hdfs简介&hdfs-shell&hdfs-API_在linux系统中,hdfs是什么

package cn.itcast.hdfs;
 
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.URI;
 
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
import org.junit.Before;
import org.junit.Test;
 
public class HDFSDemo {
	FileSystem fs = null;
	
	@Before
	public void init() throws Exception{
		//初始化文件系统的对象，第三个参数是指定什么用户来操作
		fs = FileSystem.get(new URI("hdfs://192.168.80.101:9000"), new Configuration(),"root");
	}
	
	/**
	 * 上传文件
	 * @throws Exception
	 */
	@Test
	public void testUplaod() throws Exception{
		FileInputStream in = new FileInputStream("C:/test.log");
		FSDataOutputStream out = fs.create(new Path("/aaa.log"));
		IOUtils.copyBytes(in, out, 4096,true);
	}
	
	/**
	 * 下载文件
	 * @throws Exception
	 */
	@Test
	public void testDown() throws Exception{
		FSDataInputStream in = fs.open(new Path("/aaa.log"));
		FileOutputStream out = new FileOutputStream("c:/bbb.log");
		IOUtils.copyBytes(in, out, 4096, true);
	}
	
	/**
	 * 删除文件
	 * @throws Exception
	 */
	@Test
	public void testDel() throws Exception{
		boolean flag = fs.delete(new Path("/aaa.log"),true);
		System.out.println(flag);
		
		
	}
	
	/**
	 * 创建目录
	 * @throws Exception
	 * @throws IOException
	 */
	@Test
	public void testMKdir() throws Exception, IOException{
		boolean flag = fs.mkdirs(new Path("/d1/d2"));
		System.out.println(flag);
	}
}