什么意思呢？

就是有這么一個鏈條，你也不用管它具體怎么鏈的，你只需要給它一個輸入，它就能找到恰當的一環來處理你的輸入，就這么個意思。很顯然，這對于使用者來說是非常方便的。

類圖

類圖.png

調用

package com.company;

public class Main {

    public static void main(String[] args) {
    // write your code here
        AbstractReceiver chain = installChain();

        chain.chainElementInput(AbstractReceiver.receiver2);
        chain.chainElementInput(AbstractReceiver.receiver1);
        chain.chainElementInput(AbstractReceiver.receiver3);
    }

    /**
     * 組裝責任鏈
     * @return
     */
    public static AbstractReceiver installChain() {
        AbstractReceiver receiver1 = new Receiver1(AbstractReceiver.receiver1);
        AbstractReceiver receiver2 = new Receiver2(AbstractReceiver.receiver2);
        AbstractReceiver receiver3 = new Receiver3(AbstractReceiver.receiver3);

        receiver1.setNextRecevier(receiver2);
        receiver2.setNextRecevier(receiver3);

        return receiver1;
    }
}

結果

com.company.Receiver2
com.company.Receiver1
com.company.Receiver3

Process finished with exit code 0

抽象接收者

package com.company;

public abstract class AbstractReceiver {
    public static int receiver1 = 1;
    public static int receiver2 = 2;
    public static int receiver3 = 3;

    protected int receiverIndex;

    protected AbstractReceiver nextRecevier;

    public void setNextRecevier(AbstractReceiver nextRecevier) {
        this.nextRecevier = nextRecevier;
    }

    /**
     * 控制恰當鏈中的某一環來處理。
     * @param inputIndex
     */
    protected void chainElementInput(int inputIndex) {
        if (inputIndex <= this.receiverIndex) {
            printInformation(this.receiverIndex);
            return;
        } else {
            this.nextRecevier.chainElementInput(inputIndex);
        }
    }

    abstract public void printInformation(int receiverIndex);
}

接收者1

package com.company;

public class Receiver1 extends AbstractReceiver {
    public Receiver1(int index) {
        this.receiverIndex = index;
    }

    @Override
    public void printInformation(int receiverIndex) {
        System.out.println(this.getClass().getName());
    }
}

接收者2

package com.company;

public class Receiver2 extends AbstractReceiver {
    public Receiver2(int index) {
        this.receiverIndex = index;
    }

    @Override
    public void printInformation(int receiverIndex) {
        System.out.println(this.getClass().getName());
    }
}

接收者3

package com.company;

public class Receiver3 extends AbstractReceiver {
    public Receiver3(int index) {
        this.receiverIndex = index;
    }

    @Override
    public void printInformation(int receiverIndex) {
        System.out.println(this.getClass().getName());
    }
}

多謝捧場

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