confluent提供了以下示例：

String key = "key1";
String userSchema = "{\"type\":\"record\"," +
                "\"name\":\"myrecord\"," +
                "\"fields\":[{\"name\":\"f1\",\"type\":\"string\"}]}";
Schema.Parser parser = new Schema.Parser();
Schema schema = parser.parse(userSchema);
GenericRecord avroRecord = new GenericData.Record(schema);
avroRecord.put("f1", "value1");
ProducerRecord<Object, Object> record = new ProducerRecord<>("topic1", key, avroRecord);
try {
  producer.send(record);
} catch(SerializationException e) {
  // may need to do something with it
}

有没有什么方法可以直接从schema注册表（如果已经存在）中获取producer的userschema，而不是硬编码？