Java设计模式---ChainOfResponsibility责任链模式

来源：cnblogs　　作者：DingYu　　时间：2018/11/29 9:23:41　　对本文有异议

参考于 :

　　大话设计模式

　　马士兵设计模式视频

　　代码参考于马士兵设计模式视频

　　写在开头：职责链模式：使多个对象都有机会处理请求，从而避免请求的发送者和接收者之间的耦合关系

　　图来自大话设计模式，下面我的代码中，Clien是t依赖于Handler1和Handler2的，不过可以使用配置文件或者直接给Filter集合初始化来解决这种依赖。

1.场景

　　在网上评论一句话，往往会经过一系列的处理，有没有敏感词之类，现在我们来模拟一下。

　　把<html>，o.o，和谐

　　换成 [html]，^v^，/*河蟹*/

2.不使用职责链模式

package com.dingyu.ChainOfResponsibility;

/**
 * 重点在于模式，故逻辑暂时不考虑
 * 
 * @author dingyu
 *
 */
public class Client01 {
    public static void main(String[] args) {
        String s = "<html>，o.o，和谐";
        s = s.replace("<", "[").replace(">", "]").replace("和谐", "/*河蟹*/").replace("o.o", "^v^");
        System.out.println(s);
    }
}

　　缺点：过滤无法复用，无法记录过滤顺序。

3.使用职责链模式

package com.dingyu.ChainOfResponsibility;
/**
 * 过滤器,doFilter处理msg字符串
 * @author dingyu
 *
 */
public interface Filter {
    public String doFilter(String msg);
}

package com.dingyu.ChainOfResponsibility;

/**
 * 处理html符号
 * 测试用的，逻辑不是很严谨
 * @author dingyu
 *
 */
public class HTMLFilter implements Filter {

    @Override
    public String doFilter(String msg) {
        return msg.replace("<", "[").replace(">", "]");
    }

}

package com.dingyu.ChainOfResponsibility;
/**
 * 过滤敏感词汇
 * @author dingyu
 *
 */
public class SensitiveWordFilter implements Filter {

    @Override
    public String doFilter(String msg) {
        return msg.replace("和谐", "/*河蟹*/");
    }

}

package com.dingyu.ChainOfResponsibility;
/**
 * 处理符号
 * @author dingyu
 *
 */
public class SymbolFilter implements Filter {

    @Override
    public String doFilter(String msg) {
        return msg.replace("o.o", "^v^");
    }

}

package com.dingyu.ChainOfResponsibility;

import java.util.ArrayList;
import java.util.List;

public class Client {
    private static List<Filter> filters = new ArrayList<Filter>();
    private static int index = 0;

    public static void main(String[] args) {
        String s = "<html>，o.o，和谐";
        filters.add(new HTMLFilter());
        filters.add(new SymbolFilter());
        filters.add(new SensitiveWordFilter());
        for (Filter filter : filters) {
            s = filter.doFilter(s);
        }
        System.out.println(s);
    }
}

　　虽然使用职责链模式，但仍然有缺点，上面的顺序是先HTML,然后Symbol，最后SensitiveWord，这三个构成一个过滤链条，如果有一天我需要把另一个过滤链条插入到这根链条中间，实现起来很麻烦。

4.改进职责链模式

package com.dingyu.ChainOfResponsibility;

import java.util.ArrayList;
import java.util.List;
/**
 * 
 * @author dingyu
 *
 */
public class FilterChain implements Filter {

    private List<Filter> filters = new ArrayList<Filter>();

    public void add(Filter filter) {
        filters.add(filter);
    }

    public List<Filter> getFilters() {
        return filters;
    }

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

}

package com.dingyu.ChainOfResponsibility;

import java.util.ArrayList;
import java.util.List;

public class Client {
//    private static List<Filter> filters = new ArrayList<Filter>();

    public static void main(String[] args) {
        String s = "<html>，o.o，和谐";
        // 链条1
        FilterChain chain1 = new FilterChain();
        chain1.add(new HTMLFilter());
        // 链条2
        FilterChain chain2 = new FilterChain();
        chain2.add(new HTMLFilter());
        chain2.add(new SensitiveWordFilter());
        // 链条2插到链条1后
        chain1.add(chain2);
        chain1.add(new SymbolFilter());
        s = chain1.doFilter(s);
        System.out.println(s);
        // filters.add(new HTMLFilter());
        // filters.add(new SymbolFilter());
        // filters.add(new SensitiveWordFilter());
        // for (Filter filter : filters) {
        // s = filter.doFilter(s);
        // }
        // System.out.println(s);
    }
}

　　建议debug ， eclipse快捷键

5.　职责链实现双向过滤　　

　　思路类似于递归，建议使用debug一步步调试。

package com.dingyu.ChainOfResponsibility;

/**
 * 过滤器,doFilter处理msg字符串
 * 
 * @author dingyu
 *
 */
public interface Filter {
    // public String doFilter(String msg);
    public void doFilter(Request request, Reponse reponse, FilterChain filterChain);
}

package com.dingyu.ChainOfResponsibility;

/**
 * 处理html符号 测试用的，逻辑不是很严谨
 * 
 * @author dingyu
 *
 */
public class HTMLFilter implements Filter {

    @Override
    public void doFilter(Request request, Reponse reponse, FilterChain filterChain) {
        request.getRequestMsg().replace("<", "[").replace(">", "]");
        filterChain.doFilter(request, reponse, filterChain);
        reponse.setReponseMsg(reponse.getReponseMsg() + "-----HTMLFilter");
    }

    // @Override
    // public String doFilter(String msg) {
    // return msg.replace("<", "[").replace(">", "]");
    // }

}

package com.dingyu.ChainOfResponsibility;

/**
 * 过滤敏感词汇
 * 
 * @author dingyu
 *
 */
public class SensitiveWordFilter implements Filter {

    @Override
    public void doFilter(Request request, Reponse reponse, FilterChain filterChain) {
        request.getRequestMsg().replace("和谐", "/*河蟹*/");
        filterChain.doFilter(request, reponse, filterChain);
        reponse.setReponseMsg(reponse.getReponseMsg() + "-----SensitiveWordFilter");
    }

    // @Override
    // public String doFilter(String msg) {
    // return msg.replace("和谐", "/*河蟹*/");
    // }

}

package com.dingyu.ChainOfResponsibility;

/**
 * 处理符号
 * 
 * @author dingyu
 *
 */
public class SymbolFilter implements Filter {

    @Override
    public void doFilter(Request request, Reponse reponse, FilterChain filterChain) {
        request.getRequestMsg().replace("o.o", "^v^");
        filterChain.doFilter(request, reponse, filterChain);
        reponse.setReponseMsg(reponse.getReponseMsg() + "-----SymbolFilter");
    }

    // @Override
    // public String doFilter(String msg) {
    // return msg.replace("o.o", "^v^");
    // }

}

package com.dingyu.ChainOfResponsibility;

import java.util.ArrayList;
import java.util.List;

/**
 * 
 * @author dingyu
 *
 */
public class FilterChain implements Filter {

    private List<Filter> filters = new ArrayList<Filter>();
    private int index=-1;

    public void add(Filter filter) {
        filters.add(filter);
    }

    public List<Filter> getFilters() {
        return filters;
    }

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

    @Override
    public void doFilter(Request request, Reponse reponse, FilterChain filterChain) {
        if (index == filters.size()-1)
            return;
        index++;
        filters.get(index).doFilter(request, reponse, filterChain);
        
    }

}

package com.dingyu.ChainOfResponsibility;

public class Client03 {
    public static void main(String[] args) {
        Request request = new Request();
        Reponse reponse = new Reponse();
        request.setRequestMsg("<html>，o.o，和谐");
        reponse.setReponseMsg("hahahahaha");
        FilterChain chain = new FilterChain();
        chain.add(new HTMLFilter());
        chain.add(new SensitiveWordFilter());
        chain.add(new SymbolFilter());
        chain.doFilter(request, reponse, chain);
        System.out.println(request.getRequestMsg());
        System.out.println(reponse.getReponseMsg());
    }
}