装饰者模式【结构模式】

public class Decorator {
/**
* 装饰者模式：
* Attach additional responsibility to an object dynamically keeping the same interface.
* Decorators provide a flexible alternative to subclassing for extending functionality.
* 将额外的责任附加到一个动态保持相同接口的对象上，装饰者提供一种灵活的选择将扩展功能子类化。
*/
@Test
public void all() {
final PlainMaker plainMaker = PlainMaker.builder().build();
final String info = "hello world";
String make = plainMaker.make(info);
assertEquals(make,info);

final String title = "重大新闻";
    // 给新闻增加标题
    final TitleMaker titleMaker = TitleMaker.builder()
            .newsMaker(plainMaker)
            .title(title).build();
    make = titleMaker.make(info);
    assertEquals(String.join("\r\n",title,info),make);

    final String copyRight = "版权所有 15505883728";
    // 给新闻增加版权
    final copyRightMaker copyRightMaker = copyRightMaker.builder()
            .newsMaker(titleMaker)
            .copyRight(copyRight)
            .build();
    make = copyRightMaker.make(info);
    assertEquals(String.join("\r\n",info,copyRight),make);
}

}

/**

• 1）定义允许执行装饰的功能接口，也可以是抽象类。
  */
  interface NewsMaker {
  String make(String info);
  }

/**

• 2）具体实现功能的实例类
  */
  @Builder
  class PlainMaker implements NewsMaker {
  @Override
  public String make(String info) {
  return info;
  }
  }

/**

• 3）对功能进行装饰的装饰类
  */
  @Builder
  class TitleMaker implements NewsMaker {
  private final NewsMaker newsMaker;
  private final String title;

  @Override
  public String make(String info) {
  return title + "\r\n" + newsMaker.make(info);
  }
  }

/**

• 4）对功能进行装饰的装饰类
  */
  @Builder
  class copyRightMaker implements NewsMaker {
  private final NewsMaker newsMaker;
  private final String copyRight;

  @Override public String make(String info) { return newsMaker.make(info) + "\r\n" + copyRight; } }