HDFS之列出文件夹下所有内容

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.util.Progressable;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.net.URI;

/**
 * 使用Java API操作HDFS文件系统
 *
 * 关键点：
 * 1）创建Configuration
 * 2）获取FileSystem
 * 3）...就是你的HDFS API的操作
 */
public class HDFSApp {

    public static final String HDFS_PATH = "hdfs://hadoop000:8020";
    FileSystem fileSystem = null;
    Configuration configuration = null;


    @Before
    public void setUp() throws Exception {
        System.out.println("--------setUp---------");


        configuration = new Configuration();
        configuration.set("dfs.replication","1");

        /**
         * 构造一个访问指定HDFS系统的客户端对象
         * 第一个参数：HDFS的URI
         * 第二个参数：客户端指定的配置参数
         * 第三个参数：客户端的身份，说白了就是用户名
         */
        fileSystem = FileSystem.get(new URI(HDFS_PATH), configuration, "hadoop");
    }


    /**
     * 创建HDFS文件夹
     */
    @Test
    public void mkdir() throws Exception {
        fileSystem.mkdirs(new Path("/hdfsapi/test"));
    }

    /**
     * 查看HDFS内容
     */
    @Test
    public void text()throws Exception {
        FSDataInputStream in = fileSystem.open(new Path("/cdh_version.properties"));
        IOUtils.copyBytes(in, System.out, 1024);
    }

    /**
     * 创建文件
     */
    @Test
    public void create()throws Exception {
//        FSDataOutputStream out = fileSystem.create(new Path("/hdfsapi/test/a.txt"));
        FSDataOutputStream out = fileSystem.create(new Path("/hdfsapi/test/b.txt"));
        out.writeUTF("hello pk: replication 1");
        out.flush();
        out.close();
    }

    /**
     * 测试文件名更改
     * @throws Exception
     */
    @Test
    public void rename() throws Exception {
        Path oldPath = new Path("/hdfsapi/test/b.txt");
        Path newPath = new Path("/hdfsapi/test/c.txt");
        boolean result = fileSystem.rename(oldPath, newPath);
        System.out.println(result);

    }


    /**
     * 拷贝本地文件到HDFS文件系统
     */
    @Test
    public void copyFromLocalFile() throws Exception {
        Path src = new Path("/Users/rocky/data/hello.txt");
        Path dst = new Path("/hdfsapi/test/");
        fileSystem.copyFromLocalFile(src,dst);
    }

    /**
     * 拷贝大文件到HDFS文件系统：带进度
     */
    @Test
    public void copyFromLocalBigFile() throws Exception {

        InputStream in = new BufferedInputStream(new FileInputStream(new File("/Users/rocky/tmp/software/jdk-8u91-linux-x64.tar.gz")));

        FSDataOutputStream out = fileSystem.create(new Path("/hdfsapi/test/jdk.tgz"),
                new Progressable() {
                    public void progress() {
                        System.out.print(".");
                    }
                });

        IOUtils.copyBytes(in, out ,4096);

    }

    /**
     * 拷贝HDFS文件到本地：下载
     */
    @Test
    public void copyToLocalFile() throws Exception {
        Path src = new Path("/hdfsapi/test/b.txt");
        Path dst = new Path("/home/hadoop/software");
        fileSystem.copyToLocalFile(src, dst);
    }


    /**
     * 查看目标文件夹下的所有文件
     */
    @Test
    public void listFiles() throws Exception {
        FileStatus[] statuses = fileSystem.listStatus(new Path("/hdfsapi/test"));

        for(FileStatus file : statuses) {
            String isDir = file.isDirectory() ? "文件夹" : "文件";
            String permission = file.getPermission().toString();
            short replication = file.getReplication();
            long length = file.getLen();
            String path = file.getPath().toString();


            System.out.println(isDir + "\t" + permission
                    + "\t" + replication + "\t" + length
                    + "\t" + path
            );
        }

    }
     @After
    public void tearDown() {
        configuration = null;
        fileSystem = null;
        System.out.println("--------tearDown---------");
    }
}

这是运行代码的结果界面

这是真实系统下文件的内容