责任链模式

当有多个对象可以处理同一请求，具体哪个对象要到运行时再定，客户端只需将请求提交到责任链上，无需关心谁处理

适用场景：采购审批子系统、OA中假条审批模块

public interface ChainHandler {

    public void operator();
    
}

public abstract class AbstractChainHandler {

    private ChainHandler handler;
    
    public ChainHandler getHandler(){
        return handler;
    }
    
    public void setHandler(ChainHandler handler){
        this.handler = handler;
    }
    
}

public class MyChainHandler extends AbstractChainHandler implements ChainHandler {

    private String name;
    
    public MyChainHandler(String name) {
        this.name = name;
    }
    
    @Override
    public void operator() {
        System.out.println(name + "开始处理");
        ChainHandler handler = getHandler();
        if(null != handler){
            handler.operator();
        }else{
            System.out.println("处理完毕");
        }
    }

}

public class ChainMain {

    public static void main(String[] args) {
        MyChainHandler handler1 = new MyChainHandler("h1");
        MyChainHandler handler2 = new MyChainHandler("h2");
        MyChainHandler handler3 = new MyChainHandler("h3");
        MyChainHandler handler4 = new MyChainHandler("h4");
        
        handler1.setHandler(handler2);
        handler2.setHandler(handler3);
        handler3.setHandler(handler4);
        
        handler1.operator();
    }

}

输出：

h1开始处理
h2开始处理
h3开始处理
h4开始处理
处理完毕