将JSON转换为Java Object,如何使用Jackson解析BadgerFish约定
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使用API我收到这样的JSON(现在保存到文件中):
[{
"LEI": {
"$": "549300Q82NZ9NYNMZT63"
},
"Entity": {
"LegalName": {
"$": "United Nerds in Collaboration of Random Nerdiness AB"
},
"LegalAddress": {
"Line1": {
"$": "BOX 155"
},
"City": {
"$": "Alingsas"
},
"Region": {
"$": "SE-O"
},
"Country": {
"$": "SE"
},
"PostalCode": {
"$": "44123"
}
},
"HeadquartersAddress": {
"Line1": {
"$": "BOX 155"
},
"City": {
"$": "Alingsas"
},
"Region": {
"$": "SE-O"
},
"Country": {
"$": "SE"
},
"PostalCode": {
"$": "44123"
}
},
"BusinessRegisterEntityID": {
"@register": "SE001",
"$": "5568557184"
},
"LegalJurisdiction": {
"$": "SE"
},
"LegalForm": {
"$": "PRIVATA AKTIEBOLAG"
},
"EntityStatus": {
"$": "ACTIVE"
}
},
"Registration": {
"InitialRegistrationDate": {
"$": "2016-06-23T01:48:45.025Z"
},
"LastUpdateDate": {
"$": "2016-06-23T01:48:44.945Z"
},
"RegistrationStatus": {
"$": "ISSUED"
},
"NextRenewalDate": {
"$": "2017-06-21T06:32:03.821Z"
},
"ManagingLOU": {
"$": "EVK05KS7XY1DEII3R011"
},
"ValidationSources": {
"$": "PARTIALLY_CORROBORATED"
}
}
}]
我想从这些中获取Java Object。我已经从提供的xsd文件中创建了Java对象。我正在运行的代码是:
public static void toJava() {
ObjectMapper mapper = new ObjectMapper();
try {
File json = new File("C:\temp\JSON.json");
LEIRecordType[] type = mapper.readValue(json, LEIRecordType[].class);
} catch (JsonEOFException ex) {
ex.printStackTrace();
} catch (JsonMappingException ex) {
ex.printStackTrace();
} catch (IOException ex) {
ex.printStackTrace();
}
}
这会创建以下异常:
com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "LEI" (class org.leiroc.data.schema.leidata._2014.LEIRecordType), not marked as ignorable (5 known properties: "lei", "registration", "entity", "nextVersion", "extension"])
at [Source: (File); line: 3, column: 14] (through reference chain: java.lang.Object[][0]->org.leiroc.data.schema.leidata._2014.LEIRecordType["LEI"])
at com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException.from(UnrecognizedPropertyException.java:60)
at com.fasterxml.jackson.databind.DeserializationContext.handleUnknownProperty(DeserializationContext.java:822)
at com.fasterxml.jackson.databind.deser.std.StdDeserializer.handleUnknownProperty(StdDeserializer.java:1152)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.handleUnknownProperty(BeanDeserializerBase.java:1567)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.handleUnknownVanilla(BeanDeserializerBase.java:1545)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:293)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:151)
at com.fasterxml.jackson.databind.deser.std.ObjectArrayDeserializer.deserialize(ObjectArrayDeserializer.java:195)
at com.fasterxml.jackson.databind.deser.std.ObjectArrayDeserializer.deserialize(ObjectArrayDeserializer.java:21)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4001)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2890)
at Test.JSONParser.toJava(JSONParser.java:38)
at Test.JSONParser.main(JSONParser.java:29)
LEIRecordType如下所示:
package org.leiroc.data.schema.leidata._2014;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlType;
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "LEIRecordType", propOrder = {"lei", "entity", "registration", "nextVersion", "extension"})
public class LEIRecordType {
@XmlElement(name = "LEI", required = true)
protected String lei;
@XmlElement(name = "Entity", required = true)
protected EntityType entity;
@XmlElement(name = "Registration", required = true)
protected RegistrationType registration;
@XmlElement(name = "NextVersion")
protected LEIRecordNextVersionType nextVersion;
@XmlElement(name = "Extension")
protected ExtensionType extension;
public String getLEI() {
return this.lei;
}
public void setLEI(String paramString) {
this.lei = paramString;
}
public EntityType getEntity() {
return this.entity;
}
public void setEntity(EntityType paramEntityType) {
this.entity = paramEntityType;
}
public RegistrationType getRegistration() {
return this.registration;
}
public void setRegistration(RegistrationType paramRegistrationType) {
this.registration = paramRegistrationType;
}
public LEIRecordNextVersionType getNextVersion() {
return this.nextVersion;
}
public void setNextVersion(LEIRecordNextVersionType paramLEIRecordNextVersionType) {
this.nextVersion = paramLEIRecordNextVersionType;
}
public ExtensionType getExtension() {
return this.extension;
}
public void setExtension(ExtensionType paramExtensionType) {
this.extension = paramExtensionType;
}
}
据我所知,问题是jackson正在锁定一个名为LEI的Java对象,其变量名为“$”。但没有。组织帮助服务说:
“$”对象总是重现相应XML元素的简单内容(即不是属性,子节点等)。“$”对象应始终在适用的地方键入JSON字符串。“
但据我所知,这不是JSON标准。
我的问题是:有没有办法让杰克逊解析这个LEI =“549300Q82NZ9NYNMZT63”等而不是和对象LEI的变量“$”?一天中的大部分时间都被困在这上面。
@UPDATE根据客户服务,这种JSON格式显然被称为“BadgerFish惯例”。
由于$
对象始终是String
,因此您可以为处理BadgerFish包装器对象的Strings创建自定义反序列化器。
此反序列化程序检查String
值周围是否存在BadgerFish包装器对象并将其解包。正常的String
值像往常一样被反序列化。
public class BadgerFishDeserializer extends StdDeserializer<String> {
private static final long serialVersionUID = 1L;
private static final SerializedString BADGER_FISH_FIELD_NAME = new SerializedString("$");
public BadgerFishDeserializer() {
super(String.class);
}
@Override
public String deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
// do we have a wrapper object?
if (jp.isExpectedStartObjectToken()) {
// check if first field name is equal to '$'
if (!jp.nextFieldName(BADGER_FISH_FIELD_NAME)) {
ctxt.reportInputMismatch(String.class, "Expected BadgerFish field name '$', but got '%s'", jp.getCurrentName());
}
jp.nextValue(); // proceed to the actual value
String value = jp.getValueAsString(); // read value as string
jp.nextToken(); // consume END_OBJECT of wrapper object
return value;
}
// else: just return string value
return jp.getValueAsString();
}
}
最后在Jackson ObjectMapper实例上注册模块:
SimpleModule module = new SimpleModule();
module.addDeserializer(String.class, new BadgerFishDeserializer());
mapper.registerModule(module);
注意:如果您只想要解包某些属性,可以创建自定义注释并使用BeanDeserializerModifier
检查注释,然后提供处理包装器对象的反序列化器。
一些值得思考的东西:
- 创建注释
- 修改反序列化器以始终指望包装器对象(在纯字符串上失败)
- 创建一个
DeserializerModifier
- 在
DeserializerModifier
上注册ObjectMapper
困难的部分:
public class BadgerFishDeserializerModifier extends BeanDeserializerModifier {
@Override
public BeanDeserializerBuilder updateBuilder(DeserializationConfig config, BeanDescription beanDesc, BeanDeserializerBuilder builder) {
Iterator<SettableBeanProperty> props = builder.getProperties();
while (props.hasNext()) {
SettableBeanProperty prop = props.next();
if (prop.getAnnotation(MyAnnotation.class) != null) {
builder.addOrReplaceProperty(prop.withValueDeserializer(new BadgerFishDeserializer()), true);
}
}
return builder;
}
}
这非常有帮助!我最终不得不为String和XMLGregorianCalendar做一个特殊的反序列化器。但问题并不止于此。 BadgerFish从生成的类中获取@XMLAttributes并将它们设置为@value而不是“value”。例如:
"BusinessRegisterEntityID": {
"@register": "SE001",
"$": "5568557184"
}
那么他们的任何方式也可以将字段名称自定义回原始名称?目前我现在得到这个例外:
Exception in thread "main" com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "@register" (class leigen.BusinessRegisterEntityIDType), not marked as ignorable (2 known properties: "value", "register"])
at [Source: (File); line: 44, column: 27] (through reference chain: java.lang.Object[][0]->leigen.LEIRecordType["Entity"]->leigen.EntityType["BusinessRegisterEntityID"]->leigen.BusinessRegisterEntityIDType["@register"])
at com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException.from(UnrecognizedPropertyException.java:60)
at com.fasterxml.jackson.databind.DeserializationContext.handleUnknownProperty(DeserializationContext.java:822)
at com.fasterxml.jackson.databind.deser.std.StdDeserializer.handleUnknownProperty(StdDeserializer.java:1152)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.handleUnknownProperty(BeanDeserializerBase.java:1567)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.handleUnknownVanilla(BeanDeserializerBase.java:1545)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:293)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:151)
at com.fasterxml.jackson.databind.deser.impl.FieldProperty.deserializeAndSet(FieldProperty.java:136)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:287)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:151)
at com.fasterxml.jackson.databind.deser.impl.FieldProperty.deserializeAndSet(FieldProperty.java:136)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:287)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:151)
at com.fasterxml.jackson.databind.deser.std.ObjectArrayDeserializer.deserialize(ObjectArrayDeserializer.java:195)
at com.fasterxml.jackson.databind.deser.std.ObjectArrayDeserializer.deserialize(ObjectArrayDeserializer.java:21)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4001)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2890)
at Test.JSONParser.toJava(JSONParser.java:47)
at Test.JSONParser.main(JSONParser.java:28)
我可以通过在配置中添加“ignore”(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)来绕过这个,就像我现在的代码一样:
public static LEIRecordType[] toJava(File json) throws JsonParseException, JsonMappingException, IOException {
ObjectMapper mapper = new ObjectMapper();
SimpleModule module = new SimpleModule();
module.addDeserializer(String.class, new BadgerFishStringDeserializer());
module.addDeserializer(XMLGregorianCalendar.class, new BadgerFishXMLGregorianCalendarDeserializer());
module.addDeserializer(NameType.class, new BadgerFishNameTypeDeserializer());
mapper.registerModule(module);
mapper.registerModule(new JaxbAnnotationModule()); // To be able to read JAXB annotations.
mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
return mapper.readValue(json, LEIRecordType[].class);
}
但是这只会将以@开头的值设置为null。还有另一种解决方法吗?否则,我将不得不为我生成的所有类编写一个自定义反序列化器,大约25个(在下一个版本中可能总会有更多)。我已经为NameType做了一个,但是对于其他示例,还需要更多。
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