我正在将地图转换为对象,但是地图的某些值为Json String,我尝试使用杰克逊将其转换为下面的代码,但失败了。
public class Father {
private String name;
private List<Child> children;
}
public class Child {
private String name;
}
public static void main(String[] args) throws InvocationTargetException, IllegalAccessException {
String s= JSON.toJSONString(Arrays.asList(new Child("Bob"),new Child("Jackson")));
Map<String,String> map=new HashMap();
map.put("name","Jack")
map.put("children",s);
// how to convert the map to a Father Object?
//this does not work
ObjectMapper mapper = new ObjectMapper();
mapper.convertValue(map, Father.class);
}
编辑:这是个例外:
Exception in thread "main" java.lang.IllegalArgumentException: Cannot deserialize instance of `java.util.ArrayList` out of VALUE_STRING token
at [Source: UNKNOWN; line: -1, column: -1] (through reference chain: model.Father["children"])
at com.fasterxml.jackson.databind.ObjectMapper._convert(ObjectMapper.java:3750)
at com.fasterxml.jackson.databind.ObjectMapper.convertValue(ObjectMapper.java:3668)
at service.BasicBehavior.main(BasicBehavior.java:25)
Caused by: com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `java.util.ArrayList` out of VALUE_STRING token
at [Source: UNKNOWN; line: -1, column: -1] (through reference chain: model.Father["children"])
at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:63)
at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1343)
at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1139)
at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1093)
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.handleNonArray(CollectionDeserializer.java:332)
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:265)
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:245)
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:27)
at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:127)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:288)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:151)
at com.fasterxml.jackson.databind.ObjectMapper._convert(ObjectMapper.java:3745)
... 2 more
答案 0 :(得分:0)
如果您使用customdeserializer序列化您的类,那就可以了。问题是您无法转换Child
类。
public class CustomStringDeserializer extends JsonDeserializer<List<Child>> {
@Override
public List<Child> deserialize(JsonParser parser, DeserializationContext ctxt)
throws IOException, JsonProcessingException {
List<Child> ret = new ArrayList<>();
ObjectCodec codec = parser.getCodec();
ObjectMapper mapper = new ObjectMapper();
TreeNode node = codec.readTree(parser);
if (node.isArray()){
for (JsonNode n : (ArrayNode)node){
ret.add(mapper.convertValue(n, Child.class));
}
} else if (node.isValueNode()){
ret.add(mapper.convertValue(node, Child.class));
}
return ret;
}
}
当然,您应该在Father
类中将此反序列化器用作批注。
@JsonDeserialize(using = CustomStringDeserializer.class)
private List<Child> children;
此外,您应该这样使用Map<String, Object>
Map<String,Object> map = new HashMap();
map.put("name","Jack");
map.put("children", Arrays.asList(new Child("Bob"),new Child("Jackson")));
所有这些更改之后,它将起作用。