hdfs工具类加注释

package cn.itcast.hadoop.hdfs;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.URI;

import org.apache.commons.io.IOUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.LocatedFileStatus;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.RemoteIterator;
import org.junit.Before;
import org.junit.Test;

public class HdfsUtil {

FileSystem fs = null;

@Before
public void init() throws Exception{

//读取classpath下的xxx-site.xml 配置文件，并解析其内容，封装到conf对象中
Configuration conf = new Configuration();

//也可以在代码中对conf中的配置信息进行手动设置，会覆盖掉配置文件中的读取的值
conf.set("fs.defaultFS", "hdfs://weekend110:9000/");

//根据配置信息，去获取一个具体文件系统的客户端操作实例对象
fs = FileSystem.get(new URI("hdfs://weekend110:9000/"),conf,"hadoop");

}

/**
* 上传文件，比较底层的写法
*
* @throws Exception
*/
@Test
public void upload() throws Exception {

Configuration conf = new Configuration();
conf.set("fs.defaultFS", "hdfs://weekend110:9000/");

FileSystem fs = FileSystem.get(conf);

Path dst = new Path("hdfs://weekend110:9000/aa/qingshu.txt");

FSDataOutputStream os = fs.create(dst);

FileInputStream is = new FileInputStream("c:/qingshu.txt");

IOUtils.copy(is, os);

}

/**
* 上传文件，封装好的写法
* @throws Exception
* @throws IOException
*/
@Test
public void upload2() throws Exception, IOException{

fs.copyFromLocalFile(new Path("c:/qingshu.txt"), new Path("hdfs://weekend110:9000/aaa/bbb/ccc/qingshu2.txt"));

}

/**
* 下载文件
* @throws Exception
* @throws IllegalArgumentException
*/
@Test
public void download() throws Exception {

fs.copyToLocalFile(new Path("hdfs://weekend110:9000/aa/qingshu2.txt"), new Path("c:/qingshu2.txt"));

}

/**
* 查看文件信息
* @throws IOException
* @throws IllegalArgumentException
* @throws FileNotFoundException
*
*/
@Test
public void listFiles() throws FileNotFoundException, IllegalArgumentException, IOException {

// listFiles列出的是文件信息，而且提供递归遍历
RemoteIterator<LocatedFileStatus> files = fs.listFiles(new Path("/"), true);

while(files.hasNext()){

LocatedFileStatus file = files.next();
Path filePath = file.getPath();
String fileName = filePath.getName();
System.out.println(fileName);

}

System.out.println("---------------------------------");

//listStatus 可以列出文件和文件夹的信息，但是不提供自带的递归遍历
FileStatus[] listStatus = fs.listStatus(new Path("/"));
for(FileStatus status: listStatus){

String name = status.getPath().getName();
System.out.println(name + (status.isDirectory()?" is dir":" is file"));

}

}

/**
* 创建文件夹
* @throws Exception
* @throws IllegalArgumentException
*/
@Test
public void mkdir() throws IllegalArgumentException, Exception {

fs.mkdirs(new Path("/aaa/bbb/ccc"));

}

/**
* 删除文件或文件夹
* @throws IOException
* @throws IllegalArgumentException
*/
@Test
public void rm() throws IllegalArgumentException, IOException {

fs.delete(new Path("/aa"), true);

}

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

Configuration conf = new Configuration();
conf.set("fs.defaultFS", "hdfs://weekend110:9000/");

FileSystem fs = FileSystem.get(conf);

FSDataInputStream is = fs.open(new Path("/jdk-7u65-linux-i586.tar.gz"));

FileOutputStream os = new FileOutputStream("c:/jdk7.tgz");

IOUtils.copy(is, os);
}

}