拦截器模式，是用巧妙的递归实现拦截功能的。

　　类图结构如：

代码实现：

接口：interceptor:

import java.util.List;

public interface Interceptor {
    public List<String> interceptor(TargetInterceptor targetInterceptor);
}

接口Target:
public interface Target {
    public List<String> excute(int count);
}

实现一下
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class TargetInterceptor {
    private List<Interceptor> interceptorList = new ArrayList<Interceptor>();
    private Iterator<Interceptor> interceptors;
    private int count;
    private Target target;

    public List<String> invoke(){
        if(interceptors.hasNext()){
            Interceptor interceptor = interceptors.next();
            return interceptor.interceptor(this);
        }
        return target.excute(count);
    }

    public void addInterceptor(Interceptor interceptor){
        interceptorList.add(interceptor);
        interceptors = interceptorList.iterator();
    }

    public void setCount(int count) {
        this.count = count;
    }

    public void setTarget(Target target) {
        this.target = target;
    }

    public int getCount() {
        return count;
    }

    public Target getTarget() {
        return target;
    }
}

写个日志试试：

import java.util.List;

public class LogInterceptor implements Interceptor{
    @Override
    public List<String> interceptor(TargetInterceptor targetInterceptor) {
        System.out.println("操作在执行之前");
        List<String> data = targetInterceptor.invoke();
        System.out.println("操作在执行之后");
        return data;
    }
}

调用；

import java.util.List;

public class StartMain {
    public static void main(String[] args) {
        TargetInterceptor targetInvocation = new TargetInterceptor();
        targetInvocation.addInterceptor(new LogInterceptor());
        targetInvocation.setCount(20);
        targetInvocation.setTarget(new DataCountTarget());
        List<String> data = targetInvocation.invoke();
        for (String item: data) {
            System.out.println(item);
        }
    }
}

输出：