HDFS中JAVA API的使用

package com.hdfs;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

import org.apache.hadoop.conf.Configuration;
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.io.IOUtils;

public class HdfsTest {
  
  //创建新文件
  public static void createFile(String dst , byte[] contents) throws IOException{
    Configuration conf = new Configuration();
    FileSystem fs = FileSystem.get(conf);
    Path dstPath = new Path(dst); //目标路径
    //打开一个输出流
    FSDataOutputStream outputStream = fs.create(dstPath);
    outputStream.write(contents);
    outputStream.close();
    fs.close();
    System.out.println("文件创建成功！");
  }
  
  //上传本地文件
  public static void uploadFile(String src,String dst) throws IOException{
    Configuration conf = new Configuration();
    FileSystem fs = FileSystem.get(conf);
    Path srcPath = new Path(src); //原路径
    Path dstPath = new Path(dst); //目标路径
    //调用文件系统的文件复制函数,前面参数是指是否删除原文件，true为删除，默认为false
    fs.copyFromLocalFile(false,srcPath, dstPath);
    
    //打印文件路径
    System.out.println("Upload to "+conf.get("fs.default.name"));
    System.out.println("------------list files------------"+"\n");
    FileStatus [] fileStatus = fs.listStatus(dstPath);
    for (FileStatus file : fileStatus) 
    {
      System.out.println(file.getPath());
    }
    fs.close();
  }
  
  //文件重命名
  public static void rename(String oldName,String newName) throws IOException{
    Configuration conf = new Configuration();
    FileSystem fs = FileSystem.get(conf);
    Path oldPath = new Path(oldName);
    Path newPath = new Path(newName);
    boolean isok = fs.rename(oldPath, newPath);
    if(isok){
      System.out.println("rename ok!");
    }else{
      System.out.println("rename failure");
    }
    fs.close();
  }
  //删除文件
  public static void delete(String filePath) throws IOException{
    Configuration conf = new Configuration();
    FileSystem fs = FileSystem.get(conf);
    Path path = new Path(filePath);
    boolean isok = fs.deleteOnExit(path);
    if(isok){
      System.out.println("delete ok!");
    }else{
      System.out.println("delete failure");
    }
    fs.close();
  }
  
  //创建目录
  public static void mkdir(String path) throws IOException{
    Configuration conf = new Configuration();
    FileSystem fs = FileSystem.get(conf);
    Path srcPath = new Path(path);
    boolean isok = fs.mkdirs(srcPath);
    if(isok){
      System.out.println("create dir ok!");
    }else{
      System.out.println("create dir failure");
    }
    fs.close();
  }
  
  //读取文件的内容
  public static void readFile(String filePath) throws IOException{
    Configuration conf = new Configuration();
    FileSystem fs = FileSystem.get(conf);
    Path srcPath = new Path(filePath);
    InputStream in = null;
    try {
      in = fs.open(srcPath);
      IOUtils.copyBytes(in, System.out, 4096, false); //复制到标准输出流
    } finally {
      IOUtils.closeStream(in);
    }
  }
  
  
  public static void main(String[] args) throws IOException {
    //测试上传文件
    //uploadFile("D:\\c.txt", "/user/hadoop/test/");
    //测试创建文件
    /*byte[] contents = "hello world 世界你好\n".getBytes();
    createFile("/user/hadoop/test1/d.txt",contents);*/
    //测试重命名
    //rename("/user/hadoop/test/d.txt", "/user/hadoop/test/dd.txt");
    //测试删除文件
    //delete("test/dd.txt"); //使用相对路径
    //delete("test1");  //删除目录
    //测试新建目录
    //mkdir("test1");
    //测试读取文件
    readFile("test1/d.txt");
  }

}