I have a REST API which returns a JSON response as:
{
"channel" : "JHBHS"
}
and sometimes it returns:
{
"channel": {
"id": 12321,
"name": "Some channel"
}
}
I have a POJO like:
public class Event {
private String channel;
@JsonProperty("channel")
private Channel channelObj;
}
public class Channel {
private int id;
private String name;
}
So, is there a way (other than writing your own custom deserializer) in Jackson2 which will help me map channel
in JSON to String
type when it's a String
and Channel
type when it's a JSON Object?
Or in other words, is there a way in Jackson which maps by type
of the variable and not just by name
?
I can suggest you to use JsonNode like this:
class Event {
@JsonProperty("channel")
private JsonNode channelInternal;
private Channel channel;
private String channelStr;
/**
* Custom getter with channel parsing
* @return channel
*/
public Channel getChannel() {
if (channel == null && channelInternal != null) {
if (channelInternal.isObject()) {
int id = channelInternal.get("id").intValue();
String name = channelInternal.get("name").asText();
channel = new Channel(id, name);
}
}
return channel;
}
/**
* Custom getter with channel string parsing
* @return channel string
*/
public String getChannelStr() {
if (channelStr == null && channelInternal != null) {
if (channelInternal.isTextual()) {
channelStr = channelInternal.asText();
}
}
return channelStr;
}
}
or like this:
class Event {
private Channel channel;
private String channelStr;
@JsonSetter("channel")
public void setChannelInternal(JsonNode channelInternal) {
if (channelInternal != null) {
if (channelInternal.isTextual()) {
channelStr = channelInternal.asText();
} else if (channelInternal.isObject()) {
int id = channelInternal.get("id").intValue();
String name = channelInternal.get("name").asText();
channel = new Channel(id, name);
}
}
}
public Channel getChannel() {
return channel;
}
public String getChannelStr() {
return channelStr;
}
}
But I think using custom deserializer is more common.
Here is test code
public static void main(String[] args) throws IOException {
ObjectMapper objectMapper = new ObjectMapper();
String source1 = "{\n" +
" \"channel\" : \"JHBHS\"\n" +
"}";
String source2 = "{\n" +
" \"channel\": {\n" +
" \"id\": 12321,\n" +
" \"name\": \"Some channel\"\n" +
" }\n" +
"}";
//Test object parsing
Event result = objectMapper.readValue(source2, Event.class);
System.out.println(String.format("%s : %s", result.getChannel().getId(), result.getChannel().getName()));
//Test string parsing
result = objectMapper.readValue(source1, Event.class);
System.out.println(result.getChannelStr());
}
And the output:
12321 : Some channel
JHBHS
来源:https://stackoverflow.com/questions/37812973/deserializing-attributes-of-same-name-but-different-types-in-jackson