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  • java模式:建造者模式

      我发现很多源码很喜欢用这个模式,比如spring cloud,spring framework。

      建造者模式(Builder)用以构建各种各样的对象,主要功能就是代替对象的构造函数,更加自由化。

      举个栗子,先假设有一个问题,我们需要创建一个学生对象,属性有name,number,class,sex,age,school等属性,如果每一个属性都可以为空,也就是说我们可以只用一个name,也可以用一个school,name,或者一个class,number,或者其他任意的赋值来创建一个学生对象,这时该怎么构造?

      难道我们写6个1个输入的构造函数,15个2个输入的构造函数.......吗?这个时候就需要用到Builder模式了。

      例子借用:https://www.cnblogs.com/malihe/p/6891920.html

    public class Builder {
    
        static class Student{
            String name = null ;
            int number = -1 ;
            String sex = null ;
            int age = -1 ;
            String school = null ;
    
         //构建器,利用构建器作为参数来构建Student对象
            static class StudentBuilder{
                String name = null ;
                int number = -1 ;
                String sex = null ;
                int age = -1 ;
                String school = null ;
                public StudentBuilder setName(String name) {
                    this.name = name;
                    return  this ;
                }
    
                public StudentBuilder setNumber(int number) {
                    this.number = number;
                    return  this ;
                }
    
                public StudentBuilder setSex(String sex) {
                    this.sex = sex;
                    return  this ;
                }
    
                public StudentBuilder setAge(int age) {
                    this.age = age;
                    return  this ;
                }
    
                public StudentBuilder setSchool(String school) {
                    this.school = school;
                    return  this ;
                }
                public Student build() {
                    return new Student(this);
                }
            }
    
            public Student(StudentBuilder builder){
                this.age = builder.age;
                this.name = builder.name;
                this.number = builder.number;
                this.school = builder.school ;
                this.sex = builder.sex ;
            }
        }
    
        public static void main( String[] args ){
            Student a = new Student.StudentBuilder().setAge(13).setName("LiHua").build();
            Student b = new Student.StudentBuilder().setSchool("sc").setSex("Male").setName("ZhangSan").build();
        }
    }
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  • 原文地址:https://www.cnblogs.com/garfieldcgf/p/10291164.html
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