23種設計模式之過濾模式

/**
 * 1.模式定義：
 *   過濾器(Filter Pattern)又稱為標準模式(Criteria Pattern)是一種設計模式,這種模式允許開發人員使用不同的標準來過濾一組對象，
 *   通過預算邏輯以解耦的方式將他們聯繫起來。這種類型的設計模式屬於結構模型,說白了,就是按條件篩選一組對象出來。
 *   目的:使用不同標準來過濾一組對象
 *   實現:制定不同的規則來實現過濾,然後對過濾結果進行分組。
 * 2.組成角色：
 *   1)抽象過濾器角色(AbstractFilter)：負責定義過濾器的實現介面,具體的實現還要具體過濾器角色去參與，客戶端可以調用抽象過濾器角色中定義好
 *     的方法，將 客戶端的所有請求委派到具體的實現類去，從而讓實現類去處理。
 *   2)ConcreteFilter(具體過濾角色):該角色負責具體篩選規則的邏輯實現，最後再返回一個過濾後的數據集合，標準的過濾器只對數據做過濾,當然也
 *     可以對集合中的數據做某項處理,再將處理後的集合返回。
 *   3)Subject(被過濾的主體角色):一個軟體系統中可以有一個或多個目標角色,在具體過濾器角色中對指定的目標進行處理。
 * 3.過濾器延伸：
 *   過濾器鏈：攜帶多個過濾器,並且可以以自定義順序執行他們。
 *   過濾器管理角色：負責管理過濾器和過濾器鏈。
 * 4.應用場景：
 *   垃圾桶分類
 * 5.總結：
 *   1)可插拔：過濾器的設計概念要求其實支持可插拔設計的。
 *   2)有序性:過濾器是被設計為一組組的過濾裝置,要實現數據過濾,就必須有序性要求.
 *   3)過濾器的獨立性:每種過濾器必須是獨立的實體,其狀態不受其它過濾器的影響,每個過濾器都有自己獨立的數據輸入輸出介面,只要各個過濾器之間
 *     傳送的數據遵守共同的規約就可以相連接。
 */

/*
 * 垃圾類，被過濾的主題角色
 */
public class Rubbish {
    private String name; //垃圾名稱
    private boolean isHarm; //是否有害垃圾
    private boolean isRecycled; //是否可回收
    private boolean isDry; //是否乾垃圾
    private boolean isWet; //是否濕垃圾
    
    public Rubbish(String name, boolean isHarm, boolean isRecycled, boolean isDry, boolean isWet) {
        this.name = name;
        this.isHarm = isHarm;
        this.isRecycled = isRecycled;
        this.isDry = isDry;
        this.isWet = isWet;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public boolean isHarm() {
        return isHarm;
    }
    public void setHarm(boolean isHarm) {
        this.isHarm = isHarm;
    }
    public boolean isRecycled() {
        return isRecycled;
    }
    public void setRecycled(boolean isRecycled) {
        this.isRecycled = isRecycled;
    }
    public boolean isDry() {
        return isDry;
    }
    public void setDry(boolean isDry) {
        this.isDry = isDry;
    }
    public boolean isWet() {
        return isWet;
    }
    public void setWet(boolean isWet) {
        this.isWet = isWet;
    }
}

/*
 * 過濾標準的介面，即抽象過濾角色
 */
public interface Criteria {
    //定義過濾的標準
    List<Rubbish> rubbishFilter(List<Rubbish> rubbishs);

}

/*
 * 實現Criteria介面的實體類
 */
//乾垃圾
public class DryRubbishCriteria implements Criteria {

    @Override
    public List<Rubbish> rubbishFilter(List<Rubbish> rubbishs) {
        List<Rubbish> rubbishList=new ArrayList<Rubbish>();
        for(Rubbish rubbish:rubbishs) {
            //這裡只過濾出所有乾垃圾
            if (rubbish.isDry()) {
                rubbishList.add(rubbish);
            }
        }
        return rubbishList;
    }

}

//有害垃圾
public class HarmfulRubbishCriteria implements Criteria {

    @Override
    public List<Rubbish> rubbishFilter(List<Rubbish> rubbishs) {
        List<Rubbish> rubbishList=new ArrayList<Rubbish>();
        for(Rubbish rubbish:rubbishs) {
            //這裡只過濾出所有乾垃圾
            if (rubbish.isHarm()) {
                rubbishList.add(rubbish);
            }
        }
        return rubbishList;
    }

}

//可回收垃圾
public class RecycledRubbishCriteria implements Criteria{

    @Override
    public List<Rubbish> rubbishFilter(List<Rubbish> rubbishs) {
        List<Rubbish> rubbishList=new ArrayList<Rubbish>();
        for(Rubbish rubbish:rubbishs) {
            //這裡只過濾出所有乾垃圾
            if (rubbish.isRecycled()) {
                rubbishList.add(rubbish);
            }
        }
        return rubbishList;
    }

}

//濕垃圾
public class WetRubbishCriteria implements Criteria{

    @Override
    public List<Rubbish> rubbishFilter(List<Rubbish> rubbishs) {
        List<Rubbish> rubbishList=new ArrayList<Rubbish>();
        for(Rubbish rubbish:rubbishs) {
            //這裡只過濾出所有乾垃圾
            if (rubbish.isWet()) {
                rubbishList.add(rubbish);
            }
        }
        return rubbishList;
    }

}

測試結果如下：

//使用不同的標準(Criteria)來過濾Rubbish對象的列表
public class Main {
    public static void main(String[] args) {
        //原始數據集合
        List<Rubbish> rubbishList = new ArrayList<Rubbish>();
        rubbishList.add(new Rubbish("果殼", false, false, true, false));
        rubbishList.add(new Rubbish("陶瓷", false, false, true, false));
        rubbishList.add(new Rubbish("菜根菜葉", false, false, false, true));
        rubbishList.add(new Rubbish("果皮", false, false, false, true));
        rubbishList.add(new Rubbish("電池", true, false, false, false));
        rubbishList.add(new Rubbish("水銀溫度計", true, false, false, false));
        rubbishList.add(new Rubbish("燈泡", true, false, false, false));
        rubbishList.add(new Rubbish("廢紙塑料", false, true,false, false));
        rubbishList.add(new Rubbish("金屬和布料", false, true, false, false));
        //四種不同的過濾標準
        Criteria dryRubbishCriteria=new DryRubbishCriteria();
        Criteria wetRubbishCriteria=new WetRubbishCriteria();
        Criteria harRubbishCriteria=new HarmfulRubbishCriteria();
        Criteria recycledRubbishCriteria=new RecycledRubbishCriteria();
        
        System.out.println("乾垃圾:");
        printRubbishes(dryRubbishCriteria.rubbishFilter(rubbishList));
        System.out.println("濕垃圾:");
        printRubbishes(wetRubbishCriteria.rubbishFilter(rubbishList));
        System.out.println("有害垃圾:");
        printRubbishes(harRubbishCriteria.rubbishFilter(rubbishList));
        System.out.println("可回收垃圾:");
        printRubbishes(recycledRubbishCriteria.rubbishFilter(rubbishList));
        
    }
    private static void printRubbishes(List<Rubbish> rubbishs) {
        for(Rubbish rubbish:rubbishs) {
            System.out.println(rubbish.getName());
        }
        
    }

}

乾垃圾:
果殼
陶瓷
濕垃圾:
菜根菜葉
果皮
有害垃圾:
電池
水銀溫度計
燈泡
可回收垃圾:
廢紙塑料
金屬和布