Java 使用jackson的MixIn类将JSON反序列化为JAX-B对象时出现异常
我们有一个简单的XSD文件。从该文件中,我们使用XJC生成Java对象。我们希望将这些对象序列化并反序列化为XML(有效)和JSON。有效的XML如下所示:Java 使用jackson的MixIn类将JSON反序列化为JAX-B对象时出现异常,java,json,xml,jackson,Java,Json,Xml,Jackson,我们有一个简单的XSD文件。从该文件中,我们使用XJC生成Java对象。我们希望将这些对象序列化并反序列化为XML(有效)和JSON。有效的XML如下所示: <user> <loginId>demo</loginId> <roles> <role>ADMIN</role> <role>USER</role> </roles> <
<user>
<loginId>demo</loginId>
<roles>
<role>ADMIN</role>
<role>USER</role>
</roles>
</user>
{
"loginId": "demo",
"roles": {
"role": ["ADMIN","USER"]
}
}
为了避免“角色”/“角色”构造,我们使用Mixin来获得以下结果:
{
"loginId": "demo",
"roles": ["ADMIN", "USER"]
}
这适用于序列化过程,但不适用于反序列化
下面是用于配置映射器和测试反序列化的代码:
public class JSONSupportTest {
private static final String USER_JSON = "{\n"
+ " \"loginId\": \"demo\",\n"
+ " \"roles\": [\n"
+ " \"ADMIN\",\n"
+ " \"USER\"\n"
+ " ]\n"
+ "}";
@Test
public void testJSONDeserialization() throws Exception {
ObjectMapper mapper = new ObjectMapper();
mapper.configure(SerializationFeature.WRAP_ROOT_VALUE, false);
mapper.setSerializationInclusion(Include.NON_NULL);
mapper.addMixIn(JAXBElement.class, JaxBElementMixin.class);
mapper.addMixIn(Roles.class, UserRolesMixin.class); // this line avoids the "roles"/"role" construct
UserType result = mapper.readValue(USER_JSON, UserType.class);
System.out.println(result);
}
}
使用该代码,我们将在以下异常中运行:
com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of de.demo.UserType$Roles out of START_ARRAY token
at [Source: (String)"{
"loginId": "demo",
"roles": [
"ADMIN",
"USER"
]
}"; line: 3, column: 14] (through reference chain: de.demo.UserType["roles"])
at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:63)
at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1329)
at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1138)
at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1092)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromArray(BeanDeserializerBase.java:1439)
at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeOther(BeanDeserializer.java:185)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:161)
at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:127)
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.ObjectMapper._readMapAndClose(ObjectMapper.java:4001)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2992)
at de.demo.JSONSupportTest.testJSONDeserialization(JSONSupportTest.java:22)
有没有一种方式Jackson支持两种方式(序列化和反序列化)
以下是完整的代码:
XSD文件:
<schema xmlns:tns="http://demo.de" elementFormDefault="qualified"
targetNamespace="http://demo.de" version="2.0"
xmlns="http://www.w3.org/2001/XMLSchema">
<element name="user" type="tns:UserType"/>
<complexType name="UserType">
<sequence>
<element minOccurs="1" maxOccurs="1" name="loginId" type="string" />
<element maxOccurs="1" minOccurs="1" name="roles">
<complexType>
<sequence>
<element maxOccurs="unbounded" minOccurs="1" name="role" type="tns:RoleType" />
</sequence>
</complexType>
</element>
</sequence>
</complexType>
<simpleType name="RoleType">
<restriction base="string">
<enumeration value="USER" />
<enumeration value="ADMIN" />
</restriction>
</simpleType>
XJC生成的JAX-B类:
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "UserType", propOrder = {
"loginId",
"roles"
})
public class UserType {
@XmlElement(required = true)
protected String loginId;
@XmlElement(required = true)
protected UserType.Roles roles;
public String getLoginId() {
return loginId;
}
public void setLoginId(String value) {
this.loginId = value;
}
public UserType.Roles getRoles() {
return roles;
}
public void setRoles(UserType.Roles value) {
this.roles = value;
}
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = {
"role"
})
public static class Roles {
@XmlElement(required = true)
@XmlSchemaType(name = "string")
protected List<RoleType> role;
public List<RoleType> getRole() {
if (role == null) {
role = new ArrayList<RoleType>();
}
return this.role;
}
}
}
@XmlType(name = "RoleType")
@XmlEnum
public enum RoleType {
USER,
ADMIN;
public String value() {
return name();
}
public static RoleType fromValue(String v) {
return valueOf(v);
}
}
@xmlacessortype(xmlacesstype.FIELD)
@XmlType(name=“UserType”,propOrder={
“loginId”,
“角色”
})
公共类用户类型{
@XmlElement(必需=true)
受保护字符串loginId;
@XmlElement(必需=true)
受保护的用户类型。角色;
公共字符串getLoginId(){
返回loginId;
}
public void setLoginId(字符串值){
this.loginId=值;
}
public UserType.Roles getRoles(){
返回角色;
}
public void setRoles(UserType.Roles值){
这个角色=价值;
}
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name=),比例={
“角色”
})
公共静态类角色{
@XmlElement(必需=true)
@XmlSchemaType(name=“string”)
受保护列表角色;
公共列表getRole(){
如果(角色==null){
role=newarraylist();
}
返回这个角色;
}
}
}
@XmlType(name=“RoleType”)
@XmlEnum
公共枚举角色类型{
用户,
管理
公共字符串值(){
返回名称();
}
公共静态角色类型fromValue(字符串v){
返回值(v);
}
}
最后是角色部分的Mixin类
public class UserRolesMixin extends Roles{
@JsonValue
@Override
public List<RoleType> getRole() {
return super.getRole();
}
}
public类UserRolesMixin扩展了角色{
@JsonValue
@凌驾
公共列表getRole(){
返回super.getRole();
}
}
我找到了一个带有自定义反序列化器的解决方案
public class UserRolesDeserializer extends JsonDeserializer<Roles> {
@Override
public Roles deserialize(JsonParser p, DeserializationContext ctxt) throws IOException, JsonProcessingException {
TreeNode node = p.readValueAsTree();
if (node instanceof ArrayNode) {
ArrayNode array = (ArrayNode) node;
Iterator<JsonNode> contentIter = array.iterator();
Roles result = new Roles();
while (contentIter.hasNext()) {
JsonNode valueNode = contentIter.next();
if (valueNode.isTextual()) {
String roleName = valueNode.textValue();
try {
RoleType role = RoleType.valueOf(roleName);
result.getRole().add(role);
} catch (IllegalArgumentException e) {
throw new JsonParseException(p,
"Can't create roles for user. Unknown role found. '" + roleName + "'", e);
}
} else {
throw new JsonParseException(p, "Can't create roles for user. All roles must be of type string");
}
}
return result;
} else {
throw new JsonParseException(p,
"Can't create roles for user. Unexpected content found. Array expected for element role");
}
}
公共类UserRolesDeserializer扩展JsonDeserializer{
@凌驾
公共角色反序列化(JsonParser p,DeserializationContext ctxt)引发IOException,JsonProcessingException{
TreeNode节点=p.readValueAsTree();
if(ArrayNode的节点实例){
ArrayNode数组=(ArrayNode)节点;
迭代器contentIter=array.Iterator();
角色结果=新角色();
while(contentIter.hasNext()){
JsonNode valueNode=contentIter.next();
if(valueNode.isTextual()){
字符串roleName=valueNode.textValue();
试一试{
RoleType角色=RoleType.valueOf(roleName);
result.getRole().add(角色);
}捕获(IllegalArgumentException e){
抛出新的JsonParseException(p,
无法为用户创建角色。找到未知角色。“+roleName+”,e);
}
}否则{
抛出新的JsonParseException(p,“无法为用户创建角色。所有角色必须是字符串类型”);
}
}
返回结果;
}否则{
抛出新的JsonParseException(p,
“无法为用户创建角色。找到意外内容。元素角色需要数组”);
}
}
以及更新的Mixin类
@JsonDeserialize(using = UserRolesDeserializer.class)
public class UserRolesMixin extends Roles {
@JsonValue
@Override
public List<RoleType> getRole() {
return super.getRole();
}
}
@JsonDeserialize(使用=UserRolesDeserializer.class)
公共类UserRoleMixin扩展了角色{
@JsonValue
@凌驾
公共列表getRole(){
返回super.getRole();
}
}
对我来说,这是jackson中的一个错误,它不是自动完成的,因为Mixin,应该清楚该做什么。但是出于某种原因,需要一个自定义反序列化程序。我找到了一个带有自定义反序列化程序的解决方案
public class UserRolesDeserializer extends JsonDeserializer<Roles> {
@Override
public Roles deserialize(JsonParser p, DeserializationContext ctxt) throws IOException, JsonProcessingException {
TreeNode node = p.readValueAsTree();
if (node instanceof ArrayNode) {
ArrayNode array = (ArrayNode) node;
Iterator<JsonNode> contentIter = array.iterator();
Roles result = new Roles();
while (contentIter.hasNext()) {
JsonNode valueNode = contentIter.next();
if (valueNode.isTextual()) {
String roleName = valueNode.textValue();
try {
RoleType role = RoleType.valueOf(roleName);
result.getRole().add(role);
} catch (IllegalArgumentException e) {
throw new JsonParseException(p,
"Can't create roles for user. Unknown role found. '" + roleName + "'", e);
}
} else {
throw new JsonParseException(p, "Can't create roles for user. All roles must be of type string");
}
}
return result;
} else {
throw new JsonParseException(p,
"Can't create roles for user. Unexpected content found. Array expected for element role");
}
}
公共类UserRolesDeserializer扩展JsonDeserializer{
@凌驾
公共角色反序列化(JsonParser p,DeserializationContext ctxt)引发IOException,JsonProcessingException{
TreeNode节点=p.readValueAsTree();
if(ArrayNode的节点实例){
ArrayNode数组=(ArrayNode)节点;
迭代器contentIter=array.Iterator();
角色结果=新角色();
while(contentIter.hasNext()){
JsonNode valueNode=contentIter.next();
if(valueNode.isTextual()){
字符串roleName=valueNode.textValue();
试一试{
RoleType角色=RoleType.valueOf(roleName);
result.getRole().add(角色);
}捕获(IllegalArgumentException e){
抛出新的JsonParseException(p,
无法为用户创建角色。找到未知角色。“+roleName+”,e);
}
}否则{
抛出新的JsonParseException(p,“无法为用户创建角色。所有角色必须是字符串类型”);
}
}
返回结果;
}否则{
抛出新的JsonParseException(p,
“无法为用户创建角色。找到意外内容。元素角色需要数组”);
}
}
以及更新的Mixin类
@JsonDeserialize(using = UserRolesDeserializer.class)
public class UserRolesMixin extends Roles {
@JsonValue
@Override
public List<RoleType> getRole() {
return super.getRole();
}
}
@JsonDeserialize(使用=UserRolesDeserializer.class)
公共类UserRoleMixin扩展了角色{
@JsonValue
@凌驾
公共列表getRole(){
返回super.getRole();
}
}
对我来说,这是jackson中的一个bug,它不是自动完成的,因为Mixin,应该很清楚该做什么。但是出于某种原因,需要一个自定义的反序列化程序