如何从Lombok builder中排除属性？

Question

我有一个名为“XYZClientWrapper”的类，它具有以下结构：

@Builder
XYZClientWrapper{
    String name;
    String domain;
    XYZClient client;
}

我想要的是没有为属性XYZClient client生成的构建函数

Lombok是否支持此类用例？

Answer 1

是的，您可以将@Builder放在构造函数或静态（工厂）方法上，只包含您想要的字段。

披露：我是Lombok开发人员。

Answer 2

或者，我发现将一个字段标记为final，static或static final指示@Builder忽略该字段。

@Builder
public class MyClass {
   private String myField;

   private final String excludeThisField = "bar";
}

龙目岛1.16.10

Answer 3

我发现我能够实现静态Builder类的“shell”，使用私有访问修饰符添加我想要隐藏的方法，并且在构建器中不再可以访问它。同样，我也可以向构建器添加自定义方法。

package com.something;

import lombok.AccessLevel;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

import javax.persistence.AttributeOverride;
import javax.persistence.AttributeOverrides;
import javax.persistence.Column;
import javax.persistence.Embedded;
import javax.persistence.Entity;
import java.time.ZonedDateTime;

@Data
@Entity
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class MyClass{

    //The builder will generate a method for this property for us.
    private String anotherProperty;

    @Embedded
    @AttributeOverrides({
            @AttributeOverride(name = "localDateTime", column = @Column(name = "some_date_local_date_time")),
            @AttributeOverride(name = "zoneId", column = @Column(name = "some__date_zone_id"))
    })
    @Getter(AccessLevel.PRIVATE)
    @Setter(AccessLevel.PRIVATE)
    private ZonedDateTimeEmbeddable someDateInternal;

    public ZonedDateTime getSomeDate() {
        return someDateInternal.toZonedDateTime();
    }

    public void setSomeDate(ZonedDateTime someDate) {
        someDateInternal = new ZonedDateTimeEmbeddable(someDate);
    }

    public static class MyClassBuilder {
        //Prevent direct access to the internal private field by pre-creating builder method with private access.
        private MyClassBuilder shipmentDateInternal(ZonedDateTimeEmbeddable zonedDateTimeEmbeddable) {
            return this;
        }

        //Add a builder method because we don't have a field for this Type
        public MyClassBuilder someDate(ZonedDateTime someDate) {
            someDateInternal = new ZonedDateTimeEmbeddable(someDate);
            return this;
        }
    }

}

Answer 4

在代码中创建构建器并为您的属性添加私有setter。

@Builder
XYZClientWrapper{
    String name;
    String domain;
    XYZClient client;

    public static class XYZClientWrapperBuilder {
        private XYZClientWrapperBuilder client(XYZClient client) { return this; }
    }
}

Answer 5

这是我的首选解决方案。这样，您可以在最后创建字段client，并根据构建器先前设置的其他字段进行设置。

XYZClientWrapper{
    String name;
    String domain;
    XYZClient client;

    @Builder
    public XYZClientWrapper(String name, String domain) {
        this.name=name;this.domain=domain;
        this.client=calculateClient();
    }
}

Answer 6

对于工厂静态方法示例

Class Car{
   private String name;
   private String model;


   private Engine engine; // we want to ignore setting this

   @Builder
   public static Car of(String name, String model){
      Car car=new Car();
      car.setName(name);
      car.setModel(model);
      constructEngine(); // some private method to construct engine internally
      return car;  
   }

   private constructEngine(){// construct engine internally}
}

然后你可以使用如下：

main(String[] args){

   Car toyotaCorollaCar=Car.builder().name("Toyota").model("Corolla");
   // You can see now that Car.builder().engine() is not available

}

注意静态方法of将在调用build（）时被调用，所以像Car.builder().name("Toyota")这样的东西实际上不会将值"Toyota"设置为name，除非调用build()然后在构造函数中分配逻辑静态方法of被执行。

Answer 7

我找到了另一个解决方案您可以将您的字段包装到已启动的最终包装器或代理中。将其包装到AtomicReference中的最简单方法。

@Builder
public class Example {
    private String field1;
    private String field2;
    private final AtomicReference<String> excluded = new AtomicReference<>(null);
}

您可以通过get和set方法在其内部进行交互，但它不会出现在构建器中。

excluded.set("Some value");
excluded.get();