第一天：Java源码级实战速成（通过动手实战类、对象等，通过Spark和Hadoop案例代码和源码解析具体指知识的应用、深度详解匿名接口在Spark开发中的运用）

 

call回调

  /**    *  Return a new RDD by first applying a function to all elements of this    *  RDD, and then flattening the results.    */   def flatMap[U](f: FlatMapFunction[T, U]): JavaRDD[U] = {     import scala.collection.JavaConverters._     def fn: (T) => Iterable[U] = (x: T) => f.call(x).asScala     JavaRDD.fromRDD(rdd.flatMap(fn)(fakeClassTag[U]))(fakeClassTag[U])   }

 

 

 

/*  * Licensed to the Apache Software Foundation (ASF) under one or more  * contributor license agreements.  See the NOTICE file distributed with  * this work for additional information regarding copyright ownership.  * The ASF licenses this file to You under the Apache License, Version 2.0  * (the "License"); you may not use this file except in compliance with  * the License.  You may obtain a copy of the License at  *  *    http://www.apache.org/licenses/LICENSE-2.0  *  * Unless required by applicable law or agreed to in writing, software  * distributed under the License is distributed on an "AS IS" BASIS,  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  * See the License for the specific language governing permissions and  * limitations under the License.  */

package com.dt.spark.java.cores;

import scala.Tuple2; import scala.annotation.serializable;

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 java.util.Arrays; import java.util.List; import java.util.regex.Pattern;

public final class JavaWordCount  extends serializable{   private static final Pattern SPACE = Pattern.compile(" ");

  public static void main(String[] args) throws Exception {

  /*  if (args.length < 1) {       System.err.println("Usage: JavaWordCount ");       System.exit(1);     }*/

    SparkConf sparkConf = new SparkConf().setAppName("JavaWordCount").setMaster("local");     JavaSparkContext ctx = new JavaSparkContext(sparkConf);         //JavaRDD lines = ctx.textFile(args[0], 1);     JavaRDD lines = ctx.textFile( "G://IMFBigDataSpark2016//Bigdata_Software//spark-1.6.0-bin-hadoop2.6//spark-1.6.0-bin-hadoop2.6//spark-1.6.0-bin-hadoop2.6//README.md");       JavaRDD words = lines.flatMap(new FlatMapFunction() {       /**    *    */   private static final long serialVersionUID = 1L;

 @Override       public Iterable call(String s) {         return Arrays.asList(SPACE.split(s));       }     });

    JavaPairRDD ones = words.mapToPair(new PairFunction() {       @Override       public Tuple2 call(String s) {         return new Tuple2(s, 1);       }     });

    JavaPairRDD counts = ones.reduceByKey(new Function2() {       @Override       public Integer call(Integer i1, Integer i2) {         return i1 + i2;       }     });

    List output = counts.collect();     for (Tuple2 tuple : output) {       System.out.println(tuple._1() + ": " + tuple._2());     }     ctx.stop();   } }