HDFS的java客户端编写

package it.cast.hdfs;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
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;

import com.sun.org.apache.xalan.internal.xsltc.compiler.sym;

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
fs=FileSystem.get(new URI("hdfs://weekend110:9000/"),conf,"hadoop");
}
/**
 * 上传文件
 * @throws IOException 
 */
@Test
public void upload() throws IOException{

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);
}
@Test
public void upload2() throws IllegalArgumentException, IOException{
fs.copyFromLocalFile(new Path("c:/qingshu.txt"), new Path("hdfs://weekend110:9000/aa/qingshu2.txt"));
}

/**
 * 下载文件
 * @throws IOException 
 * @throws IllegalArgumentException 
 */
public void download() throws IllegalArgumentException, IOException{
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> listFiles = fs.listFiles(new Path("/"), true);
    while(listFiles.hasNext()){
    LocatedFileStatus file = listFiles.next();
    Path path = file.getPath();
    String name = path.getName();
    System.out.println(name);
    }
    System.out.println("-------------------");
    //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 IOException 
 * @throws IllegalArgumentException 
 */
@Test
public void mkdir() throws IllegalArgumentException, IOException{
boolean mkdirs = fs.mkdirs(new Path("/aaa/bbb/ccc"));

}

/**
 * 删除文件或文件夹
 * @throws Exception 
 * @throws IllegalArgumentException 
 */
public void rm() throws IllegalArgumentException, Exception{
fs.delete(new Path("/aa"),true);
}

}