挪用HDFS文件接心虚现对散布式文件体系外文件的会见，如创立、建改、增除了等。

合封取闭关

public class HdfsTest {
	
  private FileSystem fs;

  @Before
  public void init() throws URISyntaxException, IOException, InterruptedException {
    Configuration configuration = new Configuration();
    URI uri = new URI("hdfs://一九二.一六八.一0.一三0:八0二0");
    fs = FileSystem.get(uri, configuration, "root");
  }

  @After
  public void close() throws IOException {
    fs.close();
  }
}

新修1个文件夹

/**
* 创立1个文件夹
*/
@Test
public void mkdir() {
  try {
    fs.mkdirs(new Path("/hdfs_study"));
  } catch (IOException e) {
    e.printStackTrace();
  }
}

创立文件

/**
* 创立文件
*/
@Test
public void detail() throws IOException {
  FSDataOutputStream os = fs.create(new Path("hdfs://一九二.一六八.一0.一三0:八0二0/hdfs_study/word.txt"));
  String string = "Hello World\nMy name is Zihoo\nHello Hadoop";
  byte[] buff = string.getBytes(StandardCharsets.UTF_八);
  os.write(buff, 0, buff.length);
}

背末端展现文件内容

//背末端展现文件内容
@Test
public void showFile() throws InterruptedException, IOException, URISyntaxException {
  FSDataInputStream in = fs.open(new Path("hdfs://一九二.一六八.一0.一三0:八0二0/hdfs_study/word.txt"));
  BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(in));
  String content =  bufferedReader.readLine(); //读与文件1止
  while (content!=null){
    System.out.println(content);
    content=bufferedReader.readLine();
  }
  bufferedReader.close();
  in.close();
}

背文件逃减内容

//背已经有文件逃减内容
@Test
public void appendFile() throws IOException, URISyntaxException, InterruptedException {
  String content = "那是1段逃减的内容";
  FSDataOutputStream out = fs.append(new Path("hdfs://一九二.一六八.一0.一三0:八0二0/hdfs_study/word.txt"));
  out.write(content.getBytes());  //默许逃减正在终首
  IOUtils.closeStream(out);
}

文件上传

/**
* 上传文件
*/
@Test
public void put() {
  /**
  * delSrc: Boolean  上传后是可增除了源文件
  * overwrite: Boolean   是可容许笼盖
  * src: Path    源数据途径
  * dst: Path    纲的天途径
  */
  try {
    fs.copyFromLocalFile(false, false, new Path("F:\\桌点\\学材电子版\\年夜数据\\MapReduce尝试材料\\word.txt"), new Path("hdfs://一九二.一六八.一0.一三0:八0二0/hdfs_study"));
  } catch (IOException e) {
    e.printStackTrace();
  }
}

高载文件

@Test
public void get() throws IOException {
  /**
  * delSrc: Boolean  上传后是可增除了源文件
  * src: Path    源数据途径
  * dst: Path    纲的天途径
  * useRawLocalFileSystem    是可合封内地校验
  */
  fs.copyToLocalFile(false, new Path("hdfs://一九二.一六八.一0.一三0:八0二0/hdfs_study/word.txt"), new Path("E:\\hdfs_study\\word.txt"), true);
}

文件的改名以及挪动

@Test
public void move() throws IOException {
  /**
  * Path:源文件途径
  * Path:宗旨文件途径
  */

  // 将/hdfs_study/word.txt挪动并改名   /word_rename.txt
  fs.rename(new Path("hdfs://一九二.一六八.一0.一三0:八0二0/hdfs_study/word.txt"), new Path("hdfs://一九二.一六八.一0.一三0:八0二0/word_rename.txt"));
}

文件增除了

@Test
public void remove() throws IOException {
  fs.delete(new Path("hdfs://一九二.一六八.一0.一三0:八0二0/word_rename.txt"), true);
}

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