我利用flink处理kafka获取的string数据,将每一个流数据通过flatmap扁平化后提取其中的数据,并输出成tuole类型,再利用sink导出到postgresql中
时间: 2024-02-23 13:01:35 浏览: 18
可以参考以下代码实现:
```java
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer;
import org.apache.flink.streaming.connectors.kafka.FlinkKafkaProducer;
import org.apache.flink.streaming.util.serialization.SimpleStringSchema;
import org.apache.flink.util.Collector;
import java.util.Properties;
public class KafkaToPostgreSQL {
public static void main(String[] args) throws Exception {
// set up the execution environment
final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
// set up the Kafka consumer properties
Properties props = new Properties();
props.setProperty("bootstrap.servers", "localhost:9092");
props.setProperty("group.id", "test");
// create a Kafka consumer and get the input stream
FlinkKafkaConsumer<String> consumer = new FlinkKafkaConsumer<>("my-topic", new SimpleStringSchema(), props);
DataStream<String> input = env.addSource(consumer);
// parse the JSON strings and extract the desired fields
DataStream<Tuple2<String, Integer>> output = input.flatMap(new FlatMapFunction<String, Tuple2<String, Integer>>() {
private transient ObjectMapper jsonParser;
@Override
public void flatMap(String value, Collector<Tuple2<String, Integer>> out) throws Exception {
if (jsonParser == null) {
jsonParser = new ObjectMapper();
}
JsonNode jsonNode = jsonParser.readTree(value);
String field1 = jsonNode.get("field1").asText();
int field2 = jsonNode.get("field2").asInt();
out.collect(new Tuple2<>(field1, field2));
}
});
// write the output to PostgreSQL using a FlinkKafkaProducer
Properties producerProps = new Properties();
producerProps.setProperty("bootstrap.servers", "localhost:9092");
FlinkKafkaProducer<Tuple2<String, Integer>> producer = new FlinkKafkaProducer<>("my-output-topic", new MyTupleSerializationSchema("jdbc:postgresql://localhost:5432/mydb", "myuser", "mypassword"), producerProps, FlinkKafkaProducer.Semantic.EXACTLY_ONCE);
output.addSink(producer);
// execute the program
env.execute("Kafka to PostgreSQL");
}
}
```
其中,`MyTupleSerializationSchema` 是一个自定义的序列化器,用于将 `Tuple2<String, Integer>` 类型的数据写入到 PostgreSQL 中。你需要根据自己的实际情况实现该类。在上面的代码中,我使用了 FlinkKafkaProducer 将数据写回到 Kafka 中,你也可以直接使用 Flink JDBC connector 将数据写入到 PostgreSQL 中。