职责链模式

看代码是学程序最好的方法，先看代码：

package rowsy.learn;

import java.util.ArrayList;

interface Filter {
	
	public void doFilter(String request);
	
}

class Filter1 implements Filter {

	@Override
	public void doFilter(String request) {

		System.out.println("do filter 1");

	}

}

class Filter2 implements Filter {

	@Override
	public void doFilter(String request) {

		System.out.println("do filter 2");

	}

}

class FilterChain implements Filter {

	private ArrayList<Filter> filterChain = new ArrayList<Filter>();

	public FilterChain addFilter(Filter filter) {

		filterChain.add(filter);

		return this;

	}

	@Override
	public void doFilter(String request) {

		for (Filter filter : filterChain) {
			filter.doFilter(request);
		}

	}

}

public class ChainOfResponsibility {

	public static void main(String[] args) {

		FilterChain filterChain = new FilterChain();
		filterChain.addFilter(new Filter1()).addFilter(new Filter2())
				.addFilter(new Filter1());
		filterChain.doFilter("hello");

	}

}

运行结果输出：

do filter 1
do filter 2
do filter 1

职责链设计模式主要解决的问题是让多个对象都有机会处理请求，从而避免请求的发送者和请求的接受者的耦合关系。

将处理请求的对象连成一个链，请求按照这个链依次传递，直到请求被处理为止。