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Chain of Responsibility

7,080 bytes added, 21:58, 2 April 2007
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=== Java Example ===
Some Code'''Example 1''' -- This code can be found at [http://www.javacamp.org/designPattern/chains.html www.Javacamp.org]<pre>import java.io.*; abstract class PurchasePower {  protected final double base = 500; protected PurchasePower successor;  public void setSuccessor(PurchasePower successor){ this.successor = successor; }  abstract public void processRequest(PurchaseRequest request); }  class Manager extends PurchasePower {  private final double ALLOWABLE = 10 * base;  public void processRequest(PurchaseRequest request ) { if( request.getAmount() < ALLOWABLE ) System.out.println("Manager will approve $"+ request.getAmount()); else if( successor != null) successor.processRequest(request); } } class Director extends PurchasePower { private final double ALLOWABLE = 20 * base;  public void processRequest(PurchaseRequest request ) { if( request.getAmount() < ALLOWABLE ) System.out.println("Director will approve $"+ request.getAmount()); else if( successor != null) successor.processRequest(request); }} class VicePresident extends PurchasePower { private final double ALLOWABLE = 40 * base;  public void processRequest(PurchaseRequest request) { if( request.getAmount() < ALLOWABLE ) System.out.println("Vice President will approve $" + request.getAmount()); else if( successor != null ) successor.processRequest(request); }} class President extends PurchasePower { private final double ALLOWABLE = 60 * base; public void processRequest(PurchaseRequest request){ if( request.getAmount() < ALLOWABLE ) System.out.println("President will approve $" + request.getAmount()); else System.out.println( "Your request for $" + request.getAmount() + " needs a board meeting!"); }} class PurchaseRequest { private int number; private double amount; private String purpose;  public PurchaseRequest(int number, double amount, String purpose){ this.number = number; this.amount = amount; this.purpose = purpose; }  public double getAmount() { return amount; } public void setAmount(double amt){ amount = amt; } public String getPurpose() { return purpose; } public void setPurpose(String reason) { purpose = reason; }  public int getNumber(){ return number; } public void setNumber(int num) { number = num; } } class CheckAuthority { public static void main(String[] args) throws Exception{ Manager manager = new Manager(); Director director = new Director(); VicePresident vp = new VicePresident(); President president = new President(); manager.setSuccessor(director); director.setSuccessor(vp); vp.setSuccessor(president); //enter ctrl+c to kill. while (true) { System.out.println("Enter the amount to check who should approve your expenditure."); System.out.print(">"); double d = Double.parseDouble(new BufferedReader(new InputStreamReader(System.in)).readLine()); manager.processRequest(new PurchaseRequest(0, d, "General")); }  }}</pre>[[Image:javacodeSolution.GIF]]
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=== C# Example ===
'''Example 1''' - This code can be found at [http://www.c-sharpcorner.com/UploadFile/rmcochran/chain_of_command01172007143425PM/chain_of_command.aspx www.c-sharpcorner.com]
Our command will be a PhoneCall class with one method "Converse()" which is our command.
*Hello. This is ACME Movie Rentals with an important message.
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'''Example 2''' - This code can be found at [http://www.dofactory.com/Patterns/PatternChain.aspx#_self1 www.dofactory.com]
<pre>
using System;
namespace DoFactory.GangOfFour.Chain.RealWorld
 
{
 
// MainApp test application
 
class MainApp
{
static void Main()
{
// Setup Chain of Responsibility
Director Larry = new Director();
VicePresident Sam = new VicePresident();
President Tammy = new President();
Larry.SetSuccessor(Sam);
Sam.SetSuccessor(Tammy);
 
// Generate and process purchase requests
Purchase p = new Purchase(2034, 350.00, "Supplies");
Larry.ProcessRequest(p);
 
p = new Purchase(2035, 32590.10, "Project X");
Larry.ProcessRequest(p);
 
p = new Purchase(2036, 122100.00, "Project Y");
Larry.ProcessRequest(p);
 
// Wait for user
Console.Read();
}
}
 
// "Handler"
 
abstract class Approver
{
protected Approver successor;
 
public void SetSuccessor(Approver successor)
{
this.successor = successor;
}
 
public abstract void ProcessRequest(Purchase purchase);
}
 
// "ConcreteHandler"
 
class Director : Approver
{
public override void ProcessRequest(Purchase purchase)
{
if (purchase.Amount < 10000.0)
{
Console.WriteLine("{0} approved request# {1}",
this.GetType().Name, purchase.Number);
}
else if (successor != null)
{
successor.ProcessRequest(purchase);
}
}
}
 
// "ConcreteHandler"
 
class VicePresident : Approver
{
public override void ProcessRequest(Purchase purchase)
{
if (purchase.Amount < 25000.0)
{
Console.WriteLine("{0} approved request# {1}",
this.GetType().Name, purchase.Number);
}
else if (successor != null)
{
successor.ProcessRequest(purchase);
}
}
}
 
// "ConcreteHandler"
 
class President : Approver
{
public override void ProcessRequest(Purchase purchase)
{
if (purchase.Amount < 100000.0)
{
Console.WriteLine("{0} approved request# {1}",
this.GetType().Name, purchase.Number);
}
else
{
Console.WriteLine(
"Request# {0} requires an executive meeting!",
purchase.Number);
}
}
}
 
// Request details
 
class Purchase
{
private int number;
private double amount;
private string purpose;
 
// Constructor
public Purchase(int number, double amount, string purpose)
{
this.number = number;
this.amount = amount;
this.purpose = purpose;
}
 
// Properties
public double Amount
{
get{ return amount; }
set{ amount = value; }
}
 
public string Purpose
{
get{ return purpose; }
set{ purpose = value; }
}
 
public int Number
{
get{ return number; }
set{ number = value; }
}
}
}
</pre>
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== External Links References ==*External Links# [http://www.javaworld.com/javaworld/jw-08-2003/jw-0829-designpatterns.html Java World]# [http://www.developer.com/java/other/article.php/631261 Developer.com]# [http://www.oodesign.com/oo_design_patterns/behavioral_patterns/chain_of_responsibility.html OODesign.com]# [http://codebetter.com/blogs/jeremy.miller/archive/2005/11/06/134359.aspx Codebetter.com]# [http://www.c-sharpcorner.com/UploadFile/rmcochran/chain_of_command01172007143425PM/chain_of_command.aspx C-Sharpcorner.com]# [http://www.javacamp.org/designPattern/chains.html Javacamp.org]
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--[[User:Djeyarat|Djeyarat]] 1521:4956, 2 April 2007 (EDT)
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