设计模式学习笔记--拦截过滤器模式

三十一、拦截过滤器模式

拦截过滤器模式(Intercepting Filter Pattern)，主要用于统一接收并过滤客户端的请求，根据过滤器的选择，将请求传送给对应的目标处理程序。

实现

创建过滤器接口IFilter，接口实现类也就是不同的过滤类。创建目标处理程序类Target，还有过滤器组合类FilterChain，过滤器管理类FilterManager以及客户端Client。

• 过滤接口

  IFilter.java

  package patterns.intercepting;
  
  /**
  * Created by lenovo on 2016/12/12 0012.
  * 过滤器接口
  */
  public interface IFilter {
    public void execute(String request);
  }

• 接口实现类

  AuthenticationFilter.java

  package patterns.intercepting;
  
  /**
  * Created by lenovo on 2016/12/12 0012.
  * 过滤器的接口实现类
  */
  public class AuthenticationFilter implements IFilter {
    @Override
    public void execute(String request) {
        System.out.println("授权请求： "+request);
    }
  }

  DebugFilter.java

  package patterns.intercepting;
  
  /**
  * Created by lenovo on 2016/12/12 0012.
  * 过滤器的接口实现类
  */
  public class DebugFilter implements IFilter {
    @Override
    public void execute(String request) {
        System.out.println("调试请求： "+request);
    }
  }

• 目标程序类

  Target.java

  package patterns.intercepting;
  
  /**
  * Created by lenovo on 2016/12/12 0012.
  * 目标程序类
  */
  public class Target {
    public void execute(String request){
        System.out.println("执行处理请求 "+request);
    }
  }

• 过滤器管理类

  FilterManager.java

  package patterns.intercepting;
  
  /**
  * Created by lenovo on 2016/12/12 0012.
  * 过滤器管理类
  */
  public class FilterManager {
    FilterChain filterChain;
  
    public FilterManager(Target target){
        filterChain = new FilterChain();
        filterChain.setTarget(target);
    }
  
    public void setFilter(IFilter filter){
        filterChain.addFilter(filter);
    }
  
    public void filterRequest(String request){
        filterChain.execute(request);
    }
  }

• 组合过滤器类

  FilterChain.java

  package patterns.intercepting;
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
  * Created by lenovo on 2016/12/12 0012.
  * 过滤器组合类
  */
  public class FilterChain {
    private List<IFilter> filters = new ArrayList<>();
    private Target target;
  
    public void addFilter(IFilter filter){
        filters.add(filter);
    }
  
    public void execute(String request){
        for (IFilter filter:filters) {
            filter.execute(request);
        }
        target.execute(request);
    }
  
    public void setTarget(Target target){
        this.target = target;
    }
  }

• 客户端

  Client.java

  package patterns.intercepting;
  
  /**
  * Created by lenovo on 2016/12/12 0012.
  * 客户端类，用于请求
  */
  public class Client {
    FilterManager filterManager;
  
    public void setFilterManager(FilterManager filterManager) {
        this.filterManager = filterManager;
    }
    public void sendRequest(String request){
        filterManager.filterRequest(request);
    }
  }

• 演示

  InterceptingFilterPatternDemo.java

  package patterns.intercepting;
  
  /**
  * Created by lenovo on 2016/12/12 0012.
  * 演示
  */
  public class InterceptingPatternDemo {
    public static void main(String[] args){
        FilterManager filterManager = new FilterManager(new Target());
  
        filterManager.setFilter(new AuthenticationFilter());
        filterManager.setFilter(new DebugFilter());
  
        Client client = new Client();
        client.setFilterManager(filterManager);
        client.sendRequest("Home");
    }
  }

  ​

• 输出

  授权请求： Home
  调试请求： Home
  执行处理请求 Home

  ​