paio di opzioni diverse in base alla risposta di Cirillo:
serializzatore personalizzata con una scorciatoia:
public static class Sample
{
String firstName = "John";
String lastName = "Doe";
public String getFullName()
{
return firstName + " " + lastName;
}
}
public static class SampleSerializer implements JsonSerializer<Sample>
{
public JsonElement serialize(Sample src, Type typeOfSrc, JsonSerializationContext context)
{
JsonObject tree = (JsonObject)new Gson().toJsonTree(src);
tree.addProperty("fullName", src.getFullName());
return tree;
}
}
public static void main(String[] args) throws Exception
{
GsonBuilder gson = new GsonBuilder();
gson.registerTypeAdapter(Sample.class, new SampleSerializer());
Gson parser = gson.create();
System.out.println(parser.toJson(new Sample()));
}
OPPURE annotazione serializzatore basato
public static class Sample
{
String firstName = "John";
String lastName = "Doe";
@ExposeMethod
public String getFullName()
{
return firstName + " " + lastName;
}
}
public static class MethodSerializer implements JsonSerializer<Object>
{
public JsonElement serialize(Object src, Type typeOfSrc, JsonSerializationContext context)
{
Gson gson = new Gson();
JsonObject tree = (JsonObject)gson.toJsonTree(src);
try
{
PropertyDescriptor[] properties = Introspector.getBeanInfo(src.getClass()).getPropertyDescriptors();
for (PropertyDescriptor property : properties)
{
if (property.getReadMethod().getAnnotation(ExposeMethod.class) != null)
{
Object result = property.getReadMethod().invoke(src, (Object[])null);
tree.add(property.getName(), gson.toJsonTree(result));
}
}
}
catch (Exception ex)
{
ex.printStackTrace();
}
return tree;
}
}
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD) //can use in method only.
public static @interface ExposeMethod {}
public static void main(String[] args) throws Exception
{
GsonBuilder gson = new GsonBuilder();
gson.registerTypeAdapter(Sample.class, new MethodSerializer());
Gson parser = gson.create();
System.out.println(parser.toJson(new Sample()));
}
Questo funziona solo se v'è una sola classe, senza alcun riferimento a qualsiasi altro oggetto. Se si dispone ad esempio di un elenco, il metodo non funzionerebbe. –
Martin