Template Pattern

📌 처리에 대한 로직은 정해져 있을때, 이 로직을 구성하는 각각의 세부항목에 대한 처리들을 다르게 정의하고자 할때 사용할 수 있는 패턴

템플릿을(동일한 부분) 작성한다

//Article.java
public class Article {
    private String title;
    private ArrayList<String> content;
    private String footer;
 
    public Article(String title, ArrayList<String> content, String footer) {
        this.title = title;
        this.content = content;
        this.footer = footer;
    }

    public String getTitle() {
        return title;
    }

    public ArrayList<String> getContent() {
        return content;
    }

    public String getFooter() {
        return this.footer;
    }
}

//DisplayArticleTemplate.java
public abstract class DisplayArticleTemplate {
    protected abstract void title();
    protected abstract void content();
    protected abstract void footer();

    protected Article article;
    public DisplayArticleTemplate(Article article) {
        this.article = article;
    }

    public final void display() {
        title();
        content();
        footer();
    }
}

다르게 동작하는 세부항목 로직을 작성한다

//SimpleArcticle.java
public class SimpleArcticle extends DisplayArticleTemplate {
    public SimpleArcticle(Article article) {
        super(article);
    }
    @Override
    protected void title() {
        System.out.println(article.getTitle());
    }
    @Override
    protected void content() {
        ArrayList<String> content = article.getContent();
        int cntLines = content.size();
        for(int i=0; i<cntLines; i++) {
            System.out.println(content.get(i));
        }
    }
    @Override
    protected void footer() {
        System.out.println(article.getFooter());
    }
}

//CaptionArticle.java
public class CaptionArticle extends DisplayArticleTemplate {
    public CaptionArticle(Article article) {
        super(article);
    }
    @Override
    protected void title() {
        System.out.println("TITLE: " + article.getTitle());
    }
    @Override
    protected void content() {
        System.out.println("CONTENT:");
    
        ArrayList<String> content = article.getContent();
        int cntLines = content.size();
        for(int i=0; i<cntLines; i++) {
            System.out.println("    " + content.get(i));
        }
    }
    @Override
    protected void footer() {
        System.out.println("FOOTER: " + article.getFooter());
    }
}

하나의 템플릿으로 다르게 동작하는 것을 확인할 수 있다.

//Main.java
public class Main {
    public static void main(String[] args) {
        String title = "GIS, powerful tool";
    
        ArrayList<String> content = new ArrayList<String>();
        content.add("GIS is a geographic information system.");
        content.add("It is base on real spatial data.");
        content.add("It provides analyzing spatial and geographic data");
 
        String footer = "2020.10.08, written by Dip2K";
       
        Article article = new Article(title, content, footer);
       
        System.out.println("[CASE-1]");
        DisplayArticleTemplate style1 = new SimpleArcticle(article);
        style1.display();
     
        System.out.println();
     
        System.out.println("[CASE-2]");
        DisplayArticleTemplate style2 = new CaptionArticle(article);
        style2.display();
    }
}

🙌 전체적으로 동일하면서 부분적으로 다른 구문의 코드중복을 최소화할 수 있다.

#행위패턴의 하나

참고