Avro Example 3 — Use Enum

In this example, we’ll use Enum and see how we can work with it.

customer.avsc

{
     "type": "record",
     "namespace": "com.example.generated.model",
     "name": "Customer",
     "fields": [
       { "name": "first_name", "type": "string", "doc": "First Name of Customer" },
       { "name": "last_name", "type": "string", "doc": "Last Name of Customer" },
       { "name": "age", "type": "int", "doc": "Age at the time of registration" },
       { "name": "height", "type": "float", "doc": "Height at the time of registration in cm" },
       { "name": "weight", "type": "float", "doc": "Weight at the time of registration in kg" },
       { "name": "automated_email", "type": "boolean", "default": true, "doc": "Field indicating if the user is enrolled in marketing emails" },
       { "name":"address", "type": "Address"},
       { "name":"Languages", "type": { "type": "enum", "name": "Languages", "symbols": ["English", "Hindi", "Marathi", "Spanish"]}}
     ]
}

address.avsc

{
  "name":"Address",
  "namespace": "com.example.generated.model",
  "type": "record",
  "fields": [
    {
      "name":"addressLine1",
      "type": "string"
    },
    {
      "name":"city",
      "type": "string"
    },
    {
      "name":"state_province",
      "type": "string"
    },
    {
      "name":"country",
      "type": "string",
      "default": "USA"
    },
    {
      "name":"zip",
      "type": "string"
    }
  ]
}

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>avro-demo-1</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>avro-demo-1</name>
    <url>http://maven.apache.org</url>

    <properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <repositories>
        <repository>
            <id>confluent</id>
            <name>Confluent</name>
            <url>https://packages.confluent.io/maven/</url>
        </repository>
    </repositories>

    <dependencies>
        <dependency>
            <groupId>org.apache.avro</groupId>
            <artifactId>avro</artifactId>
            <version>1.10.1</version>
        </dependency>
        <dependency>
            <groupId>com.github.javafaker</groupId>
            <artifactId>javafaker</artifactId>
            <version>1.0.2</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <!-- Maven Compiler Plugin-->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.0</version>
                <configuration>
                    <source>${java.version}</source>
                    <target>${java.version}</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.avro</groupId>
                <artifactId>avro-maven-plugin</artifactId>
                <version>1.9.2</version>
                <executions>
                    <execution>
                        <phase>generate-sources</phase>
                        <goals>
                            <goal>schema</goal>
                        </goals>
                        <configuration>
                            <sourceDirectory>${project.basedir}/src/main/avro/</sourceDirectory>
                            <outputDirectory>${project.basedir}/src/main/java/</outputDirectory>
                            <imports>
                                <import>${project.basedir}/src/main/avro/address.avsc</import>
                                <import>${project.basedir}/src/main/avro/customer.avsc</import>
                            </imports>
                            <enableDecimalLogicalType>true</enableDecimalLogicalType>
                            <customConversions>org.apache.avro.Conversions$UUIDConversion</customConversions>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

MainApp.java

package com.example.specific;

import com.example.generated.model.Address;
import com.example.generated.model.Customer;
import com.example.generated.model.Languages;
import org.apache.avro.file.DataFileReader;
import org.apache.avro.file.DataFileWriter;
import org.apache.avro.io.DatumReader;
import org.apache.avro.io.DatumWriter;
import org.apache.avro.specific.SpecificDatumReader;
import org.apache.avro.specific.SpecificDatumWriter;

import java.io.File;
import java.io.IOException;

public class SpecificRecordExamples {

    public static void main(String[] args) {
        Address.Builder addressBuilder = Address.newBuilder();
        addressBuilder.setAddressLine1("Main  Line");
        addressBuilder.setCity("Achalpur");
        addressBuilder.setCountry("IND");
        addressBuilder.setZip("444805");
        addressBuilder.setStateProvince("MH");

        Customer.Builder customerBuilder = Customer.newBuilder();
        customerBuilder.setAge(30);
        customerBuilder.setFirstName("Harshita");
        customerBuilder.setLastName("Dekate");
        customerBuilder.setAutomatedEmail(true);
        customerBuilder.setHeight(180f);
        customerBuilder.setWeight(70f);
        customerBuilder.setAddress(addressBuilder.build());
        customerBuilder.setLanguages(Languages.English);

        Customer customer = customerBuilder.build();
        System.out.println(customer.toString());

        // write it out to a file
        final DatumWriter<Customer> datumWriter = new SpecificDatumWriter<>(Customer.class);

        try (DataFileWriter<Customer> dataFileWriter = new DataFileWriter<>(datumWriter)) {
            dataFileWriter.create(customer.getSchema(), new File("customer-specific.avro"));
            dataFileWriter.append(customer);
            System.out.println("successfully wrote customer-specific.avro");
        } catch (IOException e){
            e.printStackTrace();
        }


        // read it from a file
        final File file = new File("customer-specific.avro");
        final DatumReader<Customer> datumReader = new SpecificDatumReader<>(Customer.class);
        final DataFileReader<Customer> dataFileReader;
        try {
            System.out.println("\nReading our specific record");
            dataFileReader = new DataFileReader<>(file, datumReader);
            while (dataFileReader.hasNext()) {
                Customer readCustomer = dataFileReader.next();
                System.out.println(readCustomer.toString());
                System.out.println("First name: " + readCustomer.getFirstName());
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Output —

{“first_name”: “Harshita”, “last_name”: “Dekate”, “age”: 30, “height”: 180.0, “weight”: 70.0, “automated_email”: true, “address”: {“addressLine1”: “Main Line”, “city”: “Achalpur”, “state_province”: “MH”, “country”: “IND”, “zip”: “444805”}, “Languages”: “English”}
successfully wrote customer-specific.avro

Reading our specific record
{“first_name”: “Harshita”, “last_name”: “Dekate”, “age”: 30, “height”: 180.0, “weight”: 70.0, “automated_email”: true, “address”: {“addressLine1”: “Main Line”, “city”: “Achalpur”, “state_province”: “MH”, “country”: “IND”, “zip”: “444805”}, “Languages”: “English”}
First name: Harshita