FlatResponseCsvProvider.java

package com.flipkart.foxtrot.server.providers;

import com.flipkart.foxtrot.sql.responseprocessors.model.FlatRepresentation;

import javax.ws.rs.Produces;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.MessageBodyWriter;
import javax.ws.rs.ext.Provider;
import java.io.IOException;
import java.io.OutputStream;
import java.io.StringWriter;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;

@Provider
@Produces(FoxtrotExtraMediaType.TEXT_CSV)
public class FlatResponseCsvProvider implements MessageBodyWriter<FlatRepresentation> {

    @Override
    public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        return type == FlatRepresentation.class && mediaType.toString().equals(FoxtrotExtraMediaType.TEXT_CSV);
    }

    @Override
    public long getSize(FlatRepresentation response, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        return -1;
    }

    @Override
    public void writeTo(FlatRepresentation response, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType, MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream) throws IOException, WebApplicationException {
        if(null == response) {
            entityStream.write("No records found matching the specified criterion".getBytes());
            return;
        }
        StringWriter dataBuffer = new StringWriter();
        FlatToCsvConverter.convert(response, dataBuffer);
        entityStream.write(dataBuffer.toString().getBytes());
    }


}