Gson désérialiser json. java.lang.RuntimeException: impossible d'appeler public com.derp.procédure.de modèle.SkeletonElement() sans arguments] à cause de racine

C'est ma première fois avec json et java. J'ai vérifier beaucoup de question/post avec le même message d'erreur semblable à la mienne. Mais je n'ai pas trouver quelque chose d'utile.

J'ai uderstood que j'ai du ajouter pas args constructeur. J'ai maded, mais ça ne m'a aidé. Toujours la même erreur se produire. Il peut travailler de cette façon. Je pense que c'est lié avec assez complecated iheritance de la mine de code.

ERREUR:

SEVERE: Servlet.service() for servlet [dispatcher] in context with path [/derp] threw exception [Request processing failed; nested exception is java.lang.RuntimeException: Failed to invoke public com.derp.procedure.model.SkeletonElement() with no args] with root cause java.lang.InstantiationException

StackTrace:

gru 19, 2014 8:27:50 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [dispatcher] in context with path [/derp] threw exception [Request processing failed; nested exception is java.lang.RuntimeException: Failed to invoke public com.derp.procedure.model.SkeletonElement() with no args] with root cause
java.lang.InstantiationException
at sun.reflect.InstantiationExceptionConstructorAccessorImpl.newInstance(InstantiationExceptionConstructorAccessorImpl.java:48)
at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
at com.google.gson.internal.ConstructorConstructor$3.construct(ConstructorConstructor.java:104)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:186)
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:40)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:81)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:60)
at com.google.gson.Gson.fromJson(Gson.java:810)
at com.google.gson.Gson.fromJson(Gson.java:775)
at com.google.gson.Gson.fromJson(Gson.java:724)
at com.derp.procedure.model.SkeletonElement.toObject(SkeletonElement.java:38)
at com.derp.procedure.model.Skeleton.setSkeletonElements(Skeleton.java:53)
at com.derp.procedure.controller.ProcedureController.elementsAssignmentSubmit(ProcedureController.java:81)
at com.derp.procedure.controller.ProcedureController$$FastClassBySpringCGLIB$$35de90ba.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:717)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:98)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:266)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:95)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:653)
at com.derp.procedure.controller.ProcedureController$$EnhancerBySpringCGLIB$$fe2945ed.elementsAssignmentSubmit(<generated>)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:781)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:721)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)
at org.springframework.web.servlet.FrameworkServlet.doPut(FrameworkServlet.java:879)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:136)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:526)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1078)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:655)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:146)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:279)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)

Mes classes java:

Modèle générique de la classe qui est étendu:

package com.derp.generic.model;
import java.io.IOException;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.MappedSuperclass;
import javax.persistence.Transient;
import org.apache.commons.lang.builder.ToStringBuilder;
import org.apache.commons.lang.builder.ToStringStyle;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.annotate.JsonMethod;
import org.codehaus.jackson.annotate.JsonAutoDetect.Visibility;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
@MappedSuperclass
public abstract class GenericModel<T extends GenericModel<?>> {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
public long getId() {return id;}
public void setId(long id) {this.id = id;}
public GenericModel() {
}
//a toString method that can be used in any class.
//uses reflection to dynamically print java class field
//values one line at a time.
@Override
public String toString() {
return ToStringBuilder.reflectionToString(this, ToStringStyle.MULTI_LINE_STYLE);
}
public String toJson() {
ObjectMapper jsonMapper = new ObjectMapper();
try {
return jsonMapper.writerWithDefaultPrettyPrinter().writeValueAsString(this);
} catch (JsonGenerationException e) {
e.printStackTrace();
return null;
} catch (JsonMappingException e) {
e.printStackTrace();
return null;
} catch (IOException e) {
e.printStackTrace();
return null;
}
}
//public GenericModel<T> toObject(String jsonObject) {
//Suggested by stackOverflowComunity at:
//https://stackoverflow.com/questions/27532206/java-create-list-of-objects-from-json-string-with-jackson
public <T> T toObject(String jsonObject) {
ObjectMapper jsonMapper = new ObjectMapper();
try {
//GenericModel<T> t = jsonMapper.readValue(jsonObject, GenericModel.class);
T t = (T) jsonMapper.readValue(jsonObject, GenericModel.class);
//return t;
return t;
} catch (JsonGenerationException e) {
e.printStackTrace();
return null;
} catch (JsonMappingException e) {
e.printStackTrace();
return null;
} catch (IOException e) {
e.printStackTrace();
return null;
}
}
}   

Hiérarchique générique classe qui étend la classe générique modèle:

package com.derp.generic.model;
import java.io.IOException;
import java.util.LinkedList;
import java.util.List;
import javax.persistence.CascadeType;
import javax.persistence.FetchType;
import javax.persistence.ManyToOne;
import javax.persistence.MappedSuperclass;
import javax.persistence.OneToMany;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
@MappedSuperclass
public abstract class GenericHierarchicalModel<T extends GenericHierarchicalModel<T>> extends GenericModel<T> {
private String name;
@ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
private T parent;
@OneToMany(mappedBy = "parent")
private List<T> children;
public String getName() {return name;}
public void setName(String name) {this.name = name;}
public T getParent() {return parent;}
public void setParent(T parent) {this.parent = parent;}
public List<T> getChildren() {return children;}
public void setChildren(List<T> children) {this.children = children;}
public GenericHierarchicalModel() {
super();
}
@Override
public String toJson() {
return "{\"title\":\"" + this.name + "\", \"id\":\"" + this.getId() + "\", \"children\": [" + listToJson(this.getChildren()) + "]}";
}
public String listToJson(List<T> children) {
String json = "";
for(int i=0; i<children.size(); i++) {
json = json + children.get(i).toJson();
if(children.size()!=i+1) {
json = json + ", ";
}
}
return json;
}
// @Override
// public GenericHierarchicalModel<T> toObject(String jsonObject) {
//     int start = 0; //'(' position in string
//     int end = 0; //')' position in string
//     for(int i = 0; i < jsonObject.length(); i++) { 
//         if(jsonObject.charAt(i) == '{') //Looking for '{' position in string
//            start = i;
//         else if(jsonObject.charAt(i) == '}') //Looking for '}' position in  string
//            end = i;
//     }
//     String number = jsonObject.substring(start+1, end); //you take value between start and end
//     System.out.println(number);
//     return null;
// }
}

De la classe du modèle que je suis en train de désérialiser de json liste des objets:

package com.derp.procedure.model;
import java.io.IOException;
import java.util.List;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.Entity;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.Table;
import javax.persistence.Transient;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
import com.derp.generic.model.GenericHierarchicalModel;
import com.derp.generic.model.GenericModel;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
@Entity
@Table(name="procedure__SkeletonElement")
@Inheritance(strategy=InheritanceType.JOINED)
@DiscriminatorColumn(name="type")
public abstract class SkeletonElement extends GenericHierarchicalModel<SkeletonElement> {
@Transient
public String getDecriminatorValue() {
return this.getClass().getSimpleName();
}
@Override
public String toJson() {
return "{\"title\":\"" + this.getName() + "\", \"id\":\"" + this.getId() + "\", \"type\":\"" + this.getDecriminatorValue() + "\", \"children\": [" + listToJson(this.getChildren()) + "]}";
}
public List<SkeletonElement> toObject(String jsonObject) {
Gson gson = new Gson(); //Or use new GsonBuilder().create();
//SkeletonElement[] target2 = gson.fromJson(jsonObject, SkeletonElement[].class);
List<SkeletonElement> target2 = gson.fromJson(jsonObject, new TypeToken<List<SkeletonElement>>(){}.getType());
return target2;
}
public SkeletonElement() {
super();
}
}

Et la classe qui contient la collection de l'objet que je suis en train de désérialiser retour à java liste des objets:

package com.derp.procedure.model;
import java.util.LinkedList;
import java.util.List;
import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.ManyToMany;
import javax.persistence.Table;
import com.derp.generic.model.GenericDictionaryModel;
@Entity
@Table(name="procedure__Skeleton")
public class Skeleton extends GenericDictionaryModel<Skeleton> {
@ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
private List<SkeletonElement> skeletonElements;
public void setSkeletonElements(List<SkeletonElement> skeletonElements) {this.skeletonElements = skeletonElements;}
public List<SkeletonElement> getSkeletonElements() {return skeletonElements;}
public List<SkeletonElement> getSkeletonParentsElements() {
List<SkeletonElement> skeletonParentsElements = new LinkedList<SkeletonElement>();
for(int i=0; i<this.skeletonElements.size(); i++) {
if(this.skeletonElements.get(i).getParent()==null) {
skeletonParentsElements.add(this.getSkeletonElements().get(i));
}
}
return skeletonParentsElements;
}
public Skeleton(String name) {
super(name);
}
public Skeleton() {
//TODO Auto-generated constructor stub
}
public String getSkeletonElementsJsonTree() {
String jsonTreeString ="[";
List<SkeletonElement> skeletonParentsElements = getSkeletonParentsElements();
for(int i=0; i<skeletonParentsElements.size(); i++) {
jsonTreeString = jsonTreeString + skeletonParentsElements.get(i).toJson();
if((1+i) != skeletonParentsElements.size()) {
jsonTreeString = jsonTreeString + ",";
}
}
return jsonTreeString + "]";
}
public void setSkeletonElements(String skeletonElementsJson) {
this.skeletonElements.get(0).toObject(skeletonElementsJson);
}
}

Et au moins ma chaîne json que j'ai l'habitude de désérialiser:

[
{
"name": "Title1",
"id": "1",
"type": "SkeletonJobElement",
"parent_id": "null",
"children": [
{
"name": "Title11",
"id": "2",
"type": "SkeletonJobElement",
"parent_id": "1",
"children": [
{
"name": "Title111",
"id": "5",
"type": "SkeletonFileElement",
"parent_id": "2",
"children": []
},
{
"name": "Title112",
"id": "6",
"type": "SkeletonFileElement",
"parent_id": "2",
"children": []
}
]
}
]
},
{
"name": "Title2",
"id": "3",
"type": "SkeletonJobElement",
"parent_id": "null",
"children": [
{
"name": "Title21",
"id": "4",
"type": "SkeletonJobElement",
"parent_id": "3",
"children": []
}
]
}
]

Je sais que c'est beaucoup de code à l'analyse, mais s'il vous plaît m'aider à le comprendre.
J'ai du mal avec elle, pour la semaine si longtemps.