Unidentified token exception handling in user json with Jackson

Question

I am trying to use the Jackson json parser (v2.5.2) to parse a custom json document that is not true json, and I cannot figure out how to make it work. I have a json document that might look like this:

{ "test": { "one":"oneThing", "two": nonStandardThing(), "three": true } } 

I want to use ObjectMapper to map this to java.util.Map , and I would like nonStandardThing() added as a String value on my map for key two .

When I run this through ObjectMapper.readValue(json, Map.class) , I get an exception:

 com.fasterxml.jackson.core.JsonParseException: Unrecognized token 'nonStandardThing': was expecting 'null', 'true', 'false' or NaN at [Source: { "test":{"test1":nonStandardThing(),"test2":"two"}}; line: 1, column: 35] at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:1487) at com.fasterxml.jackson.core.base.ParserMinimalBase._reportError(ParserMinimalBase.java:518) at com.fasterxml.jackson.core.json.ReaderBasedJsonParser._reportInvalidToken(ReaderBasedJsonParser.java:2300) at com.fasterxml.jackson.core.json.ReaderBasedJsonParser._reportInvalidToken(ReaderBasedJsonParser.java:2277) 

I tried registering DeserializationProblemHandler using ObjectMapper , but it is never called when this problem occurs.

Here is an example application that shows what I tried:

 import com.fasterxml.jackson.core.JsonParser; import com.fasterxml.jackson.core.JsonProcessingException; import com.fasterxml.jackson.databind.DeserializationContext; import com.fasterxml.jackson.databind.JsonDeserializer; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.deser.DeserializationProblemHandler; import java.io.IOException; import java.util.Map; import java.util.logging.Level; import java.util.logging.Logger; public class JacksonDeserializerTest { private Logger log = Logger.getLogger(JacksonDeserializerTest.class.getName()); public JacksonDeserializerTest() { String validJson = "{ \"test\":{\"test1\":\"one\",\"test2\":\"two\"}}"; String invalidJson = "{ \"test\":{\"test1\":nonStandardThing(),\"test2\":\"two\"}}"; ObjectMapper mapper = new ObjectMapper(); mapper.addHandler(new DeserializationProblemHandler() { @Override public boolean handleUnknownProperty(DeserializationContext dc, JsonParser jp, JsonDeserializer<?> jd, Object bean, String property) throws IOException, JsonProcessingException { System.out.println("Handling unknown property: " + property); return false; } }); try { log.log(Level.INFO, "Valid json looks like: {0}", mapper.readValue( validJson, Map.class).toString()); log.log(Level.INFO, "Invalid json looks like: {0}", mapper.readValue(invalidJson, Map.class).toString()); } catch (IOException ex) { log.log(Level.SEVERE, "Error parsing json", ex); } } public static void main(String[] args) { JacksonDeserializerTest test = new JacksonDeserializerTest(); } } 

The result is as follows:

 Apr 24, 2015 1:40:27 PM net.acesinc.data.json.generator.jackson.JacksonDeserializerTest <init> INFO: Valid json looks like: {test={test1=one, test2=two}} Apr 24, 2015 1:40:27 PM net.acesinc.data.json.generator.jackson.JacksonDeserializerTest <init> SEVERE: Error parsing json com.fasterxml.jackson.core.JsonParseException: Unrecognized token 'nonStandardThing': was expecting 'null', 'true', 'false' or NaN at [Source: { "test":{"test1":nonStandardThing(),"test2":"two"}}; line: 1, column: 35] at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:1487) at com.fasterxml.jackson.core.base.ParserMinimalBase._reportError(ParserMinimalBase.java:518) at com.fasterxml.jackson.core.json.ReaderBasedJsonParser._reportInvalidToken(ReaderBasedJsonParser.java:2300) at com.fasterxml.jackson.core.json.ReaderBasedJsonParser._reportInvalidToken(ReaderBasedJsonParser.java:2277) at com.fasterxml.jackson.core.json.ReaderBasedJsonParser._matchToken(ReaderBasedJsonParser.java:2129) 

Can anyone point out why Handler is never called? Or, if there is a better analysis of this custom json document (jackson or not ...), let me know.

Answer 1

The handler is not called because the invalid part is not a property ( "two" ), but a value ( nonStandardThing() ).

The obvious way to handle this is to pass nonStandardThing() as a String , i.e. rewrite the JSON document as

 { "test": { "one":"oneThing", "two": "nonStandardThing()", "three": true } } 

If this is not possible, there is nothing to do. Using a custom Jackson Deserializer is only useful for properties, not values.

Answer 2

The content, to which you, unfortunately, does not apply to JSON, so that you do not actually have a JSON document, but perhaps a serialization of the Javascript object. All String values ​​MUST be enclosed in double quotation marks in JSON.

Jackson does not support direct reading of such content, but it can be read using a YAML parser such as SnakeYAML. Jackson also has a YAML data format module at https://github.com/FasterXML/jackson-dataformat-yaml/ so you can use it. Given that YAML (basically!) Is a superset of JSON, it can probably do what you want.

Answer 3

I am trying to make a Post Rest call to an API web service, but I get an unrecognized token when I try to send information to a web service.

The web service API is @http: /// takeParams? DeviceId = 12345 & cpName = Metropolitan + Plant & personNo = 20335 & fullName = Adams% 2C + Eliza & punchTS = 2019-10-12T13% 3A57% 3A47.149721045 & pcName = LMP casino

And the error I get is as follows

com.fasterxml.jackson.core.JsonParseException: unrecognized Metro token: expected (true, false or zero) in [Source: (String) Embleado Metropolitan Plant: Adams, Eliza (20335) Fetch: 2019-10-12T20: 57: 35.446584274 LMP-Casino Desayuno "; row: 2, column: 13] :: error parsing the response

Can you please advise someone?