Gson: serialization of dates in various formats

Question

I am using Gson and need to serialize a class with different date formats:

@TimeStampField(onlyDate = false)
private Timestamp datahora

@TimeStampField(onlyDate = true)
private Timestamp diaLimite

I wanted to take these annotations within my Jsonserializer and define the format of my date (yyyy/MM/dd or yyyy/MM/dd'T'12:30:00.0'Z')

Is it possible? Is there any alternative?

Answer 1

I made a Typeadapter for Timestamp, the problem is that I work with Timestamp for all date fields, but Webserservice is restricted to formats ("yyyy/MM/dd" or "yyyyyy/MM/dd’T'12:30:00.0'Z'"), the best way to circumvent this was to create a class that extends Timestamp "Datestamp" and create a Adapter for her. Hence the fields that I serializo only with date are of type Datestamp

Answer 2

Before you start, I suggest you use the correct format ISO8601, that is 2018-07-11T23:15:15.600Z.

To do the procedure Voce wants Voce will have to implement com.google.gson.TypeAdapter<Timestamp>

Example:

public static class MyDateTypeAdapter extends TypeAdapter< Timestamp > {
    private final SimpleDateFormat dataEhora = new SimpleDateFormat( "yyyy/MM/dd'T'hh:mm:ss.SSS" );
    private final SimpleDateFormat data = new SimpleDateFormat( "yyyy/MM/dd" );

    @Override
    public void write( JsonWriter out, Timestamp value ) throws IOException {
        if ( value == null ) {
            out.nullValue();
        } else {
            if ( value.getNanos() == 0 && value.getSeconds() == 0 && value.getMinutes() == 0 && value.getHours() == 0 ) {
                out.value( this.data.format( value ) );
            } else {
                out.value( this.dataEhora.format( value ) );
            }
        }
    }

    @Override
    public Timestamp read( JsonReader in ) throws IOException {
        if ( in != null ) {
            String dataString = in.nextString();
            final SimpleDateFormat format;
            if ( dataString.length() == 10 ) {
                format = this.data;
            } else {
                format = this.dataEhora;
            }
            Date parsedDate;
            try {
                parsedDate = format.parse( dataString );
                return new Timestamp( parsedDate.getTime() );
            } catch ( ParseException e ) {
                return null;
            }

        } else {
            return null;
        }
    }
}

Now you must create the instance of your Gson setting the created Adapter, see below:

class Exemplo {
    Timestamp dataComHora;
    Timestamp data;
}

class Teste {

    public static void main( String[] args ) {
        Gson gson = new GsonBuilder().registerTypeAdapter( Timestamp.class, new MyDateTypeAdapter() ).create();
        String json = "{\"dataComHora\":\"2018/07/11T11:30:13.795\",\"data\":\"2018/08/11\"}";

        System.out.println( "entrada: " + json );
        Exemplo exemplo = gson.fromJson( json, Exemplo.class );
        System.out.println( "saida: " + gson.toJson( exemplo ) );
    }
}