構建者設計模式：一個複雜物件的構建獨立於它的組成部分。

下面以一個內部類的方式解釋這種建立者設計模式：
User類：

package com.xiaofeng;

/**
 * Project :Danli
 * Created : XiaoFeng1015
 * Date : 2016/7/30
 */
// 構件者模式
public class User {

        private String password;
        private String username;
        private String nickName;
        private int
 
 age;
        private String email;


    public User(String password, String username) {
        this.password = password;
        this.username = username;
    }

    // 構建者模式，私有的構造方法，在內部類中可以使用
    private User(String password, String username, String nickName, int age, String email) {
            this
 
.password = password;
            this.username = username;
            this.nickName = nickName;
            this.age = age;
            this.email = email;
        }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public
 
 String getUserName() {
        return username;
    }

    public void setUserName(String userword) {
        this.username = userword;
    }

    public String getNickName() {
        return nickName;
    }

    public void setNickName(String nickName) {
        this.nickName = nickName;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    // 靜態內部類
    // 使用方式，和普通類一樣
    //  1、靜態內部類可以使用外部類中所有的靜態屬性和方法。包括私有的；
    //  2、靜態內部類還可以使用外部類中所有的構造方法。包括私有的。


    public static class Builder {
        private String password;
        private String username;
        private String nickName;
        private int age;
        private String email;


        public Builder(String password, String username) {
            this.password = password;
            this.username = username;
        }

        // set方法返回一個Builder的物件，用來以後對User物件的屬性的擴充套件。
        public Builder setPassword(String password) {
            this.password = password;
            return this;
        }

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

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

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

        public User build() {
            return new User(password, username, nickName, age, email);
        }
    }
}

測試類Test：

package com.xiaofeng;

import com.xiaofeng.User.Builder;
/**
 * Project :Danli
 * Created : XiaoFeng1015
 * Date : 2016/7/30
 */
public class Test02 {
    public static void main(String[] args) {

        User user = new Builder("user", "123456").setEmail("[email protected]").setAge(10).build();
        System.out.println(user.getUserName());
        System.out.println(user.getNickName());
        System.out.println(user.getEmail());
    }


}

執行結果：