在运行时使用ValueProviders为SpannerIO分配表和列,可以通过以下步骤实现:
- 导入所需的依赖项:import org.apache.beam.sdk.options.ValueProvider;
import org.apache.beam.sdk.transforms.Create;
import org.apache.beam.sdk.transforms.DoFn;
import org.apache.beam.sdk.transforms.ParDo;
import org.apache.beam.sdk.transforms.SerializableFunction;
import org.apache.beam.sdk.transforms.SimpleFunction;
import org.apache.beam.sdk.transforms.Values;
import org.apache.beam.sdk.transforms.View;
import org.apache.beam.sdk.values.KV;
import org.apache.beam.sdk.values.PCollection;
import org.apache.beam.sdk.values.PCollectionView;
import org.apache.beam.sdk.values.PDone;
import org.apache.beam.sdk.values.TupleTag;
import org.apache.beam.sdk.values.TypeDescriptors;
import org.apache.beam.sdk.io.gcp.spanner.SpannerIO;
import org.apache.beam.sdk.io.gcp.spanner.SpannerConfig;
import org.apache.beam.sdk.io.gcp.spanner.Transaction;
import org.apache.beam.sdk.io.gcp.spanner.TransactionRunner;
import org.apache.beam.sdk.io.gcp.spanner.TransactionRunner.TransactionCallable;
import org.apache.beam.sdk.io.gcp.spanner.TransactionRunnerImpl;
import org.apache.beam.sdk.io.gcp.spanner.TransactionRunner.TransactionCallable;
import org.apache.beam.sdk.io.gcp.spanner.TransactionRunnerImpl;
- 创建一个ValueProvider来获取表名和列名:ValueProvider<String> tableNameProvider = options.getTableNameProvider();
ValueProvider<String> columnNameProvider = options.getColumnNameProvider();
- 创建一个DoFn来处理SpannerIO操作:public static class SpannerIOFn extends DoFn<String, Void> {
private final ValueProvider<String> tableNameProvider;
private final ValueProvider<String> columnNameProvider;
public SpannerIOFn(ValueProvider<String> tableNameProvider, ValueProvider<String> columnNameProvider) {
this.tableNameProvider = tableNameProvider;
this.columnNameProvider = columnNameProvider;
}
@ProcessElement
public void processElement(ProcessContext c) {
String tableName = tableNameProvider.get();
String columnName = columnNameProvider.get();
// 在这里执行SpannerIO操作,使用tableName和columnName
// 例如:SpannerIO.write().to(tableName).withColumn(columnName).build();
}
}
- 在主管道中使用ValueProvider创建SpannerIOFn实例,并将其应用于PCollection:PCollection<String> input = ...; // 输入数据
PCollectionView<String> tableNameView = input.apply(View.asSingleton());
PCollectionView<String> columnNameView = input.apply(View.asSingleton());
PCollection<Void> output = input.apply(ParDo.of(new SpannerIOFn(tableNameView, columnNameView)));
- 运行管道:pipeline.run();
这样,您就可以在运行时使用ValueProviders为SpannerIO分配表和列。请注意,上述代码仅为示例,您需要根据实际情况进行适当的修改和调整。