flink将KafkaSource<ObjectNode>转化为DataStream<RowData>

要将Flink的KafkaSource<ObjectNode>转换为DataStream<RowData>，需要进行以下步骤：

1. 创建一个DeserializationSchema，将ObjectNode反序列化为RowData对象。例如，可以使用JsonRowDataDeserializationSchema。

2. 使用KafkaSource从Kafka主题中读取ObjectNode对象，并使用上一步中创建的DeserializationSchema将其转换为RowData对象。

3. 在DataStream上应用map操作，将RowData对象转换为所需的格式。

下面是一个示例代码，使用JsonRowDataDeserializationSchema将ObjectNode转换为RowData，然后将其转换为Tuple2<String, String>：

import org.apache.flink.api.common.serialization.DeserializationSchema;
import org.apache.flink.api.common.serialization.SimpleStringSchema;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.api.java.typeutils.RowTypeInfo;
import org.apache.flink.formats.json.JsonRowDataDeserializationSchema;
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.table.api.TableSchema;
import org.apache.flink.table.api.bridge.java.StreamTableEnvironment;
import org.apache.flink.table.types.logical.RowType;
import org.apache.flink.types.Row;

import com.fasterxml.jackson.databind.node.ObjectNode;

import java.util.Properties;

public class KafkaObjectNodeToRowData {

    public static void main(String[] args) throws Exception {
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        StreamTableEnvironment tEnv = StreamTableEnvironment.create(env);

        Properties properties = new Properties();
        properties.setProperty("bootstrap.servers", "localhost:9092");
        properties.setProperty("group.id", "test");

        // create a DeserializationSchema to deserialize ObjectNode to RowData
        RowType rowType = new RowType(
            new TableSchema.Builder()
                .field("id", DataTypes.BIGINT())
                .field("name", DataTypes.STRING())
                .build().toRowDataType().getChildren());
        DeserializationSchema<RowData> deserializationSchema = new JsonRowDataDeserializationSchema(rowType);

        // create a FlinkKafkaConsumer to read ObjectNode from Kafka
        FlinkKafkaConsumer<ObjectNode> kafkaConsumer = new FlinkKafkaConsumer<>("my-topic", deserializationSchema, properties);

        // read from Kafka and convert ObjectNode to RowData
        DataStream<RowData> rowDataStream = env.addSource(kafkaConsumer)
            .map(objectNode -> {
                // convert ObjectNode to RowData
                Row row = new Row(objectNode.size());
                for (int i = 0; i < objectNode.size(); i++) {
                    row.setField(i, objectNode.get(i).asText());
                }
                return row;
            })
            .returns(new RowTypeInfo(rowType.getFields().stream().map(RowType.RowField::getType).toArray(TypeInformation[]::new), rowType.getFieldNames().toArray(new String[0])));

        // convert RowData to Tuple2<String, String>
        DataStream<Tuple2<String, String>> tupleStream = rowDataStream
            .map(rowData -> Tuple2.of(rowData.getField(0).toString(), rowData.getField(1).toString()))
            .returns(Types.TUPLE(Types.STRING, Types.STRING));

        // do something with the tupleStream
        tupleStream.print();

        env.execute("KafkaObjectNodeToRowData");
    }
}