我实际上是在寻找一个“@Ignore”类型的注释,我可以用它来停止某个特定字段的持久化。如何实现这一目标?


当前回答

@瞬态符合您的需求。

其他回答

None of the above answers worked for me using Hibernate 5.2.10, Jersey 2.25.1 and Jackson 2.8.9. I finally found the answer (sort of, they reference hibernate4module but it works for 5 too) here. None of the Json annotations worked at all with @Transient. Apparently Jackson2 is 'smart' enough to kindly ignore stuff marked with @Transient unless you explicitly tell it not to. The key was to add the hibernate5 module (which I was using to deal with other Hibernate annotations) and disable the USE_TRANSIENT_ANNOTATION feature in my Jersey Application:

ObjectMapper jacksonObjectMapper = new ObjectMapper();
Hibernate5Module jacksonHibernateModule = new Hibernate5Module();
jacksonHibernateModule.disable(Hibernate5Module.Feature.USE_TRANSIENT_ANNOTATION);
jacksonObjectMapper.registerModule(jacksonHibernateModule);  

下面是Hibernate5Module的依赖:

<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-hibernate5</artifactId>
    <version>2.8.9</version>
</dependency>

@瞬态符合您的需求。

为了完成上面的回答,我使用了一个XML映射文件,其中@Transient和transient都不工作… 我必须把临时信息放在xml文件中:

<attributes>
(...)
    <transient name="field" />
</attributes>

显然,使用Hibernate5Module时,如果使用ObjectMapper, @Transient将不会被序列化。移除会让它起作用。

import javax.persistence.Transient;

import org.junit.Test;

import com.fasterxml.jackson.annotation.JsonInclude.Include;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

import lombok.Builder;
import lombok.Getter;
import lombok.Setter;
import lombok.extern.slf4j.Slf4j;

@Slf4j
public class TransientFieldTest {

    @Test
    public void Print_Json() throws JsonProcessingException {

        ObjectMapper objectEntityMapper = new ObjectMapper();
        //objectEntityMapper.registerModule(new Hibernate5Module());
        objectEntityMapper.setSerializationInclusion(Include.NON_NULL);

        log.info("object: {}", objectEntityMapper.writeValueAsString( //
                SampleTransient.builder()
                               .id("id")
                               .transientField("transientField")
                               .build()));

    }

    @Getter
    @Setter
    @Builder
    private static class SampleTransient {

        private String id;

        @Transient
        private String transientField;

        private String nullField;

    }
}

要忽略一个字段,请使用@Transient注释它,这样它就不会被hibernate映射。

但是jackson在转换为JSON时不会序列化字段。

如果你需要混合JPA和JSON(JPA省略,但仍然包含在Jackson中)使用@JsonInclude:

@JsonInclude()
@Transient
private String token;

TIP:

你也可以使用JsonInclude.Include。当token == null时,在反序列化期间在JSON中隐藏NON_NULL字段:

@JsonInclude(JsonInclude.Include.NON_NULL)
@Transient
private String token;