HDFS常用的文件API操作Posted on
1、常用文件API操作
package cn.luxh.app.util;import java.io.IOException;import java.text.SimpleDateFormat;import java.util.Date;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.BlockLocation;import org.apache.hadoop.fs.FSDataOutputStream;import org.apache.hadoop.fs.FileStatus;import org.apache.hadoop.fs.FileSystem;import org.apache.hadoop.fs.Path;import org.apache.hadoop.hdfs.DistributedFileSystem;import org.apache.hadoop.hdfs.protocol.DatanodeInfo;public class HDFSUtil {/*** 从本地复制文件到HDFS* @param srcFilePath* @param dstFilePath* @throws IOExceptioncopyFile2HDFS(String srcFilePath,String dstFilePath) throws IOException{Configuration conf = new Configuration();Path src = new Path(srcFilePath);Path dst = new Path(dstFilePath);FileSystem hdfs = dst.getFileSystem(conf);hdfs.copyFromLocalFile(src, dst);FileStatus[] files = hdfs.listStatus(dst);if(files!=null) {for(int i=0;i<files.length;i++) {System.out.println(“the file is:”+files[i].getPath().getName());}}else {System.out.println(“no files”);}hdfs.close();}/*** 在HDFS上创建文件* @param content* @param dstFile* @throws IOExceptioncreateFileInHDFS(String content,String dstFile) throws IOException {Configuration conf = new Configuration();Path dst = new Path(dstFile);FileSystem hdfs = null;FSDataOutputStream out = null;try {hdfs = dst.getFileSystem(conf);out = hdfs.create(dst);out.writeBytes(content);out.flush();} catch (IOException e) {e.printStackTrace();throw new IOException(e);}finally {if(hdfs != null) {hdfs.close();}if(out != null) {try {out.close();} catch (IOException e) {e.printStackTrace();}}}}/*** 重命名文件* @param originalFile* @param newFile* @throws IOExceptionrenameFileInHDFS(String originalFile,String newFile) throws IOException {Configuration conf = new Configuration();Path originalPath = new Path(originalFile);Path newPath = new Path(newFile);FileSystem hdfs = newPath.getFileSystem(conf);hdfs.rename(originalPath, newPath);hdfs.close();}/*** 获得文件的最后修改时间* @param dstFile* @throws IOExceptiongetFileLastModifyTime(String dstFile) throws IOException{Configuration conf = new Configuration();Path dstPath = new Path(dstFile);FileSystem hdfs = dstPath.getFileSystem(conf);FileStatus file = hdfs.getFileStatus(dstPath);long time = file.getModificationTime();hdfs.close();System.out.println(“the last modify time is : “+new SimpleDateFormat(“yyyy-MM-dd HH:mm:ss”).format(new Date(time)));}/*** 检查文件是否存在* @param dstFile* @throws IOExceptioncheckFileIsExists(String dstFile) throws IOException {Configuration conf = new Configuration();Path dstPath = new Path(dstFile);FileSystem hdfs = dstPath.getFileSystem(conf);boolean flag = hdfs.exists(dstPath);hdfs.close();System.out.println(“is the file exists:”+flag);}/*** 获得文件的存放位置* @param dstFile* @throws IOExceptiongetFileLocations(String dstFile) throws IOException {Configuration conf = new Configuration();Path dstPath = new Path(dstFile);FileSystem hdfs = dstPath.getFileSystem(conf);FileStatus file = hdfs.getFileStatus(dstPath);BlockLocation[] blkLocations = hdfs.getFileBlockLocations(file, 0, file.getLen());if(blkLocations != null) {int len = blkLocations.length;for(int i=0;i<len;i++) {String[] hosts = blkLocations[i].getHosts();for(String host:hosts) {System.out.println(“the location’host is : “+host);}}}hdfs.close();}/*** 删除文件* @throws IOExceptiondeleteFile(String dstFile) throws IOException {Configuration conf = new Configuration();Path dstPath = new Path(dstFile);FileSystem hdfs = dstPath.getFileSystem(conf);boolean flag = hdfs.delete(dstPath, true);System.out.println(“is deleted : “+flag);}}
2、测试
勇于接受自己的失败，告诉自己，这就是自己的现实，
