eclipse插件的编译——Hadoop0.2.02版

踏雪寻梅

　　package com.kingdee.hadoop;
　　import java.io.BufferedReader;
　　import java.io.IOException;
　　import java.io.InputStream;
　　import java.io.InputStreamReader;
　　import org.apache.hadoop.conf.Configuration;
　　import  org.apache.hadoop.fs.FSDataOutputStream;
　　import org.apache.hadoop.fs.FileSystem;
　　import org.apache.hadoop.fs.Path;
　　/**
　　*
　　*  The utilities to operate file on hadoop hdfs.
　　*
　　*  @author luolihui 2011-07-18
　　*
　　*/

　　public>　　private  static final String ROOT_PATH = "hdfs:///";
　　private  static final int BUFFER_SIZE = 4096;
　　/**
　　* construct.
　　*/
　　public  DFSOperator(){}
　　/**
　　* Create a file on hdfs.The root path is /.
　　* for example: DFSOperator.createFile("/lory/test1.txt",  true);
　　* @param path  the file name to open
　　* @param overwrite if a file with this name  already exists, then if true, the file will be
　　* @return true if delete is successful else  IOException.
　　* @throws IOException
　　*/
　　public  static boolean createFile(String path, boolean overwrite) throws IOException
　　{
　　//String  uri = "hdfs://192.168.1.100:9000";
　　//FileSystem  fs1 = FileSystem.get(URI.create(uri), conf);
　　Configuration  conf = new Configuration();
　　FileSystem  fs = FileSystem.get(conf);
　　Path  f = new Path(ROOT_PATH + path);
　　fs.create(f,  overwrite);
　　fs.close();
　　return  true;
　　}
　　/**
　　* Delete a file on hdfs.The root path is /.
　　* for example: DFSOperator.deleteFile("/user/hadoop/output",  true);
　　* @param path the path to delete
　　* @param recursive  if path is a  directory and set to true, the directory is deleted else throws an exception.  In case of a file the recursive can be set to either true or false.
　　* @return true if delete is successful else IOException.
　　* @throws IOException
　　*/
　　public  static boolean deleteFile(String path, boolean recursive) throws IOException
　　{
　　//String  uri = "hdfs://192.168.1.100:9000";
　　//FileSystem  fs1 = FileSystem.get(URI.create(uri), conf);
　　Configuration  conf = new Configuration();
　　FileSystem  fs = FileSystem.get(conf);
　　Path  f = new Path(ROOT_PATH + path);
　　fs.delete(f,  recursive);
　　fs.close();
　　return  true;
　　}
　　/**
　　* Read a file to string on hadoop hdfs. From  stream to string.
　　* for example:  System.out.println(DFSOperator.readDFSFileToString("/user/hadoop/input/test3.txt"));
　　* @param path the path to read
　　* @return true if read is successful else  IOException.
　　* @throws IOException
　　*/
　　public  static String readDFSFileToString(String path) throws IOException
　　{
　　Configuration  conf = new Configuration();
　　FileSystem  fs = FileSystem.get(conf);
　　Path  f = new Path(ROOT_PATH + path);
　　InputStream  in = null;
　　String  str = null;
　　StringBuilder  sb = new StringBuilder(BUFFER_SIZE);
　　if  (fs.exists(f))
　　{
　　in  = fs.open(f);
　　BufferedReader  bf = new BufferedReader(new InputStreamReader(in));
　　while  ((str = bf.readLine()) != null)
　　{
　　sb.append(str);
　　sb.append("\n");
　　}
　　in.close();
　　bf.close();
　　fs.close();
　　return  sb.toString();
　　}
　　else
　　{
　　return  null;
　　}
　　}
　　/**
　　* Write string to a hadoop hdfs file.  
　　* for example:  DFSOperator.writeStringToDFSFile("/lory/test1.txt", "You are a  bad man.\nReally!\n");
　　* @param path the file where the string to  write in.
　　* @param string the context to write in a  file.
　　* @return true if write is successful else  IOException.
　　* @throws IOException
　　*/
　　public  static boolean writeStringToDFSFile(String path, String string) throws  IOException
　　{
　　Configuration  conf = new Configuration();
　　FileSystem  fs = FileSystem.get(conf);
　　FSDataOutputStream  os = null;
　　Path  f = new Path(ROOT_PATH + path);
　　os  = fs.create(f,true);
　　os.writeBytes(string);
　　os.close();
　　fs.close();
　　return  true;
　　}
　　public  static void main(String[] args)
　　{
　　try  {
　　DFSOperator.createFile("/lory/test1.txt",  true);
　　DFSOperator.deleteFile("/dfs_operator.txt",  true);
　　DFSOperator.writeStringToDFSFile("/lory/test1.txt",  "You are a bad man.\nReally?\n");
　　System.out.println(DFSOperator.readDFSFileToString("/lory/test1.txt"));
　　}  catch (IOException e) {
　　//  TODO Auto-generated catch block
　　e.printStackTrace();
　　}
　　System.out.println("===end===");
　　}
　　}