spark之java代码实现wordcount

package day18test;

import org.apache.log4j.Level;

import org.apache.log4j.Logger;

import org.apache.spark.SparkConf;

import org.apache.spark.api.java.JavaPairRDD;

import org.apache.spark.api.java.JavaRDD;

import org.apache.spark.api.java.JavaSparkContext;

import org.apache.spark.api.java.function.FlatMapFunction;

import org.apache.spark.api.java.function.Function2;

import org.apache.spark.api.java.function.PairFunction;

import org.apache.spark.api.java.function.VoidFunction;

import scala.Tuple2;

import java.util.Arrays;

import java.util.Iterator;

public class WordCountJavaApp01 {

public static void main(String[] args){

//局部调整spark应用的日志级别

    Logger.getLogger("org.apache.spark").setLevel(Level.WARN);

Logger.getLogger(“org.apache.hadoop”).setLevel(Level.WARN);

Logger.getLogger(“org.spark_project”).setLevel(Level.WARN);

SparkConf conf=new SparkConf();

conf.setMaster(“local[*]”);

conf.setAppName(WordCountJavaApp01.class.getSimpleName());

JavaSparkContext jsc=new JavaSparkContext(conf);

//加载外部数据

    JavaRDD line=jsc.textFile("file:///D:/test.txt");

//打印分区数

    System.out.println("  "+line.getNumPartitions());

//flatMapfan一对多

    JavaRDD wordRDD=line.flatMap(new FlatMapFunction() {

@Override

        public Iterator call(String line)throws Exception {

//切割字符串返回迭代器对象

            return Arrays.asList(line.split("\\s+")).iterator();

}

});

JavaPairRDD pairsRDD=wordRDD.mapToPair(new PairFunction() {

@Override

        public Tuple2 call(String word)throws Exception {

return new Tuple2(word,1);

}

});

JavaPairRDD retRDD=pairsRDD.reduceByKey(new Function2() {

@Override

        public Integer call(Integer v1, Integer v2)throws Exception {

return v1+v2;

}

});

//action触发

    retRDD.foreach(new VoidFunction>() {

@Override

        public void call(Tuple2 t)throws Exception {

System.out.println(t._1+"---->"+t._2);

}

});

//释放资源

jsc.stop();

}

}

进阶
package day18test;

import org.apache.log4j.Level;

import org.apache.log4j.Logger;

import org.apache.spark.SparkConf;

import org.apache.spark.api.java.JavaPairRDD;

import org.apache.spark.api.java.JavaRDD;

import org.apache.spark.api.java.JavaSparkContext;

import scala.Tuple2;

import java.util.Arrays;

public class WordCountJavaApp2 {

public static void main(String[] args){

//局部调整spark应用的日志级别

Logger.getLogger("org.apache.spark").setLevel(Level.WARN);

Logger.getLogger(“org.apache.hadoop”).setLevel(Level.WARN);

Logger.getLogger(“org.spark_project”).setLevel(Level.WARN);

//step1加载配置问文件

SparkConf conf=new SparkConf();

conf.setAppName(WordCountJavaApp2.class.getSimpleName());

//设置分区

conf.setMaster(“local[*]”);

//创建连接对象

JavaSparkContext jsc=new JavaSparkContext(conf);

//加载外部数据

JavaRDD lines=jsc.textFile(“file:///D:/test.txt”);

//拆分字符串

JavaRDD word=lines.flatMap(line-> Arrays.asList(line.split("\\s+")).iterator());

//转化为map集合

JavaPairRDD pairRDD=word.mapToPair(words->new Tuple2(words,1));

//聚合计算每个单词出现的次数

JavaPairRDD ret=pairRDD.reduceByKey((v1,v2)->v1+v2);

//触发action

ret.foreach(t-> System.out.println(t._1+"==="+t._2));

jsc.close();

}

}