在swagger，shiro等原始碼中構建者模式使用非常普及，以例子驅動

package test;

/**
 * 構建者模式
 *
 * 避免getter，setter程式碼冗雜
 * 避免參數條件配置數量導致的含參構造程式碼冗雜
 * @author Nfen.Z
 */
public class Post {

    private int id;
    private String title;
    private String content;
    private String author;

    public Post(Builder builder) {
        this.id = builder.id;
        this.title = builder.title;
        this.content = builder.content;
        this.author = builder.author;
    }

    @Override
    public String toString() {
        return "Post{" +
                "id=" + id +
                ", title='" + title + '\'' +
                ", content='" + content + '\'' +
                ", author='" + author + '\'' +
                '}';
    }

    // 只要內部類key被宣告為靜態，此處宣告為靜態僅僅為了通過 A.B方式來呼叫
    static class Builder {

        private int id;
        private String title;
        private String content;
        private String author;

        public Builder id(int id) {
            this.id = id;
            return this;
        }

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

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

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

        public Post build() {
            return new Post(this);
        }

    }

    public static void main(String[] args) {
        Post test = new Post.Builder().id(2).content("測試").build();
        System.out.println(test);
    }

}

 

結果如下：

靜態內部類和非靜態內部類區別

• 靜態內部類只能夠訪問外部類的靜態成員,而非靜態內部類則可以訪問外部類的所有成員(方法，屬性)
• 靜態內部類和非靜態內部類在建立時有區別

//假設類A有靜態內部類B和非靜態內部類C，建立B和C的區別為：

A a=new A(); 
A.B b=new A.B(); 
A.C c=a.new C();