63a5\u6536\uff1b\u5728\u4e00\u4e2a\u4e0d\u7eaf\u7684\u8d23\u4efb\u94fe\u6a21\u5f0f\u91cc\u9762\uff0c\u4e00\u4e2a\u8bf7\u6c42\u53ef\u4ee5\u6700\u7ec8\u4e0d\u88ab\u4efb\u4f55\u63a5\u6536\u7aef\u5bf9\u8c61\u6240\u63a5\u6536\u3002\u7eaf\u7684\u8d23\u4efb\u94fe\u6a21\u5f0f\u7684\u4f8b\u5b50\u662f\u4e0d\u5bb9\u6613\u627e\u5230\u7684\uff0c\u4e00\u822c\u770b\u5230\u7684\u4f8b\u5b50\u5747\u662f\u4e0d\u7eaf\u7684\u8d23\u4efb\u94fe\u6a21\u5f0f\u7684\u5b9e\u73b0\u3002<\/p>\n

\u4e94\u3001 \u8d23\u4efb\u94fe\u6a21\u5f0f\u7684\u5b9e\u9645\u5e94\u7528\u6848\u4f8b
\u4e0b\u9762\u7684\u8d23\u4efb\u94fe\u6a21\u5f0f\u4ee3\u7801\u6f14\u793a\u4e86\u4e0d\u540c\u804c\u52a1\u7684\u4eba\u6839\u636e\u6240\u8bbe\u5b9a\u7684\u6743\u9650\u5bf9\u4e00\u4e2a\u8d2d\u4e70\u8bf7\u6c42\u4f5c\u51fa\u51b3\u7b56\u6216\u5c06\u5176\u4ea4\u7ed9\u66f4\u9ad8\u7684\u51b3\u7b56\u8005\u3002
\/\/ Chain of Responsibility pattern -- Real World example  
using System;<\/p>\n

\/\/ \"Handler\"
abstract class Approver
{
  \/\/ Fields
  protected string name;
  protected Approver successor;<\/p>\n

  \/\/ Constructors
  public Approver( string name )
  {
    this.name = name;
  }<\/p>\n

  \/\/ Methods
  public void SetSuccessor( Approver successor )
  {
    this.successor = successor;
  }<\/p>\n

  abstract public void ProcessRequest( PurchaseRequest request );
}<\/p>\n

\/\/ \"ConcreteHandler\"
class Director : Approver
{
  \/\/ Constructors
  public Director ( string name ) : base( name ) {}<\/p>\n

  \/\/ Methods
  override public void ProcessRequest( PurchaseRequest request )
  {
    if( request.Amount < 10000.0 )
      Console.WriteLine( \"{0} {1} approved request# {2}\",
        this, name, request.Number);
    else
      if( successor != null )
      successor.ProcessRequest( request );
  }
}<\/p>\n

\/\/ \"ConcreteHandler\"
class VicePresident : Approver
{
  \/\/ Constructors
  public VicePresident ( string name ) : base( name ) {}<\/p>\n

  \/\/ Methods
  override public void ProcessRequest( PurchaseRequest request )
  {
    if( request.Amount < 25000.0 )
      Console.WriteLine( \"{0} {1} approved request# {2}\",
        this, name, request.Number);
    else
      if( successor != null )
      successor.ProcessRequest( request );
  }
}<\/p>\n

\/\/ \"ConcreteHandler\"
class President : Approver
{
  \/\/ Constructors
  public President ( string name ) : base( name ) {}
  \/\/ Methods
  override public void ProcessRequest( PurchaseRequest request )
  {
    if( request.Amount < 100000.0 )
      Console.WriteLine( \"{0} {1} approved request# {2}\",
        this, name, request.Number);
    else
      Console.WriteLine( \"Request# {0} requires \" +
        \"an executive meeting!\", request.Number );
  }
}<\/p>\n

\/\/ Request details
class PurchaseRequest
{
  \/\/ Member Fields
  private int number;
  private double amount;
  private string purpose;<\/p>\n

  \/\/ Constructors
  public PurchaseRequest( int number,  
    double amount, string purpose )
  {
    this.number = number;
    this.amount = amount;
    this.purpose = purpose;
  }<\/p>\n

  \/\/ Properties
  public double Amount
  {
    get{ return amount; }
    set{ amount = value; }
  }<\/p>\n

  public string Purpose
  {
    get{ return purpose; }
    set{ purpose = value; }
  }<\/p>\n

  public int Number
  {
    get{ return number; }
    set{ number = value; }
  }
}<\/p>\n

\/**\/\/\/\/ <summary>
\/\/\/  ChainApp Application
\/\/\/ <\/summary>
public class ChainApp
{
  public static void Main( string[] args )
  {
    \/\/ Setup Chain of Responsibility
    Director Larry = new Director( \"Larry\" );
    VicePresident Sam = new VicePresident( \"Sam\" );
    President Tammy = new President( \"Tammy\" );
    Larry.SetSuccessor( Sam );
    Sam.SetSuccessor( Tammy );<\/p>\n

    \/\/ Generate and process different requests
    PurchaseRequest rs = new PurchaseRequest( 2034, 350.00, \"Supplies\" );
    Larry.ProcessRequest( rs );<\/p>\n

    PurchaseRequest rx = new PurchaseRequest( 2035, 32590.10, \"Project X\" );
    Larry.ProcessRequest( rx );<\/p>\n

    PurchaseRequest ry = new PurchaseRequest( 2036, 122100.00, \"Project Y\" );
    Larry.ProcessRequest( ry );
  }
}
<\/code><\/p>\n

\u516d\u3001 \u8d23\u4efb\u94fe\u6a21\u5f0f\u7684\u5b9e\u73b0
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<\/p>\n","protected":false},"excerpt":{"rendered":"

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