读取现有的Avro文件并发送到Kafka

Question

我有一个具有该模式的现有Avro文件。 我需要将文件发送给Producer。

以下是我编写的代码。

public class ProducerDataSample {

    public static void main(String[] args) {

        String topic = "my-topic";

        Schema.Parser parser = new Schema.Parser();
        Schema schema = parser.parse(AvroSchemaDefinitionLoader.fromFile("encounter.avsc").get());

            File file = new File("/home/hello.avro");
        try{
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        DatumWriter<GenericRecord> datumWriter = new GenericDatumWriter<GenericRecord>(schema);
        DataFileWriter<GenericRecord> dataFileWriter = new DataFileWriter<GenericRecord>(datumWriter);
        dataFileWriter.create(schema, outputStream);
        dataFileWriter.appendTo(file);
        dataFileWriter.close();
        System.out.println("Here comes the data: " + outputStream);



        // Start KAFKA publishing

        Properties props = new Properties();
        props.put("bootstrap.servers", "localhost:9092");
        props.put("serializer.class", "kafka.serializer.StringEncoder");
        props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
        props.put("value.serializer", "org.apache.kafka.common.serialization.ByteArraySerializer");

        KafkaProducer<String, byte[]> messageProducer = new KafkaProducer<String, byte[]>(props);
        ProducerRecord<String, byte[]> producerRecord = null;
        producerRecord = new ProducerRecord<String, byte[]>("m-topic","1",outputStream.toByteArray());
        messageProducer.send(producerRecord);
        messageProducer.close();
        }catch(Exception e){
            System.out.println("Error in sending to kafka");
            e.printStackTrace();
        }





    }
}

一旦执行此命令，就会收到错误消息：

Error in sending to kafka org.apache.avro.AvroRuntimeException: already open
at org.apache.avro.file.DataFileWriter.assertNotOpen(DataFileWriter.java:85) 
at org.apache.avro.file.DataFileWriter.appendTo(DataFileWriter.java:203)
at org.apache.avro.file.DataFileWriter.appendTo(DataFileWriter.java:193)
at ProducerDataSample.main(ProducerDataSample.java:51)

任何帮助。 谢谢。

Answer 1

您将不得不从avro文件中读取数据并将其序列化为bytes数组

如下代码片段所示

        final Schema schema = new Schema.Parser().parse(new File("sample.avsc"));            
        File file ="sample.avro"

        //read the avro file to GenericRecord
        final GenericDatumReader<GenericRecord> genericDatumReader = new GenericDatumReader<>(schema);
        final DataFileReader<GenericRecord> genericRecords = new DataFileReader<>(file, genericDatumReader);

        //serialize GenericRecords
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        DatumWriter<GenericRecord> writer = new GenericDatumWriter<GenericRecord>(schema);

        Encoder binaryEncoder = EncoderFactory.get().binaryEncoder(out, null);

        while (genericRecords.hasNext()) {
            writer.write(genericRecords.next(), binaryEncoder);
        }
        binaryEncoder.flush();
        out.close();
       //send out.toByteArray() to kakfa

Answer 2

我认为其他答案应该像这样，将个人记录作为Kafka事件发送。

注意：应该可以直接从Avro文件中获取架构，而不要拥有单独的AVSC文件。 在Avro项目中遵循以下代码

final Schema schema = new Schema.Parser().parse(new File("sample.avsc"));            
File file = new File("sample.avro");

//read the avro file to GenericRecord
final GenericDatumReader<GenericRecord> genericDatumReader = new GenericDatumReader<>(schema);
final DataFileReader<GenericRecord> genericRecords = new DataFileReader<>(file, genericDatumReader);

DatumWriter<GenericRecord> writer = new GenericDatumWriter<GenericRecord>(schema);

while (genericRecords.hasNext()) {
    //serialize GenericRecords
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    Encoder binaryEncoder = EncoderFactory.get().binaryEncoder(out, null);
    writer.write(genericRecords.next(), binaryEncoder);
    binaryEncoder.flush();
    out.close();

    // TODO: send out.toByteArray() to kafka
}

// TODO: kafkaProducer.flush();