4、建造者模式

一、创建型模式

    4、建造者模式

        (1)、概述

            将一个复杂的对象的构建与它的表示分离，是的同样的构建过程可以创建不同的表示。为了灵活构造复杂对象，该对象会有多个成员变量，在外部调用的时候，不需要或者不方便一次性创建出所有的成员变量，在这种情况下，使用多个构造方法去构建对象，很难维护，这时候Builder设计模式解决这个问题，进行buid()方法中创建对象，并且将builder传入，该builder中，维护了传入对象的成员变量。

            当一个类的构造函数参数个数超过4个，而且这些参数有些是可选的参数，考虑使用构造者模式。

        (2)、建造者模式应用

public class MaterialOrderBuilder {
    
    private ConsultDto consultDto;
 
    private CurrentUser currentUser;
 
    public MaterialOrderBuilder setConsultDto(ConsultDto consultDto){
        this.consultDto = consultDto;
        return this;
    }
 
    public MaterialOrderBuilder setCurrentUser(CurrentUser currentUser){
        this.currentUser = currentUser;
        return this;
    }
 
    /**
     * 构建方法
     * @return
     */
    public MaterialOrderDto build(){
        MaterialOrderDto materialOrderDto = new MaterialOrderDto();
        this.buildWithCurrentUser(materialOrderDto);
        this.buildWithConsultDto(materialOrderDto);
        this.buildOthers(materialOrderDto);
        return materialOrderDto;
    }
 
    private void buildWithCurrentUser(MaterialOrderDto materialOrderDtoReturn){
        if(NullUtil.isEmpty(currentUser)){
            return;
        }
        materialOrderDtoReturn.setTenantId(currentUser.getTenantId());
        ......
    }
 
    private void buildWithConsultDto(MaterialOrderDto materialOrderDtoReturn){
        if(NullUtil.isEmpty(consultDto)){
            return;
        }
        materialOrderDtoReturn.setVisitType(consultDto.getVisitType());
        ......
    }
 
    private void buildOthers(MaterialOrderDto materialOrderDtoReturn) {
        materialOrderDtoReturn.setId(UUIDUtil.getUUID());
        ......
    }
}
 
/**
 * 建造者模式应用
 * @return
 */
public static void main(String[] args) {
    //构建物资对接单对象
    MaterialOrderDto materialOrderDto = new MaterialOrderBuilder()
            .setConsultDto(consultDto)
            .setCurrentUser(currentUser)
            .build();
}

        (3)、借助lombok.Builder实现建造者模式

import lombok.Builder;
 
@Builder
public class DeliveryTaskBuilder {
 
    private Consult consult;
 
    private DoctorAdvice doctorAdvice;
 
    private AdviceFees adviceFees;
 
    private Integer status;
 
    /**
     * 医嘱build方法
     * @return
     */
    public DeliveryTask adviceBuild(){
        DeliveryTask deliveryTask = new DeliveryTask();
        this.buildWithConsult(deliveryTask);
        this.buildWithDoctorAdvice(deliveryTask);
        this.buildWithRecipe(deliveryTask);
        this.buildWithAdviceFees(deliveryTask);
        this.buildAdviceOthers(deliveryTask);
        return deliveryTask;
    }
 
    /**
     * 补费build方法
     * @return
     */
    public DeliveryTask feesBuild(){
        DeliveryTask deliveryTask = new DeliveryTask();
        this.buildWithConsult(deliveryTask);
        this.buildWithAdviceFees(deliveryTask);
        this.buildFeesOthers(deliveryTask);
        return deliveryTask;
    }
 
    private void buildWithConsult(DeliveryTask deliveryTask){
        if(NullUtil.isEmpty(consult)){
            return;
        }
        deliveryTask.setType(consult.getVisitType());
        deliveryTask.setPatientId(consult.getPatientId());
        ......
    }
 
    private void buildWithDoctorAdvice(DeliveryTask deliveryTask){
        if(NullUtil.isEmpty(doctorAdvice)){
            return;
        }
        deliveryTask.setCount(doctorAdvice.getCount());
        ......
    }
 
    private void buildWithAdviceFees(DeliveryTask deliveryTask){
        if(NullUtil.isEmpty(adviceFees)){
            return;
        }
        deliveryTask.setServiceId(adviceFees.getServiceId());
        deliveryTask.setUnitId(adviceFees.getCountUnitId());
        deliveryTask.setFootnote(adviceFees.getFootnote());
        ......
    }
 
    private void buildWithRecipe(DeliveryTask deliveryTask){
        if(NullUtil.isEmpty(recipe)){
            return;
        }
        deliveryTask.setOrderId(recipe.getRecipeId());
        deliveryTask.setOrderCode(recipe.getRecipeCode());
        ......
    }
 
    private void buildAdviceOthers(DeliveryTask deliveryTask) {
        deliveryTask.setStatus(status);
        ......
    }
 
    private void buildFeesOthers(DeliveryTask deliveryTask) {
        deliveryTask.setStatus(status);
        ......
    }
}
 
/**
 * lombok.Builder建造者模式应用
 * @return
 */
public static void main(String[] args) {
    //构建出库任务
    DeliveryTask deliveryTask = DeliveryTaskBuilder.builder()
          .consult(recipeAttribute.getConsult())
          .doctorAdvice(adviceGroupFees.getDoctorAdvice())
          .adviceFees(adviceFees)
          .recipe(adviceGroupFees.getRecipe())
          .status(DeliveryTaskConstant.deliveryTaskStatus.INIT_STATUA)
          .build()
          .adviceBuild();
}

            ①、People使用注解@Builder、@AllArgsConstructor(access = AccessLevel.PRIVATE)、@ToString

@Builder
@ToString
@AllArgsConstructor(access = AccessLevel.PRIVATE)
public class People {
    private String name;
    private String sex;
    private int age;
}

            ②、类People经过反编译后

                @AllArgsConstructor(access = AccessLevel.PRIVATE)注解将People构造方法标识为private

public class People {
 
    private String name;
    private String sex;
    private int age;
 
    private People(String name, String sex, int age) {
        this.name = name;
        this.sex = sex;
        this.age = age;
    }
 
    //生成的builder()方法
    public static People.PeopleBuilder builder() {
        return new People.PeopleBuilder();
    }
 
    //生成的内部类
    public static class PeopleBuilder {
        private String name;
        private String sex;
        private int age;
 
        PeopleBuilder() {
        }
 
        public People.PeopleBuilder name(String name) {
            this.name = name;
            return this;
        }
 
        public People.PeopleBuilder sex(String sex) {
            this.sex = sex;
            return this;
        }
 
        public People.PeopleBuilder age(int age) {
            this.age = age;
            return this;
        }
 
        //生成的build()方法
        public People build() {
            return new People(this.name, this.sex, this.age);
        }
 
        public String toString() {
            return "People.PeopleBuilder(name=" + this.name + ", sex=" + this.sex + ", age=" + this.age + ")";
        }
    }
 
    public String toString() {
        return "People(name=" + this.name + ", sex=" + this.sex + ", age=" + this.age + ")";
    }
}