徒手撸设计模式迭代器模式

概念

迭代器模式（Iterator Pattern）是 Java 和 .Net 编程环境中非常常用的设计模式。这种模式用于顺序访问集合对象的元素，不需要知道集合对象的底层表示。

迭代器模式属于行为型模式。

参考链接: https://www.runoob.com/design-pattern/iterator-pattern.html

代码案例

设计迭代器接口,有两个方法hasNext,next

/**
 * 迭代器类
 */
public interface Iterator {
    boolean hasNext();
    Object next();
}

容器接口,获取迭代器

/**
 * 容器类
 */
public interface Container {
    Iterator getIterator();
}

集合容器,内部类实现迭代器功能

/**
 * 车子集合,提供迭代器功能
 */
@Slf4j
public class CarsList implements Container {
    private String[] carsArr;

    public CarsList(String[] carsArr) {
        this.carsArr = carsArr;
    }

    @Override
    public Iterator getIterator() {
        return new CarsIterator();
    }

    private class CarsIterator implements  Iterator{

        int index;
        @Override
        public boolean hasNext() {
            if (index<carsArr.length){
                log.info("carsArr has next ");
                return true;
            }
            return false;
        }

        @Override
        public Object next() {
            if (this.hasNext()){
                String perCars = carsArr[index++];
                log.info("current cars is : {}",perCars);
                return perCars;
            }
            return null;
        }
    }
}

测试主类

/**
 * 设计模式控制器
 */
@RestController
@RequestMapping("/designPattern")
@Slf4j
public class DesignController {
    @PostMapping("/iterator")
    public ResponseModel iterator(@RequestBody String[] carsArr) {
        log.info("iterator   ---- start ");
        List list= new ArrayList();
        CarsList carsList = new CarsList(carsArr);
        Iterator iterator = carsList.getIterator();
        while (iterator.hasNext()){
            String perCars = (String) iterator.next();
            list.add(perCars);
        }
        log.info("iterator   ---- end ");
        return new ResponseModel("迭代器模式完成", 200, list);
    }
}

测试案例

2022-06-30 00:49:12.128 INFO  iterator   ---- start  【http-nio-8081-exec-1】【DesignController:75】
2022-06-30 00:49:12.133 INFO  carsArr has next  【http-nio-8081-exec-1】【CarsList:29】
2022-06-30 00:49:12.133 INFO  carsArr has next  【http-nio-8081-exec-1】【CarsList:29】
2022-06-30 00:49:12.134 INFO  current cars is : BMW 【http-nio-8081-exec-1】【CarsList:39】
2022-06-30 00:49:12.134 INFO  carsArr has next  【http-nio-8081-exec-1】【CarsList:29】
2022-06-30 00:49:12.134 INFO  carsArr has next  【http-nio-8081-exec-1】【CarsList:29】
2022-06-30 00:49:12.134 INFO  current cars is : Giant 【http-nio-8081-exec-1】【CarsList:39】
2022-06-30 00:49:12.134 INFO  carsArr has next  【http-nio-8081-exec-1】【CarsList:29】
2022-06-30 00:49:12.135 INFO  carsArr has next  【http-nio-8081-exec-1】【CarsList:29】
2022-06-30 00:49:12.138 INFO  current cars is : Benz 【http-nio-8081-exec-1】【CarsList:39】
2022-06-30 00:49:12.138 INFO  carsArr has next  【http-nio-8081-exec-1】【CarsList:29】
2022-06-30 00:49:12.138 INFO  carsArr has next  【http-nio-8081-exec-1】【CarsList:29】
2022-06-30 00:49:12.139 INFO  current cars is : Merida 【http-nio-8081-exec-1】【CarsList:39】
2022-06-30 00:49:12.139 INFO  iterator   ---- end  【http-nio-8081-exec-1】【DesignController:83】