import org.apache.hadoop.io.IOUtils;

import org.apache.hadoop.fs.FsUrlStreamHandlerFactory;

import java.io.InputStream;

import java.net.URL;

public class TestHDFS {

    public static void main(String[] args) throws Exception{

//        URL url = new URL("http://www.baidu.com");

        //URL这个类是Java的，他默认只认识HTTP协议，这里需要设置一下，让他认识HDFS协议

        URL.setURLStreamHandlerFactory(new FsUrlStreamHandlerFactory());

        //这里的地址和端口，相当与hdfs里的根目录， 然后在拼上要访问的文件在hdfs里的路径

        URL url = new URL("hdfs://192.168.0.104:9000/hello.txt");

        InputStream in = url.openStream();

        IOUtils.copyBytes(in, System.out, 4096, true);

    }

}

import org.apache.hadoop.conf.Configuration;

import org.apache.hadoop.fs.*;

import org.apache.hadoop.io.IOUtils;

import java.io.FileInputStream;

import java.util.Properties;

public class TestHDFS {

    public static void main(String[] args) throws Exception{

        Properties properties = System.getProperties();

        properties.setProperty("HADOOP_USER_NAME", "root");

        Configuration conf = new Configuration();

        conf.set("fs.defaultFS", "hdfs://192.168.0.104:9000");

        FileSystem fs = FileSystem.get(conf);

        //存在的情况下会覆盖之前的目录

        boolean success = fs.mkdirs(new Path("/xiaol"));

        System.out.println(success);

        success = fs.delete(new Path("/xiaol"), true);

        System.out.println(success);

        success = fs.exists(new Path("/xiaol"));

        System.out.println(success);

        success = fs.exists(new Path("/hello.txt"));

        System.out.println(success);

        FileStatus[] statuses = fs.listStatus(new Path("/"));

        for(FileStatus status : statuses){

            System.out.println(status.getPath());

            System.out.println(status.getPermission());

            System.out.println(status.getReplication());

        }

        //上传windows上的文件

        FSDataOutputStream fsout = fs.create(new Path("/test.data"), true);

        FileInputStream in = new FileInputStream("D:/test.txt");

        IOUtils.copyBytes(in, fsout, 4096, true);

    }

}