ReflectionTest.java

import org.apache.avro.Schema;
import org.apache.avro.generic.GenericDatumWriter;
import org.apache.avro.generic.GenericRecord;
import org.apache.avro.generic.GenericRecordBuilder;
import org.apache.avro.io.Decoder;
import org.apache.avro.io.DecoderFactory;
import org.apache.avro.io.Encoder;
import org.apache.avro.io.EncoderFactory;
import org.apache.avro.reflect.Nullable;
import org.apache.avro.reflect.ReflectData;
import org.apache.avro.reflect.ReflectDatumReader;
import org.junit.Test;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

import static org.junit.Assert.assertEquals;

public class ReflectionTest {
    public static class DifferentUser {

        @Nullable
        private String name;

        @Nullable
        private int favoriteNumber;

        @Nullable
        private String favoriteColor;

        public DifferentUser() {}

        public DifferentUser(String favoriteColor, int favoriteNumber, String name) {
            this.favoriteColor = favoriteColor;
            this.favoriteNumber = favoriteNumber;
            this.name = name;
        }

        public String getFavoriteColor() {
            return favoriteColor;
        }

        public void setFavoriteColor(String favoriteColor) {
            this.favoriteColor = favoriteColor;
        }

        public int getFavoriteNumber() {
            return favoriteNumber;
        }

        public void setFavoriteNumber(int favoriteNumber) {
            this.favoriteNumber = favoriteNumber;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }
    }

    @Test
    public void TestReflection() throws IOException {
        Schema schema = ReflectData.get().getSchema(DifferentUser.class);

        System.out.println("schema = " + schema.toString(true));

        GenericRecord gr = new GenericRecordBuilder(schema)
                .set("name", "joe")
                .set("favoriteNumber", 42)
                .set("favoriteColor", "blue")
                .build();

        GenericDatumWriter<GenericRecord> gdw = new GenericDatumWriter<>(schema);
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        Encoder encoder = EncoderFactory.get().binaryEncoder(baos, null);
        gdw.write(gr, encoder);
        encoder.flush();


        ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
        Decoder decoder = DecoderFactory.get().binaryDecoder(bais, null);

        ReflectDatumReader<DifferentUser> rdr = new ReflectDatumReader<>(DifferentUser.class);
        DifferentUser differentUser = rdr.read(null, decoder);
        assertEquals("joe", differentUser.getName());
        assertEquals(42, differentUser.getFavoriteNumber());
        assertEquals("blue", differentUser.getFavoriteColor());
    }

}