当多个类继承单个抽象类时使用生成器模式

Question

我正在用两个实体构建web应用程序：

1. 漫画-id、标题、发行日期、封面id、流派、作者、卷等

这两个类继承自抽象类书。Book类将为这两个类提供公共变量：id、title、releaseDate、coverID；

我正在使用Pattern Builder创建漫画和体积对象。但当我试图设置描述时，我得到了以下错误：

        Manga manga = (Manga) new Manga.Builder().setID(id)
                                     .setTitle(title)
                                     .setCoverID(id)
                                     .setDescription() //Cannot resolve method 'setDescription' in 'Builder'
                                     .build();

图书类：

公开摘要类书籍

public final Long id;
public final String title;

protected Book(final Builder<T> builder) {
    this.id = builder.id;
    this.title = builder.title;
}

public abstract static class Builder<T> {
    private Long id;
    private String title;

    public Builder<T> setID(Long id) {
        this.id = id;
        return this;
    }

    public Builder<T> setTitle(String title) {
        this.title = title;
        return this;
    }

    public abstract T build();
}

我的漫画课：

public class Manga extends Book<Manga> {

private final String description;

protected Manga(Builder builder) {
    super(builder);
    this.description = builder.description;
}

public static class Builder extends Book.Builder<Manga> {
    
    private String description;

    public Builder setDescription(String description) {
        this.description = description;
        return this;
    }

    @Override
    public Manga build() {
        return new Manga(this);
    }
}

或者有更好的解决方案吗？

谢谢

Answer 1

这应该是可行的：

package de.dwosch;

public abstract class Book {

    public final Long id;
    public final String title;

    protected Book(final Builder<?> builder) {
        this.id = builder.id;
        this.title = builder.title;
    }

    public abstract static class Builder<T extends Builder<T>> {
        private Long id;
        private String title;

        public T id(Long id) {
            this.id = id;
            return me();
        }

        public T title(String title) {
            this.title = title;
            return me();
        }

        public abstract T me();
        public abstract Book build();
    }
}

然后呢

package de.dwosch;

public class Manga extends Book {

    private final String description;

    protected Manga(Builder builder) {
        super(builder);
        this.description = builder.description;
    }

    public static class Builder extends Book.Builder<Builder> {

        private String description;

        public Builder description(String description) {
            this.description = description;
            return this;
        }

        @Override
        public Builder me() {
            return this;
        }

        @Override
        public Manga build() {
            return new Manga(this);
        }
    }
}

用法

    Manga manga = new Manga.Builder().description("test")
            .title("title")
            .build();

我已经多次实现了这个模式。约书亚·布洛赫（Joshua Bloch）在他的书《有效的Java》（great book btw）中写到了这一点。

如果你需要进一步的信息，请告诉我。

顺便说一句：没有set的个人偏好设置方法。看起来更干净：）