HDFS分布式文件系统01-HDFS JAVA操作与联邦机制

org.apache.hadoop.fs

        <dependency>
              <groupId>org.apache.hadoop</groupId>
              <artifactId>hadoop-common</artifactId>
              <version>3.3.4</version>
         </dependency>
         <dependency>
              <groupId>org.apache.hadoop</groupId>
              <artifactId>hadoop-hdfs</artifactId>
              <version>3.3.4</version>
         </dependency>
                  <dependency>
              <groupId>org.apache.hadoop</groupId>
              <artifactId>hadoop-client</artifactId>
              <version>3.3.4</version>
         </dependency>
         <dependency>
              <groupId>junit</groupId>
              <artifactId>junit</artifactId>
              <version>4.13</version>
        </dependency>

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import org.junit.Before;
import org.junit.Test;

import java.io.FileNotFoundException;
import java.io.IOException;

public class hdfscurdtest1 {
    FileSystem fs = null;

    @Before
    public  void init() throws IOException {
        Configuration conf = new Configuration();
        conf.set("fs.defaultFS","hdfs://192.168.100.3:9000");
        System.setProperty("HADOOP_USER_NAME","root");
        fs = FileSystem.get(conf);
    }

    @Test
    public void testAddFileToHdfs() throws Exception{
        Path src = new Path("d:\\data\\a.txt");
        Path des = new Path("/a/a.txt");
        Path des1 = new Path("/a/b/c/a.txt");
        Path des2 = new Path("/a2/a.txt");
        Path des3 = new Path("/a.txt");
        fs.copyFromLocalFile(src,des);
        fs.copyFromLocalFile(src,des1);
        fs.copyFromLocalFile(src,des2);
        fs.copyFromLocalFile(src,des3);
        fs.close();
    }

    @Test
    public void testDownloadFileToLocal() throws IllegalArgumentException,
            IOException {
        fs.copyToLocalFile(
                new Path("/a.txt"),
                new Path("D:\\downloadFile"));
    }

    @Test
    public void testMkdirAndDeleteAndRename() throws Exception {
        fs.mkdirs(new Path("/a/b/c"));
        fs.mkdirs(new Path("/a2/b2/c2"));
        fs.rename(new Path("/a"), new Path("/a3"));
        fs.delete(new Path("/a2"), true);
    }

    @Test
    public void testListFiles() throws FileNotFoundException,
            IllegalArgumentException, IOException {
        RemoteIterator<LocatedFileStatus> listFiles =
                fs.listFiles(new Path("/a"), true);
        while (listFiles.hasNext()) {
            LocatedFileStatus fileStatus = listFiles.next();
            System.out.println("文件名：" + fileStatus.getPath().getName());
            System.out.println("文件的副本数：" + fileStatus.getReplication());
            System.out.println("文件的权限：" + fileStatus.getPermission());
            System.out.println("文件大小：" + fileStatus.getLen() + "字节");
            BlockLocation[] blockLocations =
                    fileStatus.getBlockLocations();
            for (BlockLocation bl : blockLocations) {
                String[] hosts = bl.getHosts();
                System.out.println("文件的Block所在虚拟机的主机名：");
                for (String host : hosts) {
                    System.out.println(host);
                }
            }
            System.out.println("----------------------------");
        }
    }
}