1.新建java工程。xia

2.导包。导入/share/hadoop/hdfs 下的hadoop-hdfs-2.7.7.jar包, /share/hadoop/hdfs/lib 下的所有包， /share/hadoop/common 下的hadoop-common-2.7.7.jar包 ，  /share/hadoop/common/lib的所有包。

package week01;import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;import org.apache.commons.io.IOUtils;
import org.apache.hadoop.conf.Configuration;
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 {/*** 上传文件  比较底层的写法* @throws IOException *//*@Testpublic void upload() throws IOException{//拿到hdfs的客户端Configuration conf = new Configuration();conf.set("fs.defaultFS", "hdfs://week01:9000");FileSystem fs = FileSystem.get(conf);//上传的地方Path  dst=new Path("hdfs://week01:9000/aa/test.txt");FSDataOutputStream os = fs.create(dst);//本地文件路径FileInputStream is = new FileInputStream("c:/test.txt");IOUtils.copy(is, os);}*/FileSystem fs = null;@Beforepublic void init() throws IOException, InterruptedException, URISyntaxException{//读取classpath中的XXX-site.xml配置文件，并解析内容，封装到conf对象中Configuration conf = new Configuration();//可以手动修改配置文件中的配置信息，会覆盖原配置文件中的信息conf.set("fs.defaultFS", "hdfs://week01:9000");//根据配置信息，获取一个具体文件系统的客户端操作实例对象//fs = FileSystem.get(conf);
//		fs = FileSystem.get(new URI("hdfs://week01:9000"), conf, "hadoop");}/*** 使用封装好的方法  * @throws IllegalArgumentException* @throws IOException*/@Testpublic void upload2() throws IllegalArgumentException, IOException{fs.copyFromLocalFile(new Path("c:/test.txt"), new Path("hdfs://week01:9000/aaa/bb/cc"));}/*** 下载文件  使用封装好的方法  * @throws Exception * @throws IllegalArgumentException */@Testpublic void download() throws Exception{fs.copyToLocalFile(new Path("hdfs://week01:9000/aa/test2.txt"), new Path("c:/test2.txt"));}/*** 查看文件信息* @throws Exception * @throws IllegalArgumentException * @throws FileNotFoundException * */@Testpublic void listFiles() throws FileNotFoundException, IllegalArgumentException, Exception{//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);}}/*** 查看文件夹* @throws IOException * @throws IllegalArgumentException * @throws FileNotFoundException */@Testpublic void listJ() throws FileNotFoundException, IllegalArgumentException, IOException{//listStatus 方法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、目录* @throws IOException * @throws IllegalArgumentException */@Testpublic void mkdir() throws IllegalArgumentException, IOException{fs.mkdirs(new Path("/aaa/bb/cc"));}/*** 删除文件或文件夹* @throws IOException * @throws IllegalArgumentException */@Testpublic void delete() throws IllegalArgumentException, IOException{fs.delete(new Path("/aa"), true);}/*** */
}