/** * 责任链模式:最形象的例子就是过滤器,一个字符串,经过一连串的过滤器,最后得到想要的字符串,例如,过滤HTMl标签,过滤敏感字符,过滤特殊字符 * 模式特点: 一个过滤器接口,多个实现类,其中一个实现类叫过滤器链,它里面有个集合存所有的过滤器,执行过滤时,就是从集合中拿出一个个过滤器来执行 * 相当于遍历,但跟遍历的表现形式不一样: * * * *///定义过滤器链public class FilterChain implements IFilter{    private List
     
       list=new ArrayList<>();//存储过滤器    private int index;//过滤器集合的执行索引    //注册过滤器    public void addFilter(IFilter filter){        list.add(filter);    }    //过滤方法    @Override    public void filter(Request req, Response resp, FilterChain chain) {        //当执行完所有的过滤器后就停止        if(index>=list.size()){            return;        }        //取出其中一个过滤器        IFilter filter = list.get(index);        index++;//索引指向下一个过滤器的索引        //执行过滤器的过滤方法,这里传一个this对象作为参数,是为了在filter过滤器中还能再次调用chain.filter方法        //这样的话,每次进来这个方法,index索引就可以指向下个过滤器,因此相当于遍历集合了        filter.filter(req,resp,this);    }}public interface IFilter {    void filter(Request req,Response resp,FilterChain chain);}//a标签过滤器public class AtagFilter implements IFilter {    @Override    public void filter(Request req, Response resp, FilterChain chain) {        String reqParam = req.getReqParam();        reqParam=reqParam.replace("
      ","");        String replace = reqParam.replace("", "");        req.setReqParam(replace);        resp.setResponseStr(replace);        chain.filter(req,resp,chain);    }}//敏感字符过滤器public class SensitiveFilter implements IFilter {    @Override    public void filter(Request req, Response resp, FilterChain chain) {        String reqParam = req.getReqParam();        reqParam = reqParam.replace("脏话", "");        req.setReqParam(reqParam);        resp.setResponseStr(reqParam);        chain.filter(req,resp,chain);    }}//特殊字符过滤器public class SpecialCharFilter implements IFilter {    @Override    public void filter(Request req, Response resp, FilterChain chain) {        String reqParam = req.getReqParam();        reqParam=reqParam.replace("#","");        String replace = reqParam.replace("$", "");        req.setReqParam(replace);        resp.setResponseStr(replace);        chain.filter(req,resp,chain);    }}//请求对象public class Request {    //请求参数    private String reqParam;    public String getReqParam() {        return reqParam;    }    public void setReqParam(String reqParam) {        this.reqParam = reqParam;    }}//返回对象public class Response {    private String responseStr;    public String getResponseStr() {        return responseStr;    }    public void setResponseStr(String responseStr) {        this.responseStr = responseStr;    }}public class Test {    public static void main(String[] args) {        Request request = new Request();//创建请求对象        request.setReqParam("$
      www.baidu 脏话#");        Response response = new Response();//创建响应对象        FilterChain filterChain = new FilterChain();//创建责任链对象        filterChain.addFilter(new AtagFilter());//注册a标签过滤器        filterChain.addFilter(new SensitiveFilter());//注册敏感字符过滤器        filterChain.addFilter(new SpecialCharFilter());//注册特殊字符过滤器        filterChain.filter(request,response,filterChain);//调用过滤方法        //打印返回值,因为上面filter方法传入的参数是对象,引用类型,所以在过滤器中对该对象的改变会改变原对象        System.out.println(response.getResponseStr());    }}