【hadoop】使用javaAPI对hdfs进行文件操作

前提：1、搭建好hadoop伪分布式环境；2、安装好eclipse；

注：修改 /etc/hosts 添加 “本机IP hadoop01” ,

那么代码中创建hdfs文件系统的时候的URI hdfs://hadoop01:9000 相当于  hdfs://hadoop服务器ip（例如：192.168.1.1XX）:9000

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URI;
import java.net.URISyntaxException;

import org.apache.hadoop.conf.Configuration;
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 demo1 {

	private FileSystem fileSystem = null;
	private String location = "";

	@Before
	public void init() throws URISyntaxException, IOException {
		// 初始化文件系统,连接到hdfs的namenode，new Configuration 代表默认配置
		fileSystem = FileSystem.get(new URI("hdfs://hadoop01:9000"),
				new Configuration());
		// 下载文件的路径（文件位于电脑的绝对路径）
		location = "/data/downloads";
	}

	@Test
	public void testUpload() throws IOException {
		// Path “/” 代表 hadoop hdfs 的根路径
		String fileName = "A.tar.gz";
		InputStream in = new FileInputStream(location + fileName);
		OutputStream out = fileSystem.create(new Path("/hadoop.tar.gz"));
		IOUtils.copyBytes(in, out, 4096, true);
	}

	@Test
	public void testDownload() throws URISyntaxException, IOException {
		InputStream in = fileSystem.open(new Path("/hadoop.tar.gz"));
		String fileName = "A.tar.gz";
		OutputStream out = new FileOutputStream(location + fileName);
		IOUtils.copyBytes(in, out, 4096, true);
	}

	@Test
	public void testDel() throws IllegalArgumentException, IOException {
		// true 递归删除，用于删除文件夹
		boolean flag = fileSystem.delete(new Path("/word.text"), false);
		System.out.println(flag);
	}

}