spring - 如何使用 Spring Batch 写入 Azure Blob？

Question

我正在尝试使用 Spring Batch 将逐行 csv 写入 Azure Blob。

Autowiring Azure 存储:

@Value("${azure.storage.ConnectionString}")
private String connectionString;

@Value("${azure.storage.container.name}")
private String containerName;


@Bean
@StepScope
public FlatFileItemWriter<Pojo> writer(
        @Value("#{stepExecutionContext['marketName']}") String marketName,
        @Value("#{jobParameters['startDate']}") String startDate,
        @Value("#{jobParameters['YYYY-MM']}") String yearMonth
) {
    // Create writer instance
    FlatFileItemWriter<Pojo> writer = new FlatFileItemWriter<>();

    String fullPath = yearMonth + "/" +  marketName + "/" +
            marketName + "_" + startDate;

    BlobContainerClient container = new BlobContainerClientBuilder()
            .connectionString(connectionString)
            .containerName(containerName)
            .buildClient();

    BlobClient blob = container.getBlobClient(fullPath);

    // Set output file location
    writer.setResource((Resource) blob);

    // All job repetitions should "append" to same output file
    writer.setAppendAllowed(true);

    // Name field values sequence based on object properties
    writer.setLineAggregator(new DelimitedLineAggregator<Pojo>() {
        {
            setDelimiter(",");
            setFieldExtractor(new BeanWrapperFieldExtractor<Pojo>() {
                {
                    setNames(new String[] {
                            "market",
                            "epsg",
                            "xbin",
                            "ybin",
                            "latitude",
                            "longitude",
                            "totalDownlinkVol",
                            "totalUplinkVol"
                    });
                }
            });
        }
    });
    return writer;
}

然后我收到错误:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'scopedTarget.writer' defined in class path resource [com/example/dbreader/configuration/BatchConfig.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.item.file.FlatFileItemWriter]: Factory method 'writer' threw exception; nested exception is java.lang.ClassCastException: com.azure.storage.blob.BlobClient cannot be cast to org.springframework.core.io.Resource

Spring 提示我无法将 Blob 转换为资源。

有人知道如何在 Spring Batch Writer 中指向 Azure Blob 存储吗？

谢谢，马库斯。

Answer 1

FlatFileItemWriter 需要 org.springframework.core.io.Resource 来写入数据。如果您使用的 API 未实现此接口(interface)，则它无法与 FlatFileItemWriter 一起使用。您需要为 Azure 提供Resource 实现或查找实现它的库，例如 Azure Spring Boot Starter Storage client library for Java .