我正在使用火花流进行编程,但在使用 scala 时遇到了一些问题。我正在尝试使用函数 StreamingContext.fileStream
这个函数的定义是这样的:
def fileStream[K, V, F <: InputFormat[K, V]](directory: String)(implicit arg0: ClassManifest[K], arg1: ClassManifest[V], arg2: ClassManifest[F]): DStream[(K, V)]
创建一个输入流,用于监视与 Hadoop 兼容的文件系统中的新文件,并使用给定的键值类型和输入格式读取它们。以 . 开头的文件名 被忽略。K 读取 HDFS 文件的键类型 V 读取 HDFS 文件的值类型 F 读取 HDFS 文件目录的输入格式 用于监视新文件的 HDFS 目录
我不知道如何传递 Key 和 Value 的类型。我在火花流中的代码:
val ssc = new StreamingContext(args(0), "StreamingReceiver", Seconds(1),
System.getenv("SPARK_HOME"), Seq("/home/mesos/StreamingReceiver.jar"))
// Create a NetworkInputDStream on target ip:port and count the
val lines = ssc.fileStream("/home/sequenceFile")
编写hadoop文件的Java代码:
public class MyDriver {
private static final String[] DATA = { "One, two, buckle my shoe",
"Three, four, shut the door", "Five, six, pick up sticks",
"Seven, eight, lay them straight", "Nine, ten, a big fat hen" };
public static void main(String[] args) throws IOException {
String uri = args[0];
Configuration conf = new Configuration();
FileSystem fs = FileSystem.get(URI.create(uri), conf);
Path path = new Path(uri);
IntWritable key = new IntWritable();
Text value = new Text();
SequenceFile.Writer writer = null;
try {
writer = SequenceFile.createWriter(fs, conf, path, key.getClass(),
value.getClass());
for (int i = 0; i < 100; i++) {
key.set(100 - i);
value.set(DATA[i % DATA.length]);
System.out.printf("[%s]\t%s\t%s\n", writer.getLength(), key,
value);
writer.append(key, value);
}
} finally {
IOUtils.closeStream(writer);
}
}
}