dataframereader如何读取http? [英] How can dataframereader read http?

问题描述

我的开发环境:

• Intellij
• Maven
• Scala2.10.6
• win7 x64

依赖项:

 <dependencies>
    <!-- https://mvnrepository.com/artifact/org.apache.spark/spark-core_2.10 -->
    <dependency>
        <groupId>org.apache.spark</groupId>
        <artifactId>spark-core_2.10</artifactId>
        <version>2.2.0</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.apache.spark/spark-mllib_2.10 -->
    <dependency>
        <groupId>org.apache.spark</groupId>
        <artifactId>spark-mllib_2.10</artifactId>
        <version>2.2.0</version>
        <scope>provided</scope>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.apache.spark/spark-sql_2.10 -->
    <dependency>
        <groupId>org.apache.spark</groupId>
        <artifactId>spark-sql_2.10</artifactId>
        <version>2.2.0</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.scala-lang/scala-library -->
    <dependency>
        <groupId>org.scala-lang</groupId>
        <artifactId>scala-library</artifactId>
        <version>2.10.6</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.scala-lang/scala-reflect -->
    <dependency>
        <groupId>org.scala-lang</groupId>
        <artifactId>scala-reflect</artifactId>
        <version>2.10.6</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.apache.hadoop/hadoop-common -->
    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-common</artifactId>
        <version>2.7.4</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.apache.hadoop/hadoop-hdfs -->
    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-hdfs</artifactId>
        <version>2.7.4</version>
    </dependency>
</dependencies>

问题:
我想将远程csv文件读入dataframe.
我接下来尝试了:

problem :
I want read remote csv file into dataframe.
I tried next:

val weburl = "http://myurl.com/file.csv"
val tfile = spark.read.option("header","true").option("inferSchema","true").csv(weburl)

它返回下一个错误:

Exception in thread "main" java.io.IOException: No FileSystem for scheme: http

我尝试了以下互联网搜索(包括stackoverflow)

I tried next following internet searching(include stackoverflow)

val content = scala.io.Source.fromURL(weburl).mkString
val list = content.split("\n")
//...doing something to string and typecase, seperate each lows to make dataframe format.

它工作正常，但我认为加载Web源csv文件的方法更智能.
有什么方法可以让DataframeReader读取HTTP csv吗?

it works fine, but I think more smart way to loading web source csv file.
Is there any way to DataframeReader can read HTTP csv?

我认为设置SparkContext.hadoopConfiguration是一些关键，因此我尝试了Internet中的许多代码.但是它不起作用，我也不知道如何设置代码行以及代码行的每种含义.

I think setting SparkContext.hadoopConfiguration is some key, so I tried many codes in internet. but it didn't work and I don't know how to set and each meaning of code lines.

下一步是我的尝试之一，但没有用.(访问"http"时出现相同的错误消息)

Next is one of my trying and it didn't work.(same error message on accessing "http")

val sc = new SparkContext(spark_conf)
val spark = SparkSession.builder.appName("Test").getOrCreate()
val hconf = sc.hadoopConfiguration


hconf.set("fs.hdfs.impl", classOf[org.apache.hadoop.hdfs.DistributedFileSystem].getName)
hconf.set("fs.file.impl", classOf[org.apache.hadoop.fs.LocalFileSystem].getName)
hconf.set("fs.file.impl", classOf[org.apache.hadoop.fs.LocalFileSystem].getName)

设置这是关键吗?还是不?
还是DataframeReader无法直接从远程源读取?比我该怎么办?
我需要为http格式导入一些特殊的库吗?

Is setting this is key? or not?
Or DataframeReader can't read directly from remote source? than how can i do it?
I need import some special library for http format?

我想知道的事情:

有什么方法可以使dataframereader读取HTTP源吗?
无需使用自己的解析数据. (例如 ).

Is there any way to dataframereader can read HTTP source?
Without using their own parsing data. (like Best way to convert online csv to dataframe scala.)
I need to read CSV format. CSV is formal format. I think more general way to read data like dataframereader.csv("local file").

我知道这个问题水平太低了.很抱歉，我的理解水平不高.

I know this question level too low. I'm sorry for my low-level of understanding.

推荐答案

据我所知，不可能直接读取HTTP数据.您可能做的最简单的事情是使用SparkFiles下载文件，但它将数据复制给每个工作人员:

As far as I know it is not possible to read HTTP data directly. Probably the simplest thing you can do is to download file using SparkFiles, but it will duplicate data to each worker:

import org.apache.spark.SparkFiles

spark.sparkContext.addFile("http://myurl.com/file.csv")
spark.read.csv(SparkFiles.get("file.csv"))

个人而言，我只是要预先下载文件并放入分布式存储中.

Personally I'd just download the file upfront and put in a distributed storage.

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