创建型-建造者模式

前言

public class Student {
    int id;
    int age;
    String name;
    String gender; 
    String profession;
    List<String> awards;

    public Student(int id, int age, String name, String gender, String profession, List<String> awards) {
        this.id = id;
        this.age = age;
        this.name = name;
        this.gender = gender; 
        this.profession = profession;
        this.awards = awards;
    }

学生类的属性非常多，导致构造函数，也非常多，如果我们通过new的方式创建很容易填错参数位置。

public class Main {
    public static void main(String[] args) {
        List<String> awards = Arrays.asList("LPL 春季赛冠军","上海Major冠军");
        Student student = new Student(1, 18, "小明", "男", "计算机科学与技术", awards);
        System.out.println(student);
    }
}

建造者模式

public class Student {
    int id;
    int age;
    String name;
    String gender; 
    String profession;
    List<String> awards;

    private Student(int id, int age, String name, String gender, String profession, List<String> awards) {
        this.id = id;
        this.age = age;
        this.name = name;
        this.gender = gender; 
        this.profession = profession;
        this.awards = awards;
    }

    public static StudentBuilder builder() {  //通过builder直接获取建造者
        return new StudentBuilder();
    }

    public static class StudentBuilder {
        int id;
        int age;
        String name;
        String gender;
        String profession;
        List<String> awards;

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

        public StudentBuilder age(int age) {
            this.age = age;
            return this;
        }

        public StudentBuilder name(String name) {
            this.name = name;
            return this;
        }

        public StudentBuilder gender(String gender) {
            this.gender = gender;
            return this;
        }

        public StudentBuilder profession(String profession) {
            this.profession = profession;
            return this;
        }

        public StudentBuilder awards(List<String> awards) {
            this.awards = awards;
            return this;
        }

        public Student build() {
            return new Student(id, age, name, gender, profession, awards);
        }
    }
}

public class Main {
    public static void main(String[] args) {
        Student.StudentBuilder builder = Student.builder();
        List<String> awards = Arrays.asList("LPL 春季赛冠军", "上海Major冠军");
        builder.id(1).name("John Doe").gender("Male").awards(awards).profession("").build();
    }
}

建造者模式提供了一种清晰、灵活且易于维护的方式来构建对象，尤其适用于具有多个参数和复杂构建逻辑的情况。