即使使用 NON_NULL，Jackson ObjectMapper 也会抛出 NullPointerException [英] Jackson ObjectMapper throwing NullPointerException even with NON_NULL
问题描述
当使用以下 JSON 并且电话"或电子邮件地址"为空时，我收到 NullPointerException.
When the following JSON is used and either "phones" or "emailAddresses" are null, I'm getting a NullPointerException.
JSON:
{
"item": {
"messages": {
"user.phone.missing": {
"type": "warning",
"key": "user.phone.missing",
"message": "User profile does not have a phone number",
"code": null
},
"user.email.missing": {
"type": "warning",
"key": "user.email.missing",
"message": "User profile does not have an email address",
"code": null
},
"user.es.sync.failed": {
"type": "error",
"key": "user.es.sync.failed",
"message": "Unable to sync user",
"code": null
}
},
"user": {
"firstName": "Test",
"middleInitial": null,
"lastName": "User",
"createdDt": "2016-04-20 19:50:03+0000",
"updatedDt": null,
"lastVerifiedDt": null,
"status": "DEACTIVATED",
"tokens": [
{
"tokenHash": "test hash",
"tokenValue": "test dn",
"createdDt": "2016-04-20 19:50:03+0000",
"updatedDt": null,
"status": "ENABLED"
}
],
"phones": null,
"emailAddresses": null
}
},
"status": "SUCCESS",
"errors": []
}
这是堆栈跟踪:
Exception in thread "main" com.fasterxml.jackson.databind.JsonMappingException: N/A (through reference chain: com.test.message.cte.CteItemResponse["item"]->com.test.message.cte.CteUserContext["user"]->com.test.User["phones"])
at com.fasterxml.jackson.databind.deser.SettableBeanProperty._throwAsIOE(SettableBeanProperty.java:510)
at com.fasterxml.jackson.databind.deser.SettableBeanProperty._throwAsIOE(SettableBeanProperty.java:493)
at com.fasterxml.jackson.databind.deser.impl.MethodProperty.set(MethodProperty.java:116)
at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:98)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:295)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:121)
at com.fasterxml.jackson.databind.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:464)
at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:98)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:295)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:121)
at com.fasterxml.jackson.databind.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:464)
at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:98)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:295)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:121)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2888)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2041)
at com.test.Test.main(Test.java:20)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
Caused by: java.lang.NullPointerException
at com.test.User.setPhones(User.java:202)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.fasterxml.jackson.databind.deser.impl.MethodProperty.set(MethodProperty.java:114)
... 19 more
我正在像这样设置我的自定义 ObjectMapper:
I'm setting up my custom ObjectMapper like this:
package com.test;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.databind.util.ISO8601DateFormat;
public class MigrationObjectMapper extends ObjectMapper {
private MigrationObjectMapper() {
// do not serialize null value fields
this.setSerializationInclusion(JsonInclude.Include.NON_NULL);
configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
}
public static MigrationObjectMapper getMigrationObjectMapper(){
return new MigrationObjectMapper();
}
}
这意味着 CteUserContext cteUserContext = MigrationObjectMapper.getMigrationObjectMapper().convertValue(item.getItem(), new TypeReference 正在抛出错误.
Which means CteUserContext cteUserContext = MigrationObjectMapper.getMigrationObjectMapper().convertValue(item.getItem(), new TypeReference<CteUserContext>(){}); is throwing the error.
CteUserContext里面是一个User对象，里面包含List和List.这些不应该基于对象映射器配置进行序列化吗?
Inside CteUserContext is a User object, which contains List and List. Shouldn't these just not be serialized based on the object mapper configuration?
推荐答案
Per Rocki 的评论:
Per Rocki's comment:
setSerializationInclusion 将仅忽略空值序列化而不是反序列化.
setSerializationInclusion will ignore null values only for serialization not deserialization.
如果传入的电话"值在我的 User 类中为空，我没有处理，所以它抛出了 NPE.我已经更新以确认它不为空.如果是，它将在任何其他逻辑之前短路:
I wasn't handling if the incoming "phones" value was null in my User class, so it was throwing the NPE. I've updated to confirm that it isn't null. If it is, it'll short circuit before any other logic:
/**
* @param phones The phones
*/
@JsonProperty("phones")
public void setPhones(List<Phone> phones) {
if ((phones != null) && (phones.size() > 1)) {
int primaryIndex = -1;
Phone primaryPhone = null;
for (Phone p : phones) {
if (p.getIsPrimary()) {
primaryIndex = phones.indexOf(p);
primaryPhone = p;
break;
}
}
phones.remove(primaryIndex);
phones.add(0, primaryPhone);
}
this.phones = phones;
}
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