通过Scala对HDFS的一些操作，包括创建目录，删除目录，上传文件，文件读取，删除文件，Append文件等等；

import java.io._
import java.net.URI
import java.util._

import org.apache.commons.lang3.StringUtils
import org.apache.hadoop.conf.Configuration
import org.apache.hadoop.fs._
import org.apache.zookeeper.common.IOUtils

/**
  * <Description> 通过scala操作HDFS<br>
  *
  * @author Sunny<br>
  * @taskId: <br>
  * @version 1.0<br>
  * @createDate 2018/06/11 9:29 <br>
  * @see com.spark.sunny.hdfs <br>
  */
object HDFSUtil {
  val hdfsUrl = "hdfs://iotsparkmaster:9000"
  var realUrl = ""

  /**
    * make a new dir in the hdfs
    *
    * @param dir the dir may like '/tmp/testdir'
    * @return boolean true-success, false-failed
    */
  def mkdir(dir : String) : Boolean = {
    var result = false
    if (StringUtils.isNoneBlank(dir)) {
      realUrl = hdfsUrl + dir
      val config = new Configuration()
      val fs = FileSystem.get(URI.create(realUrl), config)
      if (!fs.exists(new Path(realUrl))) {
        fs.mkdirs(new Path(realUrl))
      }
      fs.close()
      result = true
    }
    result
  }

  /**
    * delete a dir in the hdfs.
    * if dir not exists, it will throw FileNotFoundException
    *
    * @param dir the dir may like '/tmp/testdir'
    * @return boolean true-success, false-failed
    *
    */
  def deleteDir(dir : String) : Boolean = {
    var result = false
    if (StringUtils.isNoneBlank(dir)) {
      realUrl = hdfsUrl + dir
      val config = new Configuration()
      val fs = FileSystem.get(URI.create(realUrl), config)
      fs.delete(new Path(realUrl), true)
      fs.close()
      result = true
    }
    result
  }

  /**
    * list files/directories/links names under a directory, not include embed
    * objects
    *
    * @param dir a folder path may like '/tmp/testdir'
    * @return List<String> list of file names
    */
  def listAll(dir : String) : List[String] = {
    val names : List[String] = new ArrayList[String]()
    if (StringUtils.isNoneBlank(dir)) {
      realUrl = hdfsUrl + dir
      val config = new Configuration()
      val fs = FileSystem.get(URI.create(realUrl), config)
      val stats = fs.listStatus(new Path(realUrl))
      for (i <- 0 to stats.length - 1) {
        if (stats(i).isFile) {
          names.add(stats(i).getPath.toString)
        } else if (stats(i).isDirectory) {
          names.add(stats(i).getPath.toString)
        } else if (stats(i).isSymlink) {
          names.add(stats(i).getPath.toString)
        }
      }
    }
    names
  }

  /**
     * upload the local file to the hds,
     * notice that the path is full like /tmp/test.txt
     * if local file not exists, it will throw a FileNotFoundException
     *
     * @param localFile local file path, may like F:/test.txt or /usr/local/test.txt
     *
     * @param hdfsFile hdfs file path, may like /tmp/dir
     * @return boolean true-success, false-failed
     *
     **/
  def uploadLocalFile2HDFS(localFile : String, hdfsFile : String) : Boolean = {
    var result = false
    if (StringUtils.isNoneBlank(localFile) && StringUtils.isNoneBlank(hdfsFile)) {
      realUrl = hdfsUrl + hdfsFile
      val config = new Configuration()
      val hdfs = FileSystem.get(URI.create(hdfsUrl), config)
      val src = new Path(localFile)
      val dst = new Path(realUrl)
      hdfs.copyFromLocalFile(src, dst)
      hdfs.close()
      result = true
    }
     result
  }

  /**
    * create a new file in the hdfs. notice that the toCreateFilePath is the full path
    *  and write the content to the hdfs file.

    * create a new file in the hdfs.
    * if dir not exists, it will create one
    *
    * @param newFile new file path, a full path name, may like '/tmp/test.txt'
    * @param content file content
    * @return boolean true-success, false-failed
    **/
  def createNewHDFSFile(newFile : String, content : String) : Boolean = {
    var result = false
    if (StringUtils.isNoneBlank(newFile) && null != content) {
      realUrl = hdfsUrl + newFile
      val config = new Configuration()
      val hdfs = FileSystem.get(URI.create(realUrl), config)
      val os = hdfs.create(new Path(realUrl))
      os.write(content.getBytes("UTF-8"))
      os.close()
      hdfs.close()
      result = true
    }
    result
  }

  /**
    * delete the hdfs file
    *
    * @param hdfsFile a full path name, may like '/tmp/test.txt'
    * @return boolean true-success, false-failed
    */
  def deleteHDFSFile(hdfsFile : String) : Boolean = {
    var result = false
    if (StringUtils.isNoneBlank(hdfsFile)) {
      realUrl = hdfsUrl + hdfsFile
      val config = new Configuration()
      val hdfs = FileSystem.get(URI.create(realUrl), config)
      val path = new Path(realUrl)
      val isDeleted = hdfs.delete(path, true)
      hdfs.close()
      result = isDeleted
    }
    result
  }

  /**
    * read the hdfs file content
    *
    * @param hdfsFile a full path name, may like '/tmp/test.txt'
    * @return byte[] file content
    */
  def readHDFSFile(hdfsFile : String) : Array[Byte] = {
    var result =  new Array[Byte](0)
    if (StringUtils.isNoneBlank(hdfsFile)) {
      realUrl = hdfsUrl + hdfsFile
      val config = new Configuration()
      val hdfs = FileSystem.get(URI.create(realUrl), config)
      val path = new Path(realUrl)
      if (hdfs.exists(path)) {
        val inputStream = hdfs.open(path)
        val stat = hdfs.getFileStatus(path)
        val length = stat.getLen.toInt
        val buffer = new Array[Byte](length)
        inputStream.readFully(buffer)
        inputStream.close()
        hdfs.close()
        result = buffer
      }
    }
    result
  }

  /**
    * append something to file dst
    *
    * @param hdfsFile a full path name, may like '/tmp/test.txt'
    * @param content string
    * @return boolean true-success, false-failed
    */
  def append(hdfsFile : String, content : String) : Boolean = {
    var result = false
    if (StringUtils.isNoneBlank(hdfsFile) && null != content) {
      realUrl = hdfsUrl + hdfsFile
      val config = new Configuration()
      config.set("dfs.client.block.write.replace-datanode-on-failure.policy", "NEVER")
      config.set("dfs.client.block.write.replace-datanode-on-failure.enable", "true")
      val hdfs = FileSystem.get(URI.create(realUrl), config)
      val path = new Path(realUrl)
      if (hdfs.exists(path)) {
        val inputStream = new ByteArrayInputStream(content.getBytes())
        val outputStream = hdfs.append(path)
        IOUtils.copyBytes(inputStream, outputStream, 4096, true)
        outputStream.close()
        inputStream.close()
        hdfs.close()
        result = true
      }
    } else {
      HDFSUtil.createNewHDFSFile(hdfsFile, content);
      result = true
    }
    result
  }

}

测试代码如下：

/**
  * <Description> <br>
  *
  * @author Sunny<br>
  * @taskId: <br>
  * @version 1.0<br>
  * @createDate 2018/06/11 13:16 <br>
  * @see com.spark.sunny.hdfs <br>
  */
object TestHDFSUtil {
  val dir = "/iotcmp/cdr"
  val parentDir = "/iotcmp"
  val hdfsUrl = "hdfs://iotsparkmaster:9000"
  def main(args: Array[String]): Unit = {
    //testDeletedirNormal
    //testUploadLocalFile2HDFS
    //testCreateNewHDFSFileNormal
    testDeleteHDFSFile
    //testReadHDFSFile
    //testAppend
  }

  @Test
  def testMkdirNull(): Unit = {
    try{
      assertEquals(false, HDFSUtil.mkdir(null));
      assertEquals(false, HDFSUtil.mkdir(" "));
      assertEquals(false, HDFSUtil.mkdir(""));
    } catch {
      case ex : Exception => assertEquals(true, false);
    }
  }

  def testMkdirNormal(): Unit = {
    HDFSUtil.deleteDir(dir)
    var result : Boolean = HDFSUtil.mkdir(dir)
    val listFile: List[String] = HDFSUtil.listAll(parentDir)
    var existFile = false
    for (i <- 0 to listFile.size() - 1) {
      val elem = listFile.get(i)
      if(elem.equals(hdfsUrl + dir)) {
        existFile = true
      }
    }
    println(existFile)
  }

  @Test
  def testDeletedirNull(): Unit = {
    try{
      assertEquals(false, HDFSUtil.deleteDir(null));
      assertEquals(false, HDFSUtil.deleteDir(" "));
      assertEquals(false, HDFSUtil.deleteDir(""));
    } catch {
      case ex : Exception => assertEquals(true, false);
    }
  }

  def testDeletedirNormal(): Unit = {
    HDFSUtil.deleteDir(dir)
    val listFile: List[String] = HDFSUtil.listAll(parentDir)
    var existFile = false
    for (i <- 0 to listFile.size() - 1) {
      val elem = listFile.get(i)
      if(elem.equals(hdfsUrl + dir)) {
        existFile = true
      }
    }
    println(existFile)
  }

  def testUploadLocalFile2HDFS(): Unit = {
    val localFile = "C:\\Users\\yaj\\Desktop\\CDR\\USAGE_CDR_53_888_0.cdr"
    val remoteFile = dir + "/USAGE_CDR_53_888_0.cdr"
    HDFSUtil.mkdir(dir)
    HDFSUtil.deleteHDFSFile(remoteFile)
    HDFSUtil.uploadLocalFile2HDFS(localFile, remoteFile)
  }

  def testCreateNewHDFSFileNormal(): Unit = {
    val newFile = dir + "/iot.txt"
    val content = "iot file1"
    HDFSUtil.deleteHDFSFile(newFile)
    HDFSUtil.createNewHDFSFile(newFile, content)
    val result = new String(HDFSUtil.readHDFSFile(newFile))
    println(result)
  }

  def testDeleteHDFSFile(): Unit = {
    this.testCreateNewHDFSFileNormal()
    val remoteFile = dir + "/iot.txt"
    val isDeleted : Boolean = HDFSUtil.deleteHDFSFile(remoteFile)
    println(isDeleted)
  }

  def testReadHDFSFile(): Unit = {
    //this.testUploadLocalFile2HDFS()
    val remoteFile = dir + "/USAGE_CDR_53_888_0.cdr"
    val result = new String(HDFSUtil.readHDFSFile(remoteFile))
    println("USAGE_CDR_53_888_0.cdr: " + result)
  }

  def testAppend(): Unit = {
    val newFile = dir + "/iot.txt"
    val content1 = "hello iot append1 \r\n"
    val content2 = "hello iot append2 \r\n"

    HDFSUtil.deleteHDFSFile(newFile)
    HDFSUtil.createNewHDFSFile(newFile, content1)
    HDFSUtil.append(newFile, content2)
    val result = new String(HDFSUtil.readHDFSFile(newFile))
    println(result)
  }
}