开始使用 Google 提供的模板

Google 提供了一组开源 Dataflow 模板。有关模板的一般信息，请参阅概览页面。首先，请使用 WordCount 模板。查看其他 Google 提供的模板：

流处理模板 - 用于连续处理数据的模板：

批处理模板 - 用于批量处理数据的模板：

实用程序模板

字数统计

WordCount 模板是一种批处理管道，它可从 Cloud Storage 读取文本，将文本行标记化为单个词，并对每个词进行词频计数。如需详细了解 WordCount，请参阅 WordCount 示例流水线。

模板参数

参数	说明
`inputFile`	Cloud Storage 输入文件的路径。
`output`	Cloud Storage 输出文件的路径和前缀。

运行 WordCount 模板

控制台

转到 Dataflow 基于模板创建作业页面。

转到“基于模板创建作业”

在作业名称字段中，输入唯一的作业名称。
可选：对于区域性端点，从下拉菜单中选择一个值。默认区域性端点为 us-central1。
如需查看可以在其中运行 Dataflow 作业的区域列表，请参阅 Dataflow 位置。
从 Dataflow 模板下拉菜单中，选择 the Word Count template。
在提供的参数字段中，输入您的参数值。
点击运行作业。

gcloud

注意：如需使用 gcloud 命令行工具运行 classic 模板，您必须拥有 Cloud SDK 138.0.0 或更高版本。

在 shell 或终端中，运行模板：

gcloud dataflow jobs run JOB_NAME \
    --gcs-location gs://dataflow-templates/latest/Word_Count \
    --region REGION_NAME \
    --parameters \
    inputFile=gs://dataflow-samples/shakespeare/kinglear.txt,\
    output=gs://BUCKET_NAME/output/my_output

替换以下内容：

JOB_NAME：您选择的唯一性作业名称
REGION_NAME：要在其中部署 Dataflow 作业的区域端点，例如 us-central1
BUCKET_NAME：Cloud Storage 存储分区的名称

API

如需使用 REST API 来运行模板，请发送 HTTP POST 请求。如需详细了解 API 及其授权范围，请参阅 projects.templates.launch。

POST https://dataflow.googleapis.com/v1b3/projects/PROJECT_ID/locations/LOCATION/templates:launch?gcsPath=gs://dataflow-templates/latest/Word_Count
{
    "jobName": "JOB_NAME",
    "parameters": {
       "inputFile" : "gs://dataflow-samples/shakespeare/kinglear.txt",
       "output": "gs://BUCKET_NAME/output/my_output"
    },
    "environment": { "zone": "us-central1-f" }
}

替换以下内容：

PROJECT_ID：您要在其中运行 Dataflow 作业的 Cloud 项目 ID
JOB_NAME：您选择的唯一性作业名称
LOCATION：要在其中部署 Dataflow 作业的区域端点，例如 us-central1
BUCKET_NAME：Cloud Storage 存储分区的名称

模板源代码

Java

在 GitHub 上查看反馈

/*
 * Copyright (C) 2016 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.cloud.teleport.templates;

import org.apache.beam.sdk.Pipeline;
import org.apache.beam.sdk.io.TextIO;
import org.apache.beam.sdk.metrics.Counter;
import org.apache.beam.sdk.metrics.Metrics;
import org.apache.beam.sdk.options.Description;
import org.apache.beam.sdk.options.PipelineOptions;
import org.apache.beam.sdk.options.PipelineOptionsFactory;
import org.apache.beam.sdk.options.ValueProvider;
import org.apache.beam.sdk.transforms.Count;
import org.apache.beam.sdk.transforms.DoFn;
import org.apache.beam.sdk.transforms.MapElements;
import org.apache.beam.sdk.transforms.PTransform;
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;

/** An template that counts words in Shakespeare. */
public class WordCount {

  static class ExtractWordsFn extends DoFn<String, String> {
    private final Counter emptyLines = Metrics.counter(ExtractWordsFn.class, "emptyLines");

    @ProcessElement
    public void processElement(ProcessContext c) {
      if (c.element().trim().isEmpty()) {
        emptyLines.inc();
      }

      // Split the line into words.
      String[] words = c.element().split("[^a-zA-Z']+");

      // Output each word encountered into the output PCollection.
      for (String word : words) {
        if (!word.isEmpty()) {
          c.output(word);
        }
      }
    }
  }

  /** A SimpleFunction that converts a Word and Count into a printable string. */
  public static class FormatAsTextFn extends SimpleFunction<KV<String, Long>, String> {
    @Override
    public String apply(KV<String, Long> input) {
      return input.getKey() + ": " + input.getValue();
    }
  }

  /**
   * A PTransform that converts a PCollection containing lines of text into a PCollection of
   * formatted word counts.
   */
  public static class CountWords
      extends PTransform<PCollection<String>, PCollection<KV<String, Long>>> {
    @Override
    public PCollection<KV<String, Long>> expand(PCollection<String> lines) {

      // Convert lines of text into individual words.
      PCollection<String> words = lines.apply(ParDo.of(new ExtractWordsFn()));

      // Count the number of times each word occurs.
      PCollection<KV<String, Long>> wordCounts = words.apply(Count.<String>perElement());

      return wordCounts;
    }
  }

  /**
   * Options supported by {@link com.google.cloud.teleport.templates.WordCount}.
   *
   * <p>Inherits standard configuration options.
   */
  public interface WordCountOptions extends PipelineOptions {
    @Description("Path of the file to read from")
    ValueProvider<String> getInputFile();

    void setInputFile(ValueProvider<String> value);

    @Description("Path of the file to write to")
    ValueProvider<String> getOutput();

    void setOutput(ValueProvider<String> value);
  }

  public static void main(String[] args) {
    WordCountOptions options =
        PipelineOptionsFactory.fromArgs(args).withValidation().as(WordCountOptions.class);
    Pipeline p = Pipeline.create(options);
    p.apply("ReadLines", TextIO.read().from(options.getInputFile()))
        .apply(new CountWords())
        .apply(MapElements.via(new FormatAsTextFn()))
        .apply("WriteCounts", TextIO.write().to(options.getOutput()));

    p.run();
  }
}