Deserializing byte array from json string

Question

I have Dto with field of byte array and json string, serialized with JSON.stringify and service, that should parse this string.

@Data
@NoArgsConstructor
@AllArgsConstructor
public class CompanyDto {

    private UUID id;
    private String name;
    private boolean isVerified;
    private String description;
    private byte[] fileData;
    private UUID accountId;
}

    @Override
    public CompanyDto parseCompanyDto(String s) {
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.registerModule(new Hibernate5Module());
        try {
            return objectMapper.readValue(s, CompanyDto.class);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
            return null;
        }
    }

If fileData in input string is null, this service works well, but it can't deserialize byte array from string, serialized on frontend. It fails with exeption:

com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `[B` out of START_OBJECT token
 at [Source: (String)"{"name":"testCompany","description":"test test test","fileData":{"0":255,"1":216,"2":255,"3":224,"4":0,"5":16,"6":74,"7":70,"8":73,"9":70,"10":0,"11":1,"12":1,"13":2,"14":0,"15":56,"16":0,"17":56,"18":0,"19":0,"20":255,"21":219,"22":0,"23":67,"24":0,"25":2,"26":2,"27":2,"28":2,"29":2,"30":1,"31":2,"32":2,"33":2,"34":2,"35":3,"36":2,"37":2,"38":3,"39":3,"40":6,"41":4,"42":3,"43":3,"44":3,"45":3,"46":7,"47":5,"48":5,"49":4,"50":6,"51":8,"52":7,"53":9,"54":8,"55":8,"56":7,"57":8,"58":8,"59":9,"60":"[truncated 25008 chars]; line: 1, column: 65] (through reference chain: edu.netcracker.jobdealer.dto.CompanyDto["fileData"])
    at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:59)
    at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1442)
    at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1216)
    at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1126)
    at com.fasterxml.jackson.databind.deser.std.PrimitiveArrayDeserializers.handleNonArray(PrimitiveArrayDeserializers.java:240)
    at com.fasterxml.jackson.databind.deser.std.PrimitiveArrayDeserializers$ByteDeser.deserialize(PrimitiveArrayDeserializers.java:498)
    at com.fasterxml.jackson.databind.deser.std.PrimitiveArrayDeserializers$ByteDeser.deserialize(PrimitiveArrayDeserializers.java:446)
    at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:129)
    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._readMapAndClose(ObjectMapper.java:4202)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3205)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3173)
    at service.impl.JsonServiceImpl.parseCompanyDto(JsonServiceImpl.java:51)

I tried to send fileData separately using URlSearchParams.append and it worked well, but it sounds like a dirty hack.

Can you say, what instance of [B means and how to parse it correctly?

Could you show example `JSON` payload you want to deserialise? — Michał Ziober, Dec 02 '19 at 07:44
`[B` is the type name for `byte[]` and is what you want. Why are you serializing as a bunch of quoted int values instead of as Base64? — chrylis -cautiouslyoptimistic-, Dec 02 '19 at 07:44
Possible duplicate of [how to deserialize / serialize byte array using Jackson and wrapper object](https://stackoverflow.com/questions/40993617/how-to-deserialize-serialize-byte-array-using-jackson-and-wrapper-object), maybe you can try the answer. — LHCHIN, Dec 02 '19 at 08:20
Michal, example of json in second line of stack trace. It can't print all, cause length of this json is near 17k symbols — schwarzkv, Dec 02 '19 at 11:17

score 3 · Accepted Answer · answered Dec 02 '19 at 08:06

3

Java can't serialize byte array. Use base64 or you can implement your own serializer/deserializer

answered Dec 02 '19 at 08:06

Bilguun Bayartsengel

194
1
9

thanks for an answer, i've changed format of receiving data to base64 and now it works well – schwarzkv Dec 02 '19 at 18:35

Deserializing byte array from json string

1 Answers1