spark,又一个传说中的分布式实现,详情:http://spark-project.org/,
安装这里就不写了,因为网上已有中文介绍,这里主要是介绍一下入门,和hadoop一样,学习的时候,首先学习spark提供的字符统计例子:javaWordCount
原始代码如下:
import scala.Tuple2; import spark.api.java.JavaPairRDD; import spark.api.java.JavaRDD; import spark.api.java.JavaSparkContext; import spark.api.java.function.FlatMapFunction; import spark.api.java.function.Function2; import spark.api.java.function.PairFunction; import java.util.Arrays; import java.util.List; public class JavaWordCount { public static void main(String[] args) throws Exception { if (args.length < 2) { System.err.println("Usage: JavaWordCount <master> <file>"); System.exit(1); } JavaSparkContext ctx = new JavaSparkContext(args[0], "JavaWordCount", System.getenv("SPARK_HOME"), System.getenv("SPARK_EXAMPLES_JAR")); JavaRDD<String> lines = ctx.textFile(args[1], 1); JavaRDD<String> words = lines.flatMap(new FlatMapFunction<String, String>() { public Iterable<String> call(String s) { return Arrays.asList(s.split(" ")); } }); JavaPairRDD<String, Integer> ones = words.map(new PairFunction<String, String, Integer>() { public Tuple2<String, Integer> call(String s) { return new Tuple2<String, Integer>(s, 1); } }); JavaPairRDD<String, Integer> counts = ones.reduceByKey(new Function2<Integer, Integer, Integer>() { public Integer call(Integer i1, Integer i2) { return i1 + i2; } }); List<Tuple2<String, Integer>> output = counts.collect(); for (Tuple2 tuple : output) { System.out.println(tuple._1 + ": " + tuple._2); } System.exit(0); } }
运行: ./run spark/examples/JavaWordCount local input.txt
local:不解析,自己查
input.txt:文件类容
Hello World Bye World goole
运行的结果和haddoop中运行的JavaWordCount 一样
goole: 1 World: 2 Hello: 1 Bye: 1