JAVA 언어로 배우는 디자인 패턴 입문

Iterator Pattern

public class Book {
    private String name;

    public Book(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }
}

public class BookShelf implements Iterable<Book> {
    private List<Book> books;

    public BookShelf(int initialsize) {
        this.books = new ArrayList<>(initialsize);
    }

    public Book getBookAt(int index) {
        return books.get(index);
    }

    public void appendBook(Book book) {
        books.add(book);
    }

    public int getLength() {
        return books.size();
    }

    @Override
    public Iterator<Book> iterator() {
        return new BookShelfIterator(this);
    }
}

public class BookShelfIterator implements Iterator<Book> {
    private BookShelf bookShelf;
    private int index;

    public BookShelfIterator(BookShelf bookShelf) {
        this.bookShelf = bookShelf;
        this.index = 0;
    }

    @Override
    public boolean hasNext() {
        if (index < bookShelf.getLength()) {
            return true;
        } else {
            return false;
        }
    }

    @Override
    public Book next() {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        Book book = bookShelf.getBookAt(index);
        index++;
        return book;
    }
}

Adapter Pattern

public class Banner {
    private String string;

    public Banner(String string) {
        this.string = string;
    }

    public void showWithParen() {
        System.out.println("(" + string + ")");
    }

    public void showWithAster() {
        System.out.println("*" + string + "*");
    }
}

public abstract class Print {
    public abstract void printWeak();
    public abstract void printStrong();
}

public class PrintBanner extends Print {
    private Banner banner;

    public PrintBanner(String string) {
        this.banner = new Banner(string);
    }

    @Override
    public void printWeak() {
        banner.showWithParen();
    }

    @Override
    public void printStrong() {
        banner.showWithAster();
    }
}

Template Method

public interface AbstractDisplay {
    public void open();
    public void print();
    public void close();

    public default void display() {
        open();
        for (int i = 0; i < 5; i++) {
            print();
        }
        close();
    }
}

public class CharDisplay implements AbstractDisplay {
    private char ch; // 표시해야 하는 문자 

    // 생성자 
    public CharDisplay(char ch) {
        this.ch = ch;
    }

    @Override
    public void open() {
        // 시작 문자열 "<<"를 표시한다 
        System.out.print("<<");
    }

    @Override
    public void print() {
        // 필드에 저장해 둔 문자를 1회 표시한다
        System.out.print(ch);
    }

    @Override
    public void close() {
        // 종료 문자열 ">>"를 표시한다 
        System.out.println(">>");
    }
}

public class StringDisplay implements AbstractDisplay {
    private String string;  // 표시해야 하는 문자열 
    private int width;      // 문자열의 길이

    // 생성자 
    public StringDisplay(String string) {
        this.string = string;
        this.width = string.length();
    }

    @Override
    public void open() {
        printLine();
    }

    @Override
    public void print() {
        System.out.println("|" + string + "|");
    }

    @Override
    public void close() {
        printLine();
    }

    //  open과 close에서 호출되어 "+----+" 문자열을 표시하는 메소드
    private void printLine() {
        System.out.print("+");
        for (int i = 0; i < width; i++) {
            System.out.print("-");
        }
        System.out.println("+");
    }
}

Mvitimin / Microservices_study

JAVA 언어로 배우는 디자인 패턴 입문 #16

Iterator Pattern

Adapter Pattern

Template Method