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
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>
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>
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;
有时候你想:
序列化一个列 忽略被持久化的列:
使用@Column(name = "columnName", insertable = false, updatable = false)
一个好的场景是通过使用其他列值自动计算某个列
@瞬态符合您的需求。
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;
}
}
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