拦截过滤模式

拦截过滤器模式（Intercepting Filter Pattern）用于对应用程序的请求或响应做一些预处理/后处理。定义过滤器，并在把请求传给实际目标应用程序之前应用在请求上。过滤器可以做认证/授权/记录日志，或者跟踪请求，然后把请求传给相应的处理程序。以下是这种设计模式的实体。

  • 过滤器（Filter）

过滤器在请求处理程序执行请求之前或之后，执行某些任务。

  • 过滤器链（Filter Chain）

过滤器链带有多个过滤器，并在 Target 上按照定义的顺序执行这些过滤器。

实际案例

类信息概览：

类名 说明
Main.java 方法的总入口
FilterChain.java 过滤器链
ValidFilter.java 校验过滤
AuthFilter.java 验证过滤
Filter.java 过滤接口

定义

  • FilterChain.java
/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * Copyright (c) 2012-2018. houbinbini Inc.
 * design-pattern All rights reserved.
 */

package com.ryo.design.pattern.note.interceptingFilter;

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

/**
 * <p> </p>
 *
 * <pre> Created: 2018/5/29 下午5:24  </pre>
 * <pre> Project: design-pattern  </pre>
 *
 * @author houbinbin
 * @version 1.0
 * @since JDK 1.7
 */
public class FilterChain implements Filter {

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

    public FilterChain addFilter(Filter filter) {
        filterList.add(filter);
        return this;
    }


    @Override
    public Filter filter(String info) {
        for(Filter filter : this.filterList) {
            filter.filter(info);
        }
        return this;
    }

}
  • ValidFilter.java
/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * Copyright (c) 2012-2018. houbinbini Inc.
 * design-pattern All rights reserved.
 */

package com.ryo.design.pattern.note.interceptingFilter;

/**
 * <p> </p>
 *
 * <pre> Created: 2018/5/29 下午5:22  </pre>
 * <pre> Project: design-pattern  </pre>
 *
 * @author houbinbin
 * @version 1.0
 * @since JDK 1.7
 */
public class ValidFilter implements Filter {

    @Override
    public Filter filter(String info) {
        System.out.println("[Valid]: "+info);
        return this;
    }

}
  • AuthFilter.java
/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * Copyright (c) 2012-2018. houbinbini Inc.
 * design-pattern All rights reserved.
 */

package com.ryo.design.pattern.note.interceptingFilter;

/**
 * <p> 权限过滤器 </p>
 *
 * <pre> Created: 2018/5/29 下午5:22  </pre>
 * <pre> Project: design-pattern  </pre>
 *
 * @author houbinbin
 * @version 1.0
 * @since JDK 1.7
 */
public class AuthFilter implements Filter {

    @Override
    public Filter filter(String info) {
        System.out.println("[Auth]: "+info);
        return this;
    }

}
  • Filter.java
/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * Copyright (c) 2012-2018. houbinbini Inc.
 * design-pattern All rights reserved.
 */

package com.ryo.design.pattern.note.interceptingFilter;

/**
 * <p> </p>
 *
 * <pre> Created: 2018/5/29 下午5:22  </pre>
 * <pre> Project: design-pattern  </pre>
 *
 * @author houbinbin
 * @version 1.0
 * @since JDK 1.7
 */
public interface Filter {

    /**
     * 执行过滤信息
     * @param info 原始信息
     * @return 过滤器本身
     */
    Filter filter(final String info);

}

测试

  • Main.java
/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * Copyright (c) 2012-2018. houbinbini Inc.
 * design-pattern All rights reserved.
 */

package com.ryo.design.pattern.note.interceptingFilter;

/**
 * <p> </p>
 *
 * <pre> Created: 2018/5/29 下午5:20  </pre>
 * <pre> Project: design-pattern  </pre>
 *
 * @author houbinbin
 * @version 1.0
 * @since JDK 1.7
 */
public class Main {

    public static void main(String[] args) {
        FilterChain filterChain = new FilterChain();
        filterChain.addFilter(new AuthFilter())
                .addFilter(new ValidFilter());
        filterChain.filter("filtered info");
    }

}
  • 测试结果
[Auth]: filtered info
[Valid]: filtered info

实现方式

UML & Code

UML

UML 图示如下

Code

代码地址

拦截过滤模式

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