二十一 Java设计模式解析(责任链模式)

1️⃣概念

定义 : 为请求创建一个接收此次请求对象的链;
类型 : 行为型;

2️⃣适用场景

一个请求的处理需要多个对象当中的一个或几个协作处理;

3️⃣优点

对请求的发送者和接收者进行解耦;
责任链可以动态的组合;

4️⃣缺点

如果责任链太长或者处理时间太长都会影响性能;
责任链有可能过多;

5️⃣责任链模式Coding

1 创建Course类

public class Course {
    private String name;
    private String article;
    private String video;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getArticle() {
        return article;
    }

    public void setArticle(String article) {
        this.article = article;
    }

    public String getVideo() {
        return video;
    }

    public void setVideo(String video) {
        this.video = video;
    }

    @Override
    public String toString() {
        return "Course{" +
                "name='" + name + '\'' +
                ", article='" + article + '\'' +
                ", video='" + video + '\'' +
                '}';
    }
}

2 创建抽象类Approver

public abstract class Approver {
    protected Approver approver;

    public void setNextApprover(Approver approver){
        this.approver = approver;
    }
    public abstract void deploy(Course course);
}

3 创建ArticleApprover类继承Approver

public class ArticleApprover extends Approver {
    @Override
    public void deploy(Course course) {
        if(StringUtils.isNotEmpty(course.getArticle())){
            System.out.println(course.getName()+"有笔记总结,批准");
            if(approver != null){
                approver.deploy(course);
            }
        }else{
            System.out.println(course.getName()+"没有笔记总结,不批准,流程结束");
            return;
        }
    }
}

4 创建VideoApprover类继承Approver

public class VideoApprover extends Approver{
    @Override
    public void deploy(Course course) {
        if(StringUtils.isNotEmpty(course.getVideo())){
            System.out.println(course.getName()+"含有讲解视频,批准");
            if(approver != null){
                approver.deploy(course);
            }
        }else{
            System.out.println(course.getName()+"没有讲解视频,不批准,流程结束");
            return;
        }
    }
}

5 UML类图

6 编写测试类

public class Test {
    public static void main(String[] args) {
        Approver articleApprover = new ArticleApprover();
        Approver videoApprover = new VideoApprover();

        Course course = new Course();
        course.setName("Java设计模式");
        course.setArticle("Java设计模式手记");
        course.setVideo("Java设计模式视频");

        articleApprover.setNextApprover(videoApprover);

        articleApprover.deploy(course);
    }
}

6️⃣责任链模式源码解析

javax.servlet.Filter FilterChain