Apache Flink - Membuat Aplikasi Flink
Pada bab ini, kita akan mempelajari cara membuat aplikasi Flink.
Buka Eclipse IDE, klik New Project dan Select Java Project.
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Berikan Nama Proyek dan klik Selesai.
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Sekarang, klik Selesai seperti yang ditunjukkan pada tangkapan layar berikut.
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Sekarang, klik kanan src dan pergi ke New >> Class.
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Beri nama kelas dan klik Selesai.
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Salin dan tempel kode di bawah ini di Editor.
import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.api.java.utils.ParameterTool;
import org.apache.flink.util.Collector;
public class WordCount {
// *************************************************************************
// PROGRAM
// *************************************************************************
public static void main(String[] args) throws Exception {
final ParameterTool params = ParameterTool.fromArgs(args);
// set up the execution environment
final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
// make parameters available in the web interface
env.getConfig().setGlobalJobParameters(params);
// get input data
DataSet<String> text = env.readTextFile(params.get("input"));
DataSet<Tuple2<String, Integer>> counts =
// split up the lines in pairs (2-tuples) containing: (word,1)
text.flatMap(new Tokenizer())
// group by the tuple field "0" and sum up tuple field "1"
.groupBy(0)
.sum(1);
// emit result
if (params.has("output")) {
counts.writeAsCsv(params.get("output"), "\n", " ");
// execute program
env.execute("WordCount Example");
} else {
System.out.println("Printing result to stdout. Use --output to specify output path.");
counts.print();
}
}
// *************************************************************************
// USER FUNCTIONS
// *************************************************************************
public static final class Tokenizer implements FlatMapFunction<String, Tuple2<String, Integer>> {
public void flatMap(String value, Collector<Tuple2<String, Integer>> out) {
// normalize and split the line
String[] tokens = value.toLowerCase().split("\\W+");
// emit the pairs
for (String token : tokens) {
if (token.length() > 0) {
out.collect(new Tuple2<>(token, 1));
}
}
}
}
}
Anda akan mendapatkan banyak kesalahan di editor, karena perpustakaan Flink perlu ditambahkan ke proyek ini.
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Klik kanan pada proyek >> Build Path >> Configure Build Path.
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Pilih tab Libraries dan klik Add External JARs.
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Pergi ke direktori lib Flink, pilih semua 4 perpustakaan dan klik OK.
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Buka tab Order and Export, pilih semua perpustakaan dan klik OK.
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Anda akan melihat bahwa kesalahan sudah tidak ada lagi.
Sekarang, mari kita ekspor aplikasi ini. Klik kanan pada proyek dan klik Ekspor.
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Pilih file JAR dan klik Next
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Berikan jalur tujuan dan klik Next
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Klik Berikutnya>
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Klik Browse, pilih kelas utama (WordCount) dan klik Selesai.
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Note - Klik OK, jika Anda mendapat peringatan.
Jalankan perintah di bawah ini. Ini selanjutnya akan menjalankan aplikasi Flink yang baru saja Anda buat.
./bin/flink run /home/ubuntu/wordcount.jar --input README.txt --output /home/ubuntu/output
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