HDFS是一个分布式文件系统，既然是文件系统，就可以对其中的文件进行操作，比如说新建文件夹、上传文件，重命名文件，下载文件，删除文件、列举所有文件等操作。
HDFSClient.java
package com.looc.client; import java.io.FileNotFoundException; import java.io.IOException; import org.apache.hadoop.conf.Configuration; 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 HDFSClient { private FileSystem fileSystem = null; @Before public void getFileSystem() throws IOException { // 配置参数的封装对象 // 构造函数对xxx-site.xml文件进行解析，真实项目中需要将xxx-site.xml文件加载到工程中。 Configuration configuration = new Configuration(); configuration.set("fs.defaultFS", "hdfs://looc:9000"); // 获取文件系统的客户端实例对象，根据configuration中的相关参数决定。 fileSystem = FileSystem.get(configuration); } /** * 创建文件夹 * * @throws IllegalArgumentException * @throws IOException */ @Test public void testMkdir() throws IllegalArgumentException, IOException { fileSystem.mkdirs(new Path("/a/b/c")); } /** * 上传文件 * * @throws IllegalArgumentException * @throws IOException */ @Test public void testUpload() throws IllegalArgumentException, IOException { fileSystem.copyFromLocalFile(new Path("E:\\MapReduce\\WordCount.txt"), new Path("/a/b/c")); } /** * 重命名文件 * * @throws IllegalArgumentException * @throws IOException */ @Test public void testRename() throws IllegalArgumentException, IOException { fileSystem.rename(new Path("/a/b/c/WordCount.txt"), new Path("/a/b/c/WordCount.txt.rename")); } /** * 下载文件 * * @throws IllegalArgumentException * @throws IOException */ @Test public void testDownload() throws IllegalArgumentException, IOException { fileSystem.copyToLocalFile(new Path("/a/b/c/WordCount.txt.rename"), new Path("E:\\MapReduce")); } /** * 删除文件 * * @throws IllegalArgumentException * @throws IOException */ @Test public void testRmfile() throws IllegalArgumentException, IOException { boolean result = fileSystem.delete(new Path("/a/b/c/WordCount.txt.rename"), true); System.out.println(result ? "DELETE IS SUCCESSFULLY!" : "DELETE IS FAILD!"); } /** * 列举所有文件 * * @throws FileNotFoundException * @throws IllegalArgumentException * @throws IOException */ @Test public void testListFile() throws FileNotFoundException, IllegalArgumentException, IOException { RemoteIterator<LocatedFileStatus> listFiles = fileSystem.listFiles(new Path("/"), true); while (listFiles.hasNext()) { System.out.println(listFiles.next().getPath().getName()); } } }