**

 * @author: PrincessHug

 * @date: 2019/3/18, 17:24

 * @Blog: https://www.cnblogs.com/HelloBigTable/

 */

public class HdfsClientDemo03 {

    FileSystem fs = null;

    Configuration conf = null;

    @Before

    public void init() throws URISyntaxException, IOException, InterruptedException {

        conf = new Configuration();

        fs = FileSystem.get(new URI("hdfs://192.168.126.128:9000/"),conf,"root");

    }

    /**

     * 使用缓冲流读数据

     * @throws IOException

     */

    @Test

    public void ReadData01() throws IOException {

        FSDataInputStream in = fs.open(new Path("/words1.txt"));

        BufferedReader br = new BufferedReader(new InputStreamReader(in, "UTF-8"));

        String line = null;

        //读数据

        while ((line = br.readLine()) != null){

            System.out.println(line);

        }

        //关闭资源

        br.close();

        in.close();

        fs.close();

    }

    /**

     * 使用字节数据来接收数据

     * @throws IOException

     */

    @Test

    public void ReadData02() throws IOException {

        FSDataInputStream in = fs.open(new Path("/words1.txt"));

        byte[] bytes = new byte[1024];

        in.read(bytes);

        System.out.println(new String(bytes));

        in.close();

        fs.close();

    }

    /**

     * 读取自定义偏移量的数据

     * @throws IOException

     */

    @Test

    public void randomRead() throws IOException {

        FSDataInputStream in = fs.open(new Path("/words1.txt"));

        in.seek(10);

        byte[] bytes = new byte[1024];

        in.read(bytes);

        System.out.println(new String(bytes));

        in.close();

    }

    /**

     * 从本地文件读取数据写入hdfs文件中

     * @throws IOException

     */

    @Test

    public void writeData() throws IOException {

        FSDataOutputStream out = fs.create(new Path("/window1.txt"), false);

        FileInputStream in = new FileInputStream("G:\\潭州课堂笔记视频作业\\java\\集合.txt");

        byte[] bytes = new byte[1024];

        int read = 0;

        while ((read = in.read(bytes)) != -1){

            out.write(bytes,0,read);

        }

        in.close();

        out.close();

        fs.close();

    }

    /**

     * 向hdfs文件中写自定义的数据

     */

    @Test

    public void writeData01() throws IOException {

        FSDataOutputStream out = fs.create(new Path("/Wyh"));

        out.write("I love dilireba".getBytes());

        out.close();

        fs.close();

    }

    /**

     * 使用IOUtils的传输流方法上传文件

     * @throws IOException

     */

    @Test

    public void putFileToHdfs() throws IOException {

        //从本地文件获取数据流

        FileInputStream fis = new FileInputStream(new File("G:\\潭州课堂笔记视频作业\\java\\多线程.txt"));

        //定义输出流对象

        FSDataOutputStream fos = fs.create(new Path("/threads.txt"));

        //流的传输

        IOUtils.copyBytes(fis,fos,conf);

        //关闭流

        IOUtils.closeStream(fis);

        IOUtils.closeStream(fos);

        fs.close();

    }

    @Test

    public void getFileFromHdfs() throws IOException {

        //从hdfs文件获取输入流

        FSDataInputStream fis = fs.open(new Path("/threads.txt"));

        //定义输出流对象

        FileOutputStream fos = new FileOutputStream(new File("G:\\潭州课堂笔记视频作业\\java\\threads.txt"));

        //流的传输

        IOUtils.copyBytes(fis,fos,conf);

        //关闭流

        IOUtils.closeStream(fis);

        IOUtils.closeStream(fos);

        fs.close();

    }

}