责任链设计模式

梁云亮发布时间：2019-10-26 18:26:04 ，浏览量：2

示例：实现网络请求中见的网络文本过滤功能，比如： 1、敏感字过滤 2、特殊字符过滤 3、Emoji表情过滤 ……

版本一

public static void main(String[] args) {
    String msg ="alert('这是一个差生凸^-^凸')";
    String res =  msg.replace('',']')
            .replaceAll("差生","后进生")
            .replace("凸^-^凸","伤心"); //此处必须得使用replace方法，不能使用replaceAll
    System.out.println(res);
}

结果：在这里插入图片描述

版本二：专门抽取出来一个用来处理文本的工具类

文件处理类

public class MsgProcessor {

    private String msg;

    public void setMsg(String msg) {
        this.msg = msg;
    }


    public String process() {
        return msg.replace('', ']')
                .replaceAll("差生", "后进生")
                .replace("凸^-^凸", "伤心");
    }
}

测试类

public class Demo {
    private static String msg ="alert('这是一个差生凸^-^凸')";

    public static void main(String[] args) {
        MsgProcessor processor = new MsgProcessor();
        processor.setMsg(msg);
        String res = processor.process();
        System.out.println(res);
    }
}

版本三：针对每一种文本过滤功能提供单独的类

针对文本过滤功能提供一个统一的Filter接口

public interface MsgFilter {
    String doFilter(String msg);
}

过滤敏感字的功能类

public class SensitiveFilter implements  MsgFilter {
    @Override
    public String doFilter(String msg) {
        return msg.replaceAll("差生", "后进生");
    }
}

过滤特殊字符的功能类

public class HtmlFilter implements MsgFilter {
    @Override
    public String doFilter(String msg) {
        return msg.replace('', ']');
    }
}

过滤Emoji表情的功能类

public class EmojiFilter implements MsgFilter {
    @Override
    public String doFilter(String msg) {
        return msg.replace("凸^-^凸", "伤心");
    }
}

调用过滤器实现文本过滤的类

public class MsgProcessor {

    private String msg;

    public void setMsg(String msg) {
        this.msg = msg;
    }

    private MsgFilter[] filters = {new HtmlFilter(),new SensitiveFilter(),new EmojiFilter()};

    public String process() {
        for(MsgFilter filter : filters){
            msg = filter.doFilter(msg);
        }
        return msg;
    }
}

测试代码

public class Demo {
    private static String msg ="alert('这是一个差生凸^-^凸')";

    public static void main(String[] args) {
        MsgProcessor processor = new MsgProcessor();
        processor.setMsg(msg);
        String res = processor.process();
        System.out.println(res);
    }
}

版本四：将过滤器链加入到过滤器中

在这里插入图片描述

添加新的类FilterChain，用来模拟责任链功能

public class FilterChain implements MsgFilter {
    List filters = new ArrayList();

    public FilterChain addFilter(MsgFilter filter) {
        filters.add(filter);
        return this;
    }

    @Override
    public String doFilter(String msg) {
        for (MsgFilter filter : filters) {
            msg = filter.doFilter(msg);
        }
        return msg;
    }
}

修改MsgProcessor类

public class MsgProcessor {

    private String msg;
    private FilterChain filterChain;

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public void setFilterChain(FilterChain filterChain) {
        this.filterChain = filterChain;
    }

    public String process() {
        return  filterChain.doFilter(msg);
    }
}

测试代码：

public class Demo {
    private static String msg = "alert('这是一个差生凸^-^凸')";

    public static void main(String[] args) {
        FilterChain filterChain1 = new FilterChain();
        filterChain1.addFilter(new SensitiveFilter());
        filterChain1.addFilter(new HtmlFilter());

        FilterChain filterChain2 = new FilterChain();
        filterChain2.addFilter(new EmojiFilter());

        filterChain1.addFilter(filterChain2);

        MsgProcessor processor = new MsgProcessor();
        processor.setMsg(msg);
        processor.setFilterChain(filterChain1);

        String res = processor.process();
        System.out.println(res);
    }
}

版本5：模拟tomcat中消息从客户端发往服务器端，服务器端也有反馈的功能

Filter接口：

public interface MsgFilter {
    void doFilter(Request request,Response response,FilterChain filterChain);
}

特殊字符过滤类

public class HtmlFilter implements MsgFilter {
    @Override
    public void doFilter(Request request,Response response,FilterChain filterChain) {
       request. msg =   request.msg.replace('', ']')+" --HtmlFilter() ";
        filterChain.doFilter(request,response,filterChain);

        response.msg += "-- HtmlFilter() ";
    }
}

敏感字过滤类

public class SensitiveFilter implements  MsgFilter {
    @Override
    public void doFilter(Request request,Response response,FilterChain filterChain) {
        request. msg =   request.msg.replaceAll("差生", "后进生")+" --SensitiveFilter() ";
        filterChain.doFilter(request,response,filterChain);

        response.msg += "-- SensitiveFilter() ";
    }
}

Emoji过滤类

public class EmojiFilter implements MsgFilter {
    @Override
    public void doFilter(Request request,Response response,FilterChain filterChain) {
        request. msg =   request.msg.replace("凸^-^凸", "伤心")+" --EmojiFilter() ";
        filterChain.doFilter(request,response,filterChain);

        response.msg += "-- EmojiFilter() ";
    }
}

过滤器链

public class FilterChain implements MsgFilter {
    int index = 0;
    List filters = new ArrayList();

    public FilterChain addFilter(MsgFilter filter) {
        filters.add(filter);
        return this;
    }

    @Override
    public void doFilter(Request request,Response response,FilterChain filterChain) {
        if(index == filters.size()) {
            return;
        }
        MsgFilter filter = filters.get(index);
        index ++;
        filter.doFilter(request,response,filterChain);
    }
}

测试代码

public class Demo {


    private static String msg = "alert('这是一个差生凸^-^凸')";

    public static void main(String[] args) {
        Request request = new Request();
        request.msg = msg;
        Response response = new Response();
        response.msg  = "response: ";


        FilterChain filterChain = new FilterChain().addFilter(new SensitiveFilter())
                .addFilter(new HtmlFilter())
                .addFilter(new EmojiFilter());

        filterChain.doFilter(request,response,filterChain);

        System.out.println(request.msg);
        System.out.println(response.msg);
    }
}

结果：在这里插入图片描述

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