[關鍵字]:java,design pattern,設計模式,《Java與模式》,Chain of Responsibility,責任鏈模式
[環境]:StarUML5.0 + JDK6
[作者]:Winty (wintys@gmail.com)
[正文]:

package pattern.chainofresponsibility;

/**
 * 責任鏈模式:Chain of Responsibility
 * @version 2009-5-9
 * @author Winty(wintys@gmail.com)
 */
public class ChainOfResponsibilityTest{
    public static void main(String[] args){
        Handler handler1 = new ConcreteHandler1();
        Handler handler2 = new ConcreteHandler2();
        Handler handler3 = new ConcreteHandler3();

        //設置責任鏈
        handler3.setSuccessor(handler2);
        handler2.setSuccessor(handler1);

        //發送命令
        handler3.handleRequest();
    }
}

/**
 *抽象處理者
 */
abstract class Handler{
    protected Handler successor;

    public Handler getSuccessor(){
        return successor;
    }

    public void setSuccessor(Handler successor){
        this.successor = successor;
    }

    public abstract void handleRequest();
}

/**
 *具體處理者
 */
class ConcreteHandler1 extends Handler{
    public void handleRequest(){
        if(getSuccessor() != null){
            System.out.print("Request passed:from class Concrete1");
            System.out.println(" to class" + getSuccessor().getClass().getName());

            getSuccessor().handleRequest();
        }
        else{
            System.out.println("Request handled in ConcreteHandler1");
        }
    }
}

/**
 *具體處理者
 */
class ConcreteHandler2  extends Handler{
    public void handleRequest(){
        if(getSuccessor() != null){
            System.out.print("Request passed:from class Concrete2");
            System.out.println(" to class " + getSuccessor().getClass().getName());

            getSuccessor().handleRequest();
        }
        else{
            System.out.println("Request handled in ConcreteHandler2");
        }
    }
}

/**
 *具體處理者
 */
class ConcreteHandler3  extends Handler{
    public void handleRequest(){
        if(getSuccessor() != null){
            System.out.print("Request passed:from class Concrete3");
            System.out.println(" to class " + getSuccessor().getClass().getName());

            getSuccessor().handleRequest();
        }
        else{
            System.out.println("Request handled in ConcreteHandler3");
        }
    }
}