我的objectMapper正在获取类型Page<User>
的值,如下所示:
userList = objectMapper.readValue(RestAdapter.get(url), new TypeReference<PageImplBean<User>>(){});
PageImplBean
扩展PageImpl
课程如下:
public class PageImplBean<T> extends PageImpl<T> {
private static final long serialVersionUID = 1L;
private int number;
private int size;
private int totalPages;
private int numberOfElements;
private long totalElements;
private boolean previousPage;
private boolean first;
private boolean nextPage;
private boolean last;
private List<T> content;
private Sort sort;
public PageImplBean() {
super(new ArrayList<T>());
}
public int getNumber() {
return number;
}
public void setNumber(int number) {
this.number = number;
}
public int getSize() {
return size;
}
public void setSize(int size) {
this.size = size;
}
public int getTotalPages() {
return totalPages;
}
public void setTotalPages(int totalPages) {
this.totalPages = totalPages;
}
public int getNumberOfElements() {
return numberOfElements;
}
public void setNumberOfElements(int numberOfElements) {
this.numberOfElements = numberOfElements;
}
public long getTotalElements() {
return totalElements;
}
public void setTotalElements(long totalElements) {
this.totalElements = totalElements;
}
public boolean isPreviousPage() {
return previousPage;
}
public void setPreviousPage(boolean previousPage) {
this.previousPage = previousPage;
}
public boolean isNextPage() {
return nextPage;
}
public void setNextPage(boolean nextPage) {
this.nextPage = nextPage;
}
public boolean isFirst() {
return first;
}
public void setFirst(boolean first) {
this.first = first;
}
public boolean isLast() {
return last;
}
public void setLast(boolean last) {
this.last = last;
}
public List<T> getContent() {
return content;
}
public void setContent(List<T> content) {
this.content = content;
}
public Sort getSort() {
return sort;
}
public void setSort(Sort sort) {
this.sort = sort;
}
public PageImpl<T> pageImpl() {
return new PageImpl<T>(getContent(), new PageRequest(getNumber(),
getSize(), getSort()), getTotalElements());
}
}
我的存储库类如下所示:
@EnableScan
@EnableScanCount
public abstract interface UserRepository extends PagingAndSortingRepository<User, String>
{
public abstract Page<User> findByAddressId(String paramString, Pageable paramPageable);
public abstract Page<User> findAll(Pageable paramPageable);
}
我的服务类如下:
public Page<User> fetchUserList(String addressId,Integer pageNumber, Integer pageSize){
Page<User> userPageList = null;
PageRequest pageRequest = new PageRequest(pageNumber - 1, pageSize, Direction.ASC, "addressId");
userPageList = userRepository.findByAddressId(addressId, pageRequest);
return userPageList;
}
来自webservice的我的Page<User>
对象由一个带有对象Sort的可分页实例组成,该实例包含值[addressId:ASC]。
使用objectMapper将对象反序列化为userList,如上所示,我遇到了上述错误。
com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of org.springframework.data.domain.Sort out of START_ARRAY token
任何帮助非常感谢。谢谢。
答案 0 :(得分:13)
今天早上我遇到了这个问题。
CustomSortDeserializer
import java.io.IOException;
import org.springframework.data.domain.Sort;
import org.springframework.data.domain.Sort.Direction;
import org.springframework.data.domain.Sort.Order;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.ArrayNode;
public class CustomSortDeserializer extends JsonDeserializer<Sort> {
@Override
public Sort deserialize(JsonParser jp, DeserializationContext ctxt)
throws IOException, JsonProcessingException {
ArrayNode node = jp.getCodec().readTree(jp);
Order[] orders = new Order[node.size()];
int i = 0;
for(JsonNode obj : node){
orders[i] = new Order(Direction.valueOf(obj.get("direction").asText()), obj.get("property").asText());
i++;
}
Sort sort = new Sort(orders);
return sort;
}
然后在PageImplBean的public void setSort(Sort sort)方法中添加以下内容:
@JsonDeserialize(using=CustomSortDeserializer.class)
public void setSort(Sort sort) {
this.sort = sort;
}
编辑:
这是我收到的用于反序列化的JSON(来自spring-data-commons - 1.9.2.RELEASE):
[
{
"direction": "ASC",
"property": "amount",
"ignoreCase": false,
"nullHandling": "NATIVE",
"ascending": true
},
{
"direction": "ASC",
"property": "effectiveDate",
"ignoreCase": false,
"nullHandling": "NATIVE",
"ascending": true
}
]
如果查看Sort,您会看到它为Order实现了Iteratable。如果您检查在同一个类中定义的Order,您将看到我的示例JSON中的字段。因此,当Sort被序列化时,它被序列化为Order列表,这就是为什么反序列化为Sort需要自定义反序列化器实现的原因,以及为什么没有自定义实现的反序列化失败(因为它试图将数组反序列化为单个对象)。
在反序列化期间,当每个属性被反序列化时遇到使用@JsonDeserializer注释的setter时,Jackson使用提供的反序列化器来反序列化该特定属性。