使用没有注释的@JsonIdentityInfo [英] Using @JsonIdentityInfo without annotations
问题描述
我使用Jackson 2.2.3将POJO序列化为JSON。然后我遇到了问题,我无法序列化递归结构......我通过使用解决了这个问题@JsonIdentityInfo
=>效果很好。
I use Jackson 2.2.3 to serialize POJOs to JSON. Then I had the problem, that I couldn't serialize recursive structures...I solved this problem by using @JsonIdentityInfo
=> works great.
但是,我不希望这个注释位于我的POJO之上。
But, I don't want this annotation on the top of my POJO.
所以我的问题是:是否还有其他可能设置我的 ObjectMapper
的默认行为来使用该功能每个POJO?
So my question is: Is there any other possibility to set the default behavior of my ObjectMapper
to use the feature for every POJO?
所以我想转换这个注释代码
So I want to transform this annotation code
@JsonIdentityInfo(generator=ObjectIdGenerators.IntSequenceGenerator.class, property="@id")
类似于
ObjectMapper om = new ObjectMapper();
om.setDefaultIdentityInfo(ObjectIdGenerators.IntSequenceGenerator.class, "@id");
任何想法?
推荐答案
您可以使用 Jackson混合注释或 Jackson注释内省运动员。
这是一个显示两种方法的示例:
Here is an example showing both methods:
public class JacksonJsonIdentityInfo {
@JsonIdentityInfo(
generator = ObjectIdGenerators.IntSequenceGenerator.class, property = "@id")
static class Bean {
public final String field;
public Bean(final String field) {this.field = field;}
}
static class Bean2 {
public final String field2;
public Bean2(final String field2) {this.field2 = field2;}
}
@JsonIdentityInfo(
generator = ObjectIdGenerators.IntSequenceGenerator.class, property = "@id2")
static interface Bean2MixIn {
}
static class Bean3 {
public final String field3;
public Bean3(final String field3) {this.field3 = field3;}
}
static class MyJacksonAnnotationIntrospector extends JacksonAnnotationIntrospector {
@Override
public ObjectIdInfo findObjectIdInfo(final Annotated ann) {
if (ann.getRawType() == Bean3.class) {
return new ObjectIdInfo(
PropertyName.construct("@id3", null),
null,
ObjectIdGenerators.IntSequenceGenerator.class,
null);
}
return super.findObjectIdInfo(ann);
}
}
public static void main(String[] args) throws JsonProcessingException {
final Bean bean = new Bean("value");
final Bean2 bean2 = new Bean2("value2");
final Bean3 bean3 = new Bean3("value3");
final ObjectMapper mapper = new ObjectMapper();
mapper.addMixInAnnotations(Bean2.class, Bean2MixIn.class);
mapper.setAnnotationIntrospector(new MyJacksonAnnotationIntrospector());
System.out.println(mapper.writeValueAsString(bean));
System.out.println(mapper.writeValueAsString(bean2));
System.out.println(mapper.writeValueAsString(bean3));
}
}
输出:
{"@id":1,"field":"value"}
{"@id2":1,"field2":"value2"}
{"@id3":1,"field3":"value3"}
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