java - Jackson:根据字段存在选择子类进行反序列化

Question

我有以下模型:

public abstract class A {
    String commonField;
}

public class B extends A {    
}

public class C extends A {
    String customField;
}

如何根据存在的“customField”字段判断选择类(B 或 C)？

{ "commonField" : "..."} --> B instance

{ "commonField" : "...", "customField" : null} --> B instance

{ "commonField" : "...", "customField" : "..."} --> C instance

Answer 1

试试这个会有什么帮助

ObjectMapper mapper = new ObjectMapper();

String json = "{ \"commonField\" : \"...\", \"customField\"}";

JsonNode jsonNode = mapper.readTree( json );

A a; // class a

if(jsonNode.has( "customField" )) {

    a = mapper.convertValue( jsonNode, C.class );           
} else {

    a = mapper.convertValue( jsonNode, B.class );
}