Chain of Responsibility(责任链)

文章目录

1. 责任链模式

责任链模式

• 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。将这些对象连成一个链，沿着链条传递请求，知道有一个对象处理为止。

public interface PhoneMakerAssembly {
    void setNextPoint(PhoneMakerAssembly successor);
    PhoneMakerAssembly getNextPoint();
    void build(String partName);
}

public abstract class AbstractPhoneMakerAssembly implements PhoneMakerAssembly {
    private PhoneMakerAssembly nextpoint;
    @Override public void setNextPoint(PhoneMakerAssembly successor) {
        nextpoint=successor;
    }

    @Override public PhoneMakerAssembly getNextPoint() {
        return nextpoint;
    }
}

public class Framemaker extends AbstractPhoneMakerAssembly{

    @Override public void build(String partName) {
        if ("main".equals(partName)){
            System.out.println("构建主体框架");
            return;
        }
        System.out.println("构建失败，寻找下家");
        getNextPoint().build(partName);
    }
}

public class CameraMaker extends AbstractPhoneMakerAssembly{

    @Override public void build(String partName) {
        if ("camera".equals(partName)){
            System.out.println("构建摄像头框架");
            return;
        }
        System.out.println("构建失败，寻找下家");
        getNextPoint().build(partName);
    }
}

public class ScreenMaker extends AbstractPhoneMakerAssembly{

    @Override public void build(String partName) {
        if ("screen".equals(partName)){
            System.out.println("构建屏幕框架");
            return;
        }
        System.out.println("构建失败，寻找下家");
        getNextPoint().build(partName);
    }
}

public class DefaultMaker implements PhoneMakerAssembly {
    @Override public void setNextPoint(PhoneMakerAssembly successor) {

    }

    @Override public PhoneMakerAssembly getNextPoint() {
        return null;
    }

    @Override public void build(String partName) {
        System.out.println("未找到支持的构建器");
    }
}

public class App {

    public static void main(String[] args) {
        PhoneMakerAssembly maker1=new Framemaker();
        PhoneMakerAssembly maker2=new CameraMaker();
        PhoneMakerAssembly maker3=new ScreenMaker();

        maker1.setNextPoint(maker2);
        maker2.setNextPoint(maker3);
        maker3.setNextPoint(new DefaultMaker());
        //注意链条是代码构造出来的

        maker1.build("screen");
        maker1.build("main");
        maker1.build("camera");

        maker1.build("xxx");
    }
}