Chain of Responsibility责任链

Chain of Responsibility 责任链

责任链模式，举个例子就是servlet的Filter和FilterChain,泛型为Filter的list作为FilterChain的成员变量。相当于责任链上的每一个节点，每个过滤器都承担自己的责任，在FilterChain执行doFilter后过滤信息或者请求。

public class Cor {
    public static void main(String[] args){
        Request request = new Request();
        request.str = "AABB";
        Response response = new Response();
        response.str = "response";
        FilterPart1 filterPart1 = new FilterPart1();
        FilterPart2 filterPart2 = new FilterPart2();
        FilterChain filterChain = new FilterChain();
        filterChain.add(filterPart1).add(filterPart2);
        filterChain.doFilter(request,response);
        System.out.println(request.str);
        System.out.println(response.str);
    }
}
interface Filter{
    void doFilter(Request req,Response res,FilterChain filterChain);
}
class Request{
    String str;
}
class Response{
    String str;
}
class FilterPart1 implements Filter{
    @Override
    public void doFilter(Request req, Response res, FilterChain filterChain) {
        req.str = req.str.replace('A','X');
        filterChain.doFilter(req,res);
        res.str+="FilterPart1";
    }
}
class FilterPart2 implements Filter{
    @Override
    public void doFilter(Request req, Response res, FilterChain filterChain) {
        req.str = req.str.replace('B','Z');
        filterChain.doFilter(req,res);
        res.str+="FilterPart2";
    }
}
class FilterChain{
    ArrayList<Filter> filters = new ArrayList<>();
    int index;
    public FilterChain add(Filter filter){
        filters.add(filter);
        return this;
    }
    public void doFilter(Request req,Response res){
        if(index<filters.size()){
            filters.get(index++).doFilter(req,res,this);
        }
    }
}