使用建造者模式创建一个流式API

使用建造者模式创建一个流式API

1. 代码如下：

   package com.zengpinlin.aopdemo.model;
   
   
   public class User {
     private String userName;
     private String age;
     private String password;
   
     /**
      * 私有构造参数
      *
      * @param build
      */
     private User(Build build) {
       age = build.age;
       password = build.password;
       userName = build.userName;
     }
   
     public static void main(String[] args) {
       User user = new Build()
               .age("test")
               .password("test")
               .userName("test")
               .build();
       System.out.println("user = " + user);
     }
   
     @Override
     public String toString() {
       return "User{"
           + "userName='"
           + userName
           + '\''
           + ", age='"
           + age
           + '\''
           + ", password='"
           + password
           + '\''
           + '}';
     }
   
     public static class Build {
       private String userName;
       private String age;
       private String password;
   
       public Build() {}
   
       public Build(String userName, String age, String password) {
         this.age = age;
         this.userName = userName;
         this.password = password;
       }
   
       public Build userName(String userName) {
         this.userName = userName;
         return this;
       }
   
       public Build age(String age) {
         this.age = age;
         return this;
       }
   
       public Build password(String password) {
         this.password = password;
         return this;
       }
   
       public User build() {
         return new User(this);
       }
     }
   }

   说明：

   1.链式的原理也很简单，我的理解就是，内部中每次赋完会返回当前对象，这样就可以进行下次的调用（可以想象成每次我们创一个对象，然后通过对象的引用，进行赋值操作）
   

   2.如果一类有很多属性，可以写成链式调用，这样可以减少客户端的setXX操作，提供代码可读性。