设计模式开始--职责链模式

职责链的模式

一、作用

多个对象都有机会处理请求，从而避免请求的发送者和接受者之间的耦合关系，将对象连成一条链，并沿着这条链传递该请求，直到有一个对象可以处理它

二、类图

三、实现

（1）定义Handle

public abstract class Handle {
    protected Handle successor;
    public void setSeccessor(Handle successor)
    {
        this.successor = successor;
    }
    public abstract void handleRequest(int request);
}
public class ConcreteHandleOne extends Handle {
    @Override
    public void handleRequest(int request) {
        if(request >= 0 && request < 10)
        {
            System.out.println("One 处理请求"+request);
        }
        else if(successor != null)
        {
            successor.handleRequest(request);
        }
    }
}
public class ConcreteHandleTwo extends Handle {
    @Override
    public void handleRequest(int request) {
        if(request >= 10 && request < 20)
        {
            System.out.println("Two 处理请求"+request);
        }
        else if(successor != null)
        {
            successor.handleRequest(request);
        }
    }
}
public class ConcreteHandleThree extends Handle {
    @Override
    public void handleRequest(int request) {
        if(request > 20) 
        {
            System.out.println("Three 处理请求"+request);
        }
        else if(successor != null)
        {
            successor.handleRequest(request);
        }
    }
}

(2)Client测试类

public class Client {
    public static void main(String[] args) {
        Handle h1 = new ConcreteHandleOne();
        Handle h2 = new ConcreteHandleTwo();
        Handle h3 = new ConcreteHandleThree();
        h1.successor = h2;
        h2.successor = h3;
        int request = 14;
        h1.handleRequest(request);
    }
}