如何在java中使用dataflow text io动态目的地

import org.apache.beam.sdk.Pipeline;
import org.apache.beam.sdk.io.TextIO;
import org.apache.beam.sdk.io.fs.EmptyMatchTreatment;
import org.apache.beam.sdk.io.fs.MatchResult;
import org.apache.beam.sdk.io.fs.ResourceId;
import org.apache.beam.sdk.options.PipelineOptionsFactory;
import org.apache.beam.sdk.transforms.DoFn;
import org.apache.beam.sdk.transforms.ParDo;
import org.apache.beam.sdk.transforms.SimpleFunction;
import org.apache.beam.sdk.values.KV;
import org.apache.beam.sdk.values.PCollection;
import org.apache.beam.sdk.values.PDone;
import org.apache.beam.sdk.values.ValueInSingleWindow;

import java.nio.channels.Channels;
import java.nio.channels.WritableByteChannel;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;

public class DynamicDestinationExample {

    public static void main(String[] args) {
        // 创建Pipeline
        Pipeline pipeline = Pipeline.create(PipelineOptionsFactory.create());

        // 定义数据源
        PCollection<String> input = pipeline.apply(TextIO.read().from("gs://bucket/input.txt"));

        // 定义数据处理逻辑
        PCollection<KV<String, String>> processedData = input.apply(ParDo.of(new MyDoFn()));

        // 定义动态目的地
        DynamicDestinations<String, String> dynamicDestinations = new MyDynamicDestinations();

        // 写入数据
        PDone output = processedData.apply(TextIO.writeDynamic()
                .to(dynamicDestinations)
                .withTempDirectory("gs://bucket/temp")
                .withDestinationCoder(StringUtf8Coder.of())
                .withNumShards(1));

        // 运行Pipeline
        pipeline.run();
    }

    // 自定义数据处理函数
    static class MyDoFn extends DoFn<String, KV<String, String>> {
        @ProcessElement
        public void processElement(ProcessContext c) {
            String element = c.element();
            // 数据处理逻辑
            // ...
            c.output(KV.of("key", "value"));
        }
    }

    // 自定义动态目的地
    static class MyDynamicDestinations extends DynamicDestinations<String, String> {
        @Override
        public String getDestination(ValueInSingleWindow<String> element) {
            // 根据数据的内容动态确定目的地
            // ...
            return "gs://bucket/output.txt";
        }

        @Override
        public List<String> getInitialDestinationNames(int numShards) {
            // 初始化目的地名称列表
            List<String> destinationNames = new ArrayList<>();
            for (int i = 0; i < numShards; i++) {
                destinationNames.add("output-" + i + ".txt");
            }
            return destinationNames;
        }

        @Override
        public Coder<String> getDestinationCoder() {
            return StringUtf8Coder.of();
        }
    }
}