我正在使用 Lombok 为我的 java 对象创建构建器模式，我想将 json 转换为该对象，但它一直说无法反序列化对象。
@Builder
@Getter
@Setter
@Value
@NoArgConstructor
@JsonDeserialize()
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
public class SaleInfo {
private String country;
private String saleability; //This
private boolean isEbook; //THis
// created only if required
private String buyLink;
//TODO i want to have a conditional creation of this two objects below.
ListPrice listPrice;
RetailPrice retailPrice;
@Override
public boolean equals(Object o) {
return EqualsBuilder.reflectionEquals(this, o);
}
@Override
public int hashCode() {
return HashCodeBuilder.reflectionHashCode(this);
}
@Override
public String toString() {
return ReflectionToStringBuilder.toString(this);
}
这是我使用对象映射器的代码
public NodeBean readFromJsonFile() throws IOException {
objectMapper.configure(
DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
InputStream resourceAsStream = getClass().getClassLoader().getResourceAsStream("book.json");
JsonNode node = objectMapper.readTree(resourceAsStream);
NodeBean nodebean = objectMapper.readerFor(NodeBean.class).readValue(node);
return nodebean;
}
当我实现 getter 和 setter 并删除所有 lombok 注释时，它工作得很好，但我需要它作为构建器模式，它很重要(由于一些可选对象，如 Listprice)。
当我尝试反序列化时出现错误
com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `com.valentine.cognifide_task.model.SaleInfo` (no Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator)
at [Source: UNKNOWN; line: -1, column: -1] (through reference chain: com.valentine.cognifide_task.model.NodeBean["items"]->java.util.ArrayList[0]->com.valentine.cognifide_task.model.Item["saleInfo"])
这是json，json的其他部分我有对象，它们都可以，只有saleInfo有问题，因为字段正在改变，有时它有Listprice，有时没有，所以我想要一个只会创建的构建器类如果需要的话。
{
"kind": "books#volume",
"id": "UEdjAgAAQBAJ",
"etag": "/KAuiIWJuB4",
"selfLink": "https://www.googleapis.com/books/v1/volumes/UEdjAgAAQBAJ",
"volumeInfo": {
"title": "Java. Podstawy. Wydanie IX",
"authors": [
"Cay S. Horstmann",
"Gary Cornell"
],
"publisher": "Helion",
"publishedDate": "2013-12-09",
"description": "Kolejne wydanie tej cenionej książki zostało zaktualizowane o wszystkie nowości, które pojawiły się w wersji 7 platformy Java Standard Edition. W trakcie lektury poznasz składnię języka oraz wszystkie istotne kwestie związane z programowaniem w Javie. Zrozumiesz założenia programowania obiektowego, nauczysz się korzystać z interfejsów oraz obsługiwać wyjątki. Przekonasz się również, jakie ułatwienia w tym zakresie oferuje Java 7 obsługa wielu wyjątków w ramach jednego bloku catch to tylko czubek góry lodowej.",
"industryIdentifiers": [
{
"type": "ISBN_13",
"identifier": "9788324677610"
},
{
"type": "ISBN_10",
"identifier": "8324677615"
}
],
"readingModes": {
"text": true,
"image": true
},
"pageCount": 864,
"printType": "BOOK",
"categories": [
"Computers"
],
"maturityRating": "NOT_MATURE",
"allowAnonLogging": true,
"contentVersion": "2.5.4.0.preview.3",
"imageLinks": {
"smallThumbnail": "http://books.google.com/books/content?id=UEdjAgAAQBAJ&printsec=frontcover&img=1&zoom=5&edge=curl&source=gbs_api",
"thumbnail": "http://books.google.com/books/content?id=UEdjAgAAQBAJ&printsec=frontcover&img=1&zoom=1&edge=curl&source=gbs_api"
},
"language": "pl",
"previewLink": "http://books.google.pl/books?id=UEdjAgAAQBAJ&pg=PA852&dq=java&hl=&cd=4&source=gbs_api",
"infoLink": "https://play.google.com/store/books/details?id=UEdjAgAAQBAJ&source=gbs_api",
"canonicalVolumeLink": "https://market.android.com/details?id=book-UEdjAgAAQBAJ"
},
"saleInfo": {
"country": "PL",
"saleability": "FOR_SALE",
"isEbook": true,
"listPrice": {
"amount": 79.0,
"currencyCode": "PLN"
},
"retailPrice": {
"amount": 55.3,
"currencyCode": "PLN"
},
"buyLink": "https://play.google.com/store/books/details?id=UEdjAgAAQBAJ&rdid=book-UEdjAgAAQBAJ&rdot=1&source=gbs_api",
"offers": [
{
"finskyOfferType": 1,
"listPrice": {
"amountInMicros": 7.9E7,
"currencyCode": "PLN"
},
"retailPrice": {
"amountInMicros": 5.53E7,
"currencyCode": "PLN"
}
}
]
},
"accessInfo": {
"country": "PL",
"viewability": "PARTIAL",
"embeddable": true,
"publicDomain": false,
"textToSpeechPermission": "ALLOWED",
"epub": {
"isAvailable": true,
"acsTokenLink": "http://books.google.pl/books/download/Java_Podstawy_Wydanie_IX-sample-epub.acsm?id=UEdjAgAAQBAJ&format=epub&output=acs4_fulfillment_token&dl_type=sample&source=gbs_api"
},
"pdf": {
"isAvailable": true,
"acsTokenLink": "http://books.google.pl/books/download/Java_Podstawy_Wydanie_IX-sample-pdf.acsm?id=UEdjAgAAQBAJ&format=pdf&output=acs4_fulfillment_token&dl_type=sample&source=gbs_api"
},
"webReaderLink": "http://play.google.com/books/reader?id=UEdjAgAAQBAJ&hl=&printsec=frontcover&source=gbs_api",
"accessViewStatus": "SAMPLE",
"quoteSharingAllowed": false
},
"searchInfo": {
"textSnippet": "MF, 512 manifestu klasa główna, 514 sekcja główna, 512 wstawianie sekcji, 518 \u003cbr\u003e\nzmienianie zawartości, 513 MapTest.\u003cb\u003ejava\u003c/b\u003e,699 MenuFrame.\u003cb\u003ejava\u003c/b\u003e, 442 \u003cbr\u003e\nMethodTableTest.\u003cb\u003ejava\u003c/b\u003e,266 MouseComponent.\u003cb\u003ejava\u003c/b\u003e, 383 MouseFrame.\u003cb\u003ejava\u003c/b\u003e, 383 \u003cbr\u003e\nNotHelloWorld.\u003cb\u003ejava\u003c/b\u003e, 330, 534 ObjectAnalyzerTest.\u003cb\u003ejava\u003c/b\u003e,259 OptionDialogFrame.\u003cbr\u003e\n\u003cb\u003ejava\u003c/b\u003e,477 overview.html, 194 PackageTest.\u003cb\u003ejava\u003c/b\u003e, 184 PairTest1.\u003cb\u003ejava\u003c/b\u003e, 631 \u003cbr\u003e\nPairTest2.\u003cb\u003ejava\u003c/b\u003e, 634 PairTest3.\u003cb\u003ejava\u003c/b\u003e, 656 ParamTest.\u003cb\u003ejava\u003c/b\u003e, 169 PasswordChooser.\u003cbr\u003e\n\u003cb\u003ejava\u003c/b\u003e, 492 Person.\u003cb\u003ejava\u003c/b\u003e ..."
}
},
最佳答案
您似乎缺少带有 @JsonCreator 标记和参数上的 @JsonProperty 标记的构造函数。
我现在正在开发一个项目，我在 jax-rs 上下文中使用它。
Looking into it ，看来 Jackson 可能实际上并没有使用所需的属性。
@Builder
@Getter
@Setter
@Value
@RequiredArgsConstructor
@JsonDeserialize()
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
public class SaleInfo {
private String country;
private String saleability; //This
private boolean isEbook; //THis
// created only if required
private String buyLink;
//TODO i want to have a conditional creation of this two objects below.
ListPrice listPrice;
RetailPrice retailPrice;
@JsonCreator
public SaleInfo(
@JsonProperty("country") String country;
@JsonProperty("saleability") String saleability;
@JsonProperty("isEbook") boolean isEbook;
@JsonProperty(value = "buyLink", required = false) String buyLink;
@JsonProperty(value = "listPrice", required = false) ListPrice listPrice;
@JsonProperty(value = "retailPrice", required = false) RetailPrice retailPrice;
) {
this.country = country;
this.saleability = saleability;
this.isEbook = isEbook;
this.buyLink = buyLink;
this.listPrice = listPrice;
this.retailPrice = country;
}
@Override
public boolean equals(Object o) {
return EqualsBuilder.reflectionEquals(this, o);
}
@Override
public int hashCode() {
return HashCodeBuilder.reflectionHashCode(this);
}
@Override
public String toString() {
return ReflectionToStringBuilder.toString(this);
}
关于java - 将Json反序列化为java对象，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/55551713/