Hadoop学习札记-文件新增、删除
Hadoop学习笔记-文件新增、删除
版本:hadoop-0.21.0
OS:Unix(Mac OS X)
在new Path的时候,文件如果加上/则代表放入根路径,否则放入/user/name/路径下,如果hdfs中不存在此路径,则抛出父目录不存在的异常。
版本:hadoop-0.21.0
OS:Unix(Mac OS X)
package cn.com.fri.hadoop; import java.io.FileNotFoundException; import java.io.IOException; import java.net.URI; import java.util.Date; import org.apache.hadoop.fs.FSDataInputStream; import org.apache.hadoop.fs.FileContext; import org.apache.hadoop.fs.FileStatus; import org.apache.hadoop.fs.Path; import org.apache.hadoop.fs.UnsupportedFileSystemException; import org.apache.hadoop.io.IOUtils; import org.apache.hadoop.security.AccessControlException; /** * 读取文件内容以及文件信息 * @author alex * */ public class MainRead { public static void main(String[] args) throws AccessControlException, FileNotFoundException, UnsupportedFileSystemException, IOException { FileContext fc = FileContext.getFileContext(URI.create("hdfs://localhost:9000")); FSDataInputStream fsInput = fc.open(new Path("test")); IOUtils.copyBytes(fsInput, System.out, 4090,false); FileStatus status = fc.getFileStatus(new Path("test")); System.out.println("--File status---"); System.out.println(new Date(status.getAccessTime())); System.out.println(status.getPath().toUri().getPath()); double i = 1024.00; Double len = new Double(status.getLen()); len = len/i; System.out.println("File length:"+len+"kb"); System.out.println("Block size:"+status.getBlockSize()/1024/1024+"mb"); System.out.println(status.getOwner()); } }
package cn.com.fri.hadoop; import java.io.BufferedInputStream; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.net.URI; import java.util.EnumSet; import org.apache.hadoop.fs.CreateFlag; import org.apache.hadoop.fs.FSDataOutputStream; import org.apache.hadoop.fs.FileAlreadyExistsException; import org.apache.hadoop.fs.FileContext; import org.apache.hadoop.fs.ParentNotDirectoryException; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.IOUtils; import org.apache.hadoop.security.AccessControlException; /** * 创建一个文件 * @author alex * */ public class MainCreate { public static void main(String[] args) throws AccessControlException, FileAlreadyExistsException, FileNotFoundException, ParentNotDirectoryException, IOException { FileContext fc = FileContext.getFileContext(URI.create("hdfs://localhost:9000")); EnumSet<CreateFlag> es = EnumSet.noneOf(CreateFlag.class); es.add(CreateFlag.CREATE); FSDataOutputStream out = fc.create(new Path("test"), es); InputStream in = new BufferedInputStream(new FileInputStream("/Users/alex/Desktop/persons.rtf")); IOUtils.copyBytes(in, out, 4090,true); } }
在new Path的时候,文件如果加上/则代表放入根路径,否则放入/user/name/路径下,如果hdfs中不存在此路径,则抛出父目录不存在的异常。