hdfs基本操作，上传、下载、删除

hadoop程序中对hdfs的操作必不可少，粘贴一个工具类，分享给大家。

import java.io.File;import java.io.FileInputStream;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.FSDataOutputStream;import org.apache.hadoop.fs.FileSystem;import org.apache.hadoop.fs.Path;/** * @author hadoop * */public class HdfsUtil {/** * 如果localFilePath是一个文件夹，则目标路径hdfsFilePath也会看成一个文件夹，然后把localFilePath下的所有文件，移动到 * hdfsFilePath文件夹下。如果localFilePath是一个文件，则目标路径hdfsFilePath也会被当成一个文件路径，就算在路径后面加 * 上了显式的“/”。 * @param conf * @param localFilePath * @param hdfsFilePath * @throws Exception */public static void upload(Configuration conf, String localFilePath, String hdfsFilePath) throws Exception{FileSystem fs = FileSystem.get(conf);Path localPath = new Path(localFilePath);Path dstPath = new Path(hdfsFilePath);fs.copyFromLocalFile(localPath, dstPath);}/** * 如果hdfsFilePath上一个文件夹，则会删除整个文件夹 * @param conf * @param hdfsFilePath * @throws Exception */public static void delete(Configuration conf, String hdfsFilePath) throws Exception{FileSystem fs = FileSystem.get(conf);Path dstPath = new Path(hdfsFilePath);fs.delete(dstPath, true);}/** * 从hdfs上下载文件，到本地。 * 如果hdfsFilePath是一个文件夹，则目标路径localFilePath也会看成一个文件夹，然后把hdfsFilePath下的所有文件，移动到 * localFilePath文件夹下。如果hdfsFilePath是一个文件，则目标路径localFilePath也会被当成一个文件路径，就算在路径后面加 * 上了显式的“/”。 * @param conf * @param hdfsFilePath * @param localFilePath * @throws Exception */public static void download(Configuration conf, String hdfsFilePath, String localFilePath) throws Exception{FileSystem fs = FileSystem.get(conf);Path localPath = new Path(localFilePath);Path hdfsPath = new Path(hdfsFilePath);fs.copyToLocalFile(hdfsPath, localPath);}/** * 把localFilePath文件内容追加到hdfsFilePath文件上 * @param conf * @param hdfsFilePath * @param localFilePath * @throws Exception */public static void append(Configuration conf, String hdfsFilePath, String localFilePath, boolean fromNewLine) throws Exception{FileSystem fs = FileSystem.get(conf);File localFile = new File(localFilePath);if(localFile.isDirectory()){throw new Exception("不支持文件夹的append操作");}Path hdfsPath = new Path(hdfsFilePath);FSDataOutputStream outputStream = fs.append(hdfsPath);if(fromNewLine){String newLine = "\n";outputStream.write(newLine.getBytes());}int bufferSize = 4096;byte[] buffer = new byte[bufferSize];FileInputStream inputStream = new FileInputStream(new File(localFilePath));int size = -1;while( (size = inputStream.read(buffer)) > 0){outputStream.write(buffer, 0, size);}inputStream.close();outputStream.close();}/** * @param hdfsFolder hdfs的父文件夹 * @param filePreffix 文件的前缀 * @throws Exception */public static boolean isFileExist(Configuration conf, String hdfsFolder, String filePreffix) throws Exception{boolean exist = false;Path parentPath = new Path(hdfsFolder);    FileSystem fileSystem = FileSystem.get(conf);FileStatus[] fileStatus = fileSystem.listStatus(parentPath);for(int i = 0; i < fileStatus.length; i++){String name = fileStatus[i].getPath().getName();if(name.startsWith(filePreffix)){exist = true;break;}}return exist;}/** * 在hdfs上创建一个空文件 * @param conf * @param hdfsFileName */public static void createEmptyFile(Configuration conf, String hdfsFileName) throws Exception{Path filePath = new Path(hdfsFileName);    FileSystem fileSystem = FileSystem.get(conf);    FSDataOutputStream stream = fileSystem.create(filePath);    stream.write("".getBytes());    stream.close();}/** * @param args */public static void main(String[] args) throws Exception {Configuration conf = new Configuration();conf.set("fs.default.name", Prop.FS_DEFAULT_NAME);conf.set("dfs.support.append", Prop.DFS_SUPPORT_APPEND);String localFilePath = "hadoop/test/file1";String hdfsFilePath = "/user/test/file0";HdfsUtil.upload(conf, localFilePath, hdfsFilePath);//HdfsUtil.delete(conf, hdfsFilePath);//HdfsUtil.download(conf, hdfsFilePath, localFilePath);//HdfsUtil.append(conf, hdfsFilePath, localFilePath, true);}}