我按照这个链接创建了一个模板，它构建了一个梁管道来读取kafkaio的内容。但我总是遇到“不兼容类型：org.apache.beam.sdk.options.valueprovider无法转换为java.lang.string”。导致错误的是“.WithBootsTapServers（options.getkafkaserver（））”行。beam版本是2.9.0，这是我代码的一部分。

public interface Options extends PipelineOptions {
    @Description("Kafka server")
    @Required
    ValueProvider<String> getKafkaServer();

    void setKafkaServer(ValueProvider<String> value);

    @Description("Topic to read from")
    @Required
    ValueProvider<String> getInputTopic();

    void setInputTopic(ValueProvider<String> value);

    @Description("Topic to write to")
    @Required
    ValueProvider<String> getOutputTopic();

    void setOutputTopic(ValueProvider<String> value);

    @Description("File path to write to")
    @Required
    ValueProvider<String> getOutput();

    void setOutput(ValueProvider<String> value);
}

public static void main(String[] args) {
    Options options = PipelineOptionsFactory.fromArgs(args).withValidation().as(Options.class);
    Pipeline p = Pipeline.create(options);

    PCollection<String> processedData = p.apply(KafkaIO.<Long, String>read()
            .withBootstrapServers(options.getKafkaServer())
            .withTopic(options.getInputTopic())
            .withKeyDeserializer(LongDeserializer.class)
            .withValueDeserializer(StringDeserializer.class)
            .withoutMetadata() 
    )

下面是我如何运行代码：

mvn compile exec:java \
-Dexec.mainClass=${MyClass} \
-Pdataflow-runner -Dexec.args=" \
--project=${MyClass} \
--stagingLocation=gs://${MyBucket}/staging \
--tempLocation=gs://${MyBucket}/temp \
--templateLocation=gs://${MyBucket}/templates/${MyClass} \
--runner=DataflowRunner"