在Nifi 里 把 HDFS Json 为csv 格式

import org.apache.commons.io.IOUtils
import java.nio.charset.*
import java.text.SimpleDateFormat
import groovy.json.*

def flowFile = session.get()

flowFile = session.write(flowFile, {inputStream, outStream ->

def js = IOUtils.toString(inputStream, StandardCharsets.UTF_8)
def data = new JsonSlurper().parseText( js )
def columns = data.data*.keySet().flatten().unique()

// Wrap strings in double quotes, and remove nulls
def encode = { e -> e == null ? '' : e instanceof String ? /"$e"/ : "$e" }

// Print all the column names
def columnName = columns.collect { c -> encode( c ) }.join( ',' )

// Then create all the rows
def columnData = data.data.collect { row ->
// A row at a time
columns.collect { colName -> encode( row[ colName ] ) }.join( ',' )
}.join( ' ' )

StringBuilder cd = new StringBuilder()
cd.append(columnName + " ")
cd.append(columnData)

outputStream.write(cd.toString().getBytes(StandardCharsets.UTF_8))
}as StreamCallback)

session.transfer(flowFile, REL_SUCCESS)

 

 

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