T - type for which the serializer is being registered. It is possible that a serializer
may be asked to serialize a specific generic type of the T.public interface JsonSerializer<T>
GsonBuilder.registerTypeAdapter(Type, Object).
Let us look at example where defining a serializer will be useful. The Id class
defined below has two fields: clazz and value.
public class Id<T> {
private final Class<T> clazz;
private final long value;
public Id(Class<T> clazz, long value) {
this.clazz = clazz;
this.value = value;
}
public long getValue() {
return value;
}
}
The default serialization of Id(com.foo.MyObject.class, 20L) will be
{"clazz":com.foo.MyObject,"value":20}. Suppose, you just want the output to be
the value instead, which is 20 in this case. You can achieve that by writing a custom
serializer:
class IdSerializer implements JsonSerializer<Id>() {
public JsonElement serialize(Id id, Type typeOfId, JsonSerializationContext context) {
return new JsonPrimitive(id.getValue());
}
}
You will also need to register IdSerializer with Gson as follows:
Gson gson = new GsonBuilder().registerTypeAdapter(Id.class, new IdSerializer()).create();
New applications should prefer TypeAdapter, whose streaming API
is more efficient than this interface's tree API.
| Modifier and Type | Method and Description |
|---|---|
JsonElement |
serialize(T src,
java.lang.reflect.Type typeOfSrc,
JsonSerializationContext context)
Gson invokes this call-back method during serialization when it encounters a field of the
specified type.
|
JsonElement serialize(T src, java.lang.reflect.Type typeOfSrc, JsonSerializationContext context)
In the implementation of this call-back method, you should consider invoking
JsonSerializationContext.serialize(Object, Type) method to create JsonElements for any
non-trivial field of the src object. However, you should never invoke it on the
src object itself since that will cause an infinite loop (Gson will call your
call-back method again).
src - the object that needs to be converted to Json.typeOfSrc - the actual type (fully genericized version) of the source object.Copyright © 2018. All Rights Reserved.