责任链

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
/**
 * @description: 责任链
 * @Author: wangchao
 * @Date: 2022/1/16
 */
interface Interceptor {
    Object plugin(Object target, InterceptorChain chain);
}
class InterceptorA implements Interceptor {
    @Override
    public Object plugin(Object target, InterceptorChain chain) {
        System.out.println("InterceptorA");
        //  控制 InterceptorChain 是否再调一次，即迭代器是否遍历下一个
        return chain.plugin(target);
    }
}
class InterceptorB implements Interceptor {
    @Override
    public Object plugin(Object target, InterceptorChain chain) {
        System.out.println("InterceptorB");
        return chain.plugin(target);
    }
}
class InterceptorC implements Interceptor {
    @Override
    public Object plugin(Object target, InterceptorChain chain) {
        System.out.println("InterceptorC");
        return target;
    }
}
class InterceptorChain {
    private List<Interceptor> interceptorList = new ArrayList<>();
    private Iterator<Interceptor> iterator;
    public void addInterceptor(Interceptor interceptor) {
        interceptorList.add(interceptor);
    }
    public Object pluginAll(Object target) {
        for (Interceptor interceptor : interceptorList) {
            target = interceptor.plugin(target, this);
        }
        return target;
    }
    public Object plugin(Object target) {
        if (iterator == null) {
            iterator = interceptorList.iterator();
        }
        // 注意：这里使用 if 而不是 while，每次触发都依靠 plugin
        if (iterator.hasNext()) {
            Interceptor next = iterator.next();
            next.plugin(target, this);
        }
        return target;
    }
}
public class InterceptDemo {
    public static void main(String[] args) {
        Interceptor interceptorA = new InterceptorA();
        Interceptor interceptorB = new InterceptorB();
        Interceptor interceptorC = new InterceptorC();
        InterceptorChain interceptorChain = new InterceptorChain();
        interceptorChain.addInterceptor(interceptorA);
        interceptorChain.addInterceptor(interceptorB);
        interceptorChain.addInterceptor(interceptorC);
        interceptorChain.plugin(new Object());
    }
}