JAVA设计模式之简单粗暴学建造者模式

将一个复杂对象的构建和它的表示分离，使得同样的构建过程可以创建不同的表示。

建造者有以下角色：

• 导演类：负责安排已有模块的安装顺序，最后通知建造者开始建造。
• 建造者：抽象Builder类，用于规范产品的组建。
• 具体建造者：实现抽象Builder类的所有方法，并返回建造好的对象。
• 产品类。

简单示例

1、产品类

public class MobilePhone {

    //手机屏幕
    private String screen;
    //电池
    private String battery;
    //话筒
    private String microphone;
    //听筒
    private String phoneReceiver;
    //机身
    private String phoneBody;

    public String getScreen() {
        return screen;
    }

    public void setScreen(String screen) {
        this.screen = screen;
    }

    public String getBattery() {
        return battery;
    }

    public void setBattery(String battery) {
        this.battery = battery;
    }

    public String getMicrophone() {
        return microphone;
    }

    public void setMicrophone(String microphone) {
        this.microphone = microphone;
    }

    public String getPhoneReceiver() {
        return phoneReceiver;
    }

    public void setPhoneReceiver(String phoneReceiver) {
        this.phoneReceiver = phoneReceiver;
    }

    public String getPhoneBody() {
        return phoneBody;
    }

    public void setPhoneBody(String phoneBody) {
        this.phoneBody = phoneBody;
    }

    @Override
    public String toString() {
        return "MobilePhone{" +
                "screen='" + screen + '\'' +
                ", battery='" + battery + '\'' +
                ", microphone='" + microphone + '\'' +
                ", phoneReceiver='" + phoneReceiver + '\'' +
                ", phoneBody='" + phoneBody + '\'' +
                '}';
    }
}

2、抽象建造者

public interface IBuildMobilePhoneBuilder {
    /**
     * 建造手机屏幕
     */
    void buildScreen();

    /**
     * 建造手机电池
     */
    void buildBattery();

    /**
     * 建造手机听筒
     */
    void buildMicrophone();

    /**
     * 建造手机话筒
     */
    void buildPhoneReceiver();

    /**
     * 建造手机机身
     */
    void buildPhoneBody();

    MobilePhone build();
}

3、具体建造者

public class IPhoneXBuilder implements IBuildMobilePhoneBuilder {
    private MobilePhone mobilePhone;

    public IPhoneXBuilder(){
        mobilePhone =  new MobilePhone();
    }

    /**
     * 建造手机屏幕
     */
    @Override
    public void buildScreen() {
        mobilePhone.setScreen("OLED显示屏");
    }

    /**
     * 建造手机电池
     */
    @Override
    public void buildBattery() {
        mobilePhone.setBattery("2700mAh电池容量");
    }

    /**
     * 建造手机听筒
     */
    @Override
    public void buildMicrophone() {
        mobilePhone.setMicrophone("听筒");
    }

    /**
     * 建造手机话筒
     */
    @Override
    public void buildPhoneReceiver() {
        mobilePhone.setPhoneReceiver("话筒");
    }

    /**
     * 建造手机机身
     */
    @Override
    public void buildPhoneBody() {
        mobilePhone.setPhoneBody("iphoneX机身");
    }


    /**
     * 创建手机
     * @return
     */
    public MobilePhone build(){
        return mobilePhone;
    }
}

4、导演类

public class Director {
    /**
     * 建造一部手机
     * @param buildPhone
     * @return
     */
    public MobilePhone createMobilePhone(IBuildMobilePhoneBuilder buildPhone){

        buildPhone.buildBattery();
        buildPhone.buildMicrophone();
        buildPhone.buildScreen();
        buildPhone.buildPhoneReceiver();
        buildPhone.buildPhoneBody();

        return buildPhone.build();
    }
}

• 屏蔽产品内部组成细节。
• 具体建造者类之间相互独立，容易扩展。
• 会产生多余的建造者对象和导演类。

另一种实现方式：

public class Student {

    String name = null;
    int number = -1;
    String sex = null;
    int age = -1;
    String school = null;

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", number=" + number +
                ", sex='" + sex + '\'' +
                ", age=" + age +
                ", school='" + school + '\'' +
                '}';
    }

    //构建器，利用构建器作为参数来构建Student对象
    public 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;
    }
}

  @Test
    public void thatTest(){
//        System.out.println(new Director().createMobilePhone(new IPhoneXBuilder()));
        Student a = new Student.StudentBuilder().setAge(13).setName("LiHua").build();
        Student b = new Student.StudentBuilder().setSchool("sc").setSex("Male").setName("ZhangSan").build();
        System.out.println(a);
        System.out.println(b);
    }