/*没有下面的话， 会报一个错误，java.lang.IllegalArgumentException: System memory 259522560 must be at least 4.718592E8（470M）. Please use a larger heap size.这是memory不够，导致无法启动SparkContext*/ conf.set("spark.testing.memory", "2000000000"); JavaSparkContext sc = new JavaSparkContext(conf);/*下面的这种倒入的方法也行*/ // JavaRDD<String> text = sc.textFile("hdfs://localhost:9000/README.txt");/*原文件是：o1abc 45o1abc 77o1abc o1abc */ JavaRDD<String> text = sc.textFile("E://temp//input//friend.txt"); List<String> strList = text.collect();/*输出str:o1abc 45str:o1abc 77str:o1abc o1abc*/ for (String str : strList) { System.out.println("str:" + str); }/*Interface FlatMapFunction<T,R>, Iterable<R> call(T t)(注意之后的版本，返回值有所变化。)*/ JavaRDD<String> words = text.flatMap(new FlatMapFunction<String, String>() {/*List的super Interface 是java.lang.Iterable*/ public Iterable<String> call(String line) throws Exception { System.out.println("flatMap once, line is "+line ); String[] wordsArray=line.split(" "); List<String> wordsList=Arrays.asList(wordsArray); return wordsList; } }); List<String> wordsList = words.collect();/*输出flatMap once, line is o1abc 45flatMap once, line is o1abc 77flatMap once, line is o1abc o1abc 更多请见：https://blog.csdn.net/qq_44596980/article/details/93385009
