Java com.fasterxml.jackson.databind.JsonMappingException:无法反序列化START\u数组令牌的org.springframework.data.domain.Sort的实例

我的objectMapper正在获取类型

Page

的值，如下所示：

userList = objectMapper.readValue(RestAdapter.get(url), new TypeReference<PageImplBean<User>>(){});

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());
}
}

@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);
}    

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;
}

我的存储库类如下所示：

userList = objectMapper.readValue(RestAdapter.get(url), new TypeReference<PageImplBean<User>>(){});

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());
}
}

@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);
}    

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;
}

---

非常感谢您的帮助。谢谢。

我今天早上遇到了这个问题

定制定制器

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;
}

编辑：

下面是我收到的要反序列化的JSON（来自SpringDataCommons-1.9.2.RELEASE）：

如果您看一下，您将看到它实现了可迭代的for Order。如果您检查在同一个类中定义的顺序，您将在我的示例JSON中看到字段。因此，当排序被序列化时，它被序列化为顺序列表，这就是为什么反序列化为排序需要自定义反序列化器实现，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）

---

在反序列化过程中，当在反序列化每个属性时遇到带有@JsonDeserializer注释的setter时，Jackson使用提供的反序列化器反序列化该特定属性。

您有json示例吗？非常感谢。这正好解决了我的问题。但是，您能解释一下在实现这个CustomSortDeserializer类之前和之后，反序列化过程中到底发生了什么吗？我已经更新了我的回答，以帮助澄清您的问题。希望这有帮助！感谢您的更新和对幕后到底发生了什么的清晰描述。请注意，SpringDataCommons 2.0.x中的构造函数排序（orders）已被弃用。您可以用Sort.by（orders）替换行new Sort（orders）；