Hi experts,
following previous discussions for including de/serializers in JSONB
along with adapters, here is proposal for interfaces in JSONB API:
public interface JsonbSerializer<T> {void serialize(T obj, JsonbGenerator generator, SerializationContext ctx);
}
public interface JsonbDeserializer<T> {T deserialize(JsonbParser parser, DeserializationContext ctx);
}
/** * Jsonb decorator for JSONP generator.Includes validation for
writing END_OBJECT / END_ARRAY checking level of closed JSON structure.
* Helper generator methods may be added here. */ public interface JsonbGeneratorextends JsonGenerator {
}
/** * Jsonb decorator for JSONP parser.Includes validation of cursor
position after leaving deserializer, alters hasNext() behavior. * Helper
parser methods may be added here. */ public interface JsonbParserextends JsonParser {
}
public interface SerializationContext {
/** * Serializes arbitrary object to JSON with JSONB, using current
{_at_link javax.json.stream.JsonGenerator} instance.*/ <T>void serialize(String key,T object);
/** * Checks if type is supported for conversion to string by JSONB.*/
boolean supportsConversion(Class<?> clazz);
/** * Converts string value into provided type. String value has to be
single JSON value, not a part * of a JSON document representing JSON
object / array.*/ <T> String convertDefault(T obj);
}
public interface DeserializationContext {
/** * Deserializes JSON stream into instance of provided class with
JSONB using {_at_link javax.json.stream.JsonParser}. * JsonParser cursor
have to be at KEY_NAME before START_OBJECT to call this method.*/ <T>T deserialize(Class<T> clazz);
/** * Similar as above for generic types.*/ <T>T deserialize(TypeInfo<T> typeInfo);
/** * Checks if type is supported for conversion from string by JSONB.*/
boolean supportsConversion(Class<?> toClass);
/** * Converts string value into provided type. String value has to be
single JSON value, not a part * of a JSON document representing JSON
object.*/ <T>T convertDefault(Class<T> toClass, String value);
}
JsonbParser / JsonbGenerator objects are supposed to decorate JSONP behavior.
For example in case of JsonParser hasNext() call may be altered to return false if currently deserialized object has ended in the stream. Helper methods (like nextKey(String), isKey(String), etc for json processing may be included here.
In addition to Generators/Parsers, (De)SerializationContexts are intended to provide JSONB functionality such as (de)serialization of arbitrary java types, conversion to/from string of known types such are Dates or Numbers.
We could also add some insight into introspected customization from JSONB annotations based on a Class and property name.
An example of how implementation of such (de)serializer may look:
public class CrateSerializerimplements JsonbSerializer<Crate> {
@Override public void serialize(Crate obj, JsonbGenerator generator, SerializationContext ctx) {
generator.write("crateStr","REPLACED");
ctx.serialize("crateInner", obj.crateInner);
ctx.serialize("crateInnerList", obj.crateInnerList);
generator.write("date-converted", dateValue);
}
}
public class CrateDeserializerimplements JsonbDeserializer<Crate> { @Override public Crate deserialize(JsonbParser jsonParser, DeserializationContext ctx) {
Crate crate =new Crate();
while (jsonParser.hasNext()) {
JsonParser.Event next = jsonParser.next();
if (next.equals(JsonParser.Event.KEY_NAME) && jsonParser.getString().equals("crateInner")) {
//invokes JSONB processing for a CrateInner as a root type with "shared"
instance of JsonParser //may invoke other serializer or adapter
instances inside crate.crateInner = ctx.deserialize(CrateInner.class);
next = jsonParser.next();
}
if (next.equals(JsonParser.Event.KEY_NAME) && jsonParser.getString().equals("crateInnerList")) {
//invokes JSONB processing for a List<CrateInner> as a root type with
"shared" instance of JsonParser //may invoke other serializer or adapter
instances inside crate.crateInnerList = ctx.deserialize(new TypeToken<List<CrateInner>>() {});
}
if (next.equals(JsonParser.Event.KEY_NAME) && jsonParser.getString().equals("date-converted")) {
jsonParser.next();
//don't have context of processing here, no annotation customizations
applied. Date converted = ctx.convertDefault(Date.class, jsonParser.getString());
crate.date = converted;
}
}
return crate;
}
}
@Romain, this is similar to what you have suggested first time.
In addition JsonbAdapters may be used to convert From / To JsonObject or JsonArray, but auto conversion between unknown JavaTypes and JsonStructure will not be supported, at least in first version of a spec.
WDYT?
Thanks,
Roman