责任链模式

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设计模式/行为型设计模式

简述

为了避免请求的发送者和接收者之间的耦合关系，使多个接收对象都有机会处理请求。
将这些对象练成一条链，并沿着这条链传递该请求，直到有一个对象处理它为止

UML图

代码

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// 绘画接口
public interface Drawable {
    void draw();
}

@Slf4j
public class DrawHead implements Drawable {
    private Drawable drawable;

    public DrawHead(Drawable drawable) {
        this.drawable = drawable;
    }

    @Override
    public void draw() {
        log.debug(“DrawHead 画头部--");
                drawable.draw();
    }
}

@Slf4j
public class DrawBody implements Drawable {
    private Drawable drawable;

    public DrawBody(Drawable drawable) {
        this.drawable = drawable;
    }

    @Override
    public void draw() {
        log.debug(“DrawBody 画身体--");
                drawable.draw();
    }
}

@Slf4j
public class DrawFoot implements Drawable {
    @Override
    public void draw() {
        log.debug(“DrawFoot 画脚 — “);
    }
}

// 客户端
public class Client {
    public static void main(String[] args) {
        Drawable drawFoot = new DrawFoot();
        Drawable drawBody = new DrawBody(drawFoot);
        Drawable drawHead = new DrawHead(drawBody);
        drawHead.draw();
    }
}