用Jackson进行反序列化

Question

我有一个用户界面：

public interface User{
    public static final String USER_KEY = "UK";
    public String getSessionKey();
    public List<Ties> getTies(); 
}

用户界面的一些层次结构：抽象类UserKind1实现User抽象类UserKind2实现User

public interface Ties{
    public String getId();
}

UserKind {1,2}的实现在UserKind {1,2} Factory中，例如：

public class UserKind1Factory {

    public static UserKind1 createUserKind1(List<Ties> tieses){
        return new UserKind1Impl(tieses);
    }
    public static UserKind1 createUserKind1(List<Ties> tieses, long sessionMaxTime){
        return new UserKind1Impl(tieses, sessionMaxTime);
    }

    private static class UserKind1Impl extends UserKind1{
        private List<Ties> legalTies;
        private long sessionMaxTime = 18000000;

        public UserKind1Impl(List<Ties> ties){
            this.ties = ties;
        }
        public UserKind1Impl(List<Ties> ties, long sessionMaxTime){
            this.ties = ties;
            this.sessionMaxTime = sessionMaxTime;
        } 
        ...
    }
}

和UserKind2和Ties的相同含义。

问题：如何正确使用Jackson进行反序列化UserKind1？

我对原始代码做了一些修改：

public class UserKind1Factory {

    @JsonCreator
    public static UserKind1 createUserKind1(@JsonProperty("ties") Ties[] ties, @JsonProperty("sessionMaxTime") long sessionMaxTime) {
        ArrayList tiesList = new ArrayList<Ties>();
        for (int i = 0; i < ties.length; i++) {
            tiesList.add(ties[i]);
        }
        return new UserKind1Impl(tiesList, sessionMaxTime);
    }

@JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include = JsonTypeInfo.As.PROPERTY, property = "@class")
public static class UserKind1Impl extends UserKind1{
...
}
}

@JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include = JsonTypeInfo.As.PROPERTY, property = "@class")
@JsonSubTypes({ @JsonSubTypes.Type(value = TiesFactory.TiesImpl.class, name = "ties")})
public interface Ties

public class TiesFactory {
@JsonCreator
    public static LegalTies createLegalTies(@JsonProperty("id") String id)

@JsonTypeInfo(use = JsonTypeInfo.Id.MINIMAL_CLASS, include = JsonTypeInfo.As.PROPERTY, property = "@class")
    public static class TiesImpl implements Ties{

... and get json:

{
  "@class" : "ua.company.model.user.impl.UserKind1Factory$UserKind1Impl",
  "legalTies" : [ {
    "@class" : "ua.company.model.user.impl.TiesFactory$TiesImpl",
    "id" : "100500"    
  }, {
    "@class" : "ua.company.model.user.impl.TiesFactory$TiesImpl",
    "id" : "200600"   
  } ],
  "sessionMaxTime" : 100501,
  "sessionKey" : "UK"
}

但是当我尝试反序列化时，它会崩溃，但异常：

org.codehaus.jackson.map.JsonMappingException: No suitable constructor
found for type [simple type, class
ua.company.model.user.impl.UserKind1Factory$UserKind1Impl]: can not
instantiate from JSON object (need to add/enable type information?) 
at [Source: [B@a85aa40; line: 2, column: 64]

Answer 1

org.codehaus.jackson.map.JsonMappingException: No suitable constructor found for type [simple type, class ua.company.model.user.impl.UserKind1Factory$UserKind1Impl]: can not instantiate from JSON object (need to add/enable type information?) at [Source: [B@a85aa40; line: 2, column: 64]

它本身具有的例外是您需要解决的所有事情就是为POJO类创建默认的构造函数