The input stream I am parsing with Jackson contains latitude and longitude values such as here:
{
"name": "product 23",
"latitude": "52,48264",
"longitude": "13,31822"
}
For some reason the server uses commas as the decimal separator which produces an InvalidFormatException
. Since I cannot change the server output format I would like to teach Jackson's ObjectMapper
to handle those cases. Here is the relevant code:
public static Object getProducts(final String inputStream) {
ObjectMapper objectMapper = new ObjectMapper();
try {
return objectMapper.readValue(inputStream,
new TypeReference<Product>() {}
);
} catch (UnrecognizedPropertyException e) {
e.printStackTrace();
} catch (InvalidFormatException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (JsonParseException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
And here is the POJO:
import com.fasterxml.jackson.annotation.JsonProperty;
public class Product {
@JsonProperty("name")
public String name;
@JsonProperty("latitude")
public float latitude;
@JsonProperty("longitude")
public float longitude;
}
How can I tell Jackson that those coordinate values come with a German locale?
I suppose a custom deserializer for the specific fields as discussed here would be the way to go. I drafted this:
public class GermanFloatDeserializer extends JsonDeserializer<Float> {
@Override
public Float deserialize(JsonParser parser, DeserializationContext context)
throws IOException {
// TODO Do some comma magic
return floatValue;
}
}
Then the POJO would look like this:
import com.fasterxml.jackson.annotation.JsonProperty;
public class Product {
@JsonProperty("name")
public String name;
@JsonDeserialize(using = GermanFloatDeserializer.class, as = Float.class)
@JsonProperty("latitude")
public float latitude;
@JsonDeserialize(using = GermanFloatDeserializer.class, as = Float.class)
@JsonProperty("longitude")
public float longitude;
}
I came up with the following solution:
public class FlexibleFloatDeserializer extends JsonDeserializer<Float> {
@Override
public Float deserialize(JsonParser parser, DeserializationContext context)
throws IOException {
String floatString = parser.getText();
if (floatString.contains(",")) {
floatString = floatString.replace(",", ".");
}
return Float.valueOf(floatString);
}
}
...
public class Product {
@JsonProperty("name")
public String name;
@JsonDeserialize(using = FlexibleFloatDeserializer.class)
@JsonProperty("latitude")
public float latitude;
@JsonDeserialize(using = FlexibleFloatDeserializer.class)
@JsonProperty("longitude")
public float longitude;
}
Still I wonder why I it does not work when I specify the return value class as as = Float.class
as can be found in the documentation of JsonDeserialize
. It reads as if I am supposed to use one or the other but not both. Whatsoever, the docs also claim that as =
will be ignored when using =
is defined:
if using() is also used it has precedence (since it directly specified deserializer, whereas this would only be used to locate the deserializer) and value of this annotation property is ignored.