Hadoop HDFS Tools

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package cn.buaa;import java.io.ByteArrayOutputStream;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.fs.RemoteIterator;import org.apache.hadoop.io.IOUtils;/* * @author lzxyzq * HDFS一些常用命令，可参照Hadoop API FileSystem */public class HDFSTools {    public HDFSTools(){ }    //判断某个文件是否存在hdfs文件系统中已经存在    public static boolean exists(Configuration config,String path)throws IOException{        //根据配置文件信息，形成文件系统对象        FileSystem fs = FileSystem.get(config);        return fs.exists(new Path(path)); //把文件路径转换成Path        //判断是否已经存在文件    }    //给一个文件名和内容，我们在hdfs中创建文件    public static void createFile(Configuration config,String path,byte[] buf)throws IOException{        //config-->fs-->fos-->write-->close        FileSystem fs = FileSystem.get(config);        Path path2 = new Path(path);        FSDataOutputStream fos = fs.create(path2);        fos.write(buf);        fos.close();        fs.close();    }    public static void createFile(Configuration config,String path,String info)throws IOException{        //和上面函数的区别是，上面函数传入的是buf数据，下面传入的是String        createFile(config,path,info.getBytes());    }    //把hdfs上的一个文件拷贝到hdfs上另外一个位置    public static void copyFromLocal(Configuration config,String path1,String path2)throws IOException{        FileSystem fs = FileSystem.get(config);        Path p1 = new Path(path1);        Path p2 = new Path(path2);        fs.copyFromLocalFile(true, true, p1, p2);  //delSrc, overwrite, srcs, dst        fs.close();    }    //删除hdfs上的某一个文件    public static boolean deleteFile(Configuration config,String path,boolean mark)throws IOException{        //config-->fs-->delete-->close-->返回        FileSystem fs = FileSystem.get(config);        Path p1 = new Path(path);        boolean flag = fs.delete(p1, mark);        fs.close();        return flag;    }    public static boolean deleteFile(Configuration config,String path)throws IOException{        return deleteFile(config,path,true);    }    //修改HDFS上的文件名字String-->PATH-->fs.renameFile    public static boolean renameFile(Configuration config,String path1,Strign path2){        //config-->fs-->delete-->close-->返回        FileSystem fs = FileSystem.get(config);        Path oldName = new Path(path1);        Path newName = new Path(path2);        boolean flag = fs.rename(oldName, newName);        fs.close();        return flag;    }    //创建hdfs上的一个目录    public static boolean makeDir(Configuration config,String path)throws IOException{        FileSystem fs = FileSystem.get(config);        Path name = new Path(path);        boolean flag = fs.mkdirs(name);        fs.close();        return flag;    }     public static RemoteIterator<LocatedFileStatus> listFiles(Configuration config,String path,boolean mark)throws IOException{        FileSystem fs = FileSystem.get(config);        RemoteIterator<LocatedFileStatus> r1 = fs.listFiles(new Path(path), mark);        return r1;    }    public static RemoteIterator<LocatedFileStatus> listFiles(Configuration config,String path)throws IOException{        return listFiles(config,path,false);    }    public static FileStatus[] listStatus(Configuration config, String path)throws IOException{        FileSystem fs = FileSystem.get(config);        Path path1 = new Path(path);        FileStatus status[] = fs.listStatus(path1);        fs.close();        return status;    }    //读取文件内容，返回字符串    public static String readFile(Configuration config,String path)throws IOException{        FileSystem fs = FileSystem.get(config);        String temp;        InputStream is = null;   //输入流        ByteArrayOutputStream baos = null;  //输出流        Path p = new Path(path);        try{            is =fs.open(p); //打开输入流            //输入流输出流对接            baos = new ByteArrayOutputStream(is.available());            //把输入流的内容导入到输出流中            IOUtils.copyBytes(is, baos, config);            temp = baos.toString(); //把输出流的内容转成字符串            }        finally{            //关闭输入输出流和文件系统            IOUtils.closeStream(is);            IOUtils.closeStream(baos);            fs.close();        }        return temp;    }    public static boolean createDictionary(Configuration config,String path)throws IOException{        FileSystem fs = FileSystem.get(config);        Path p = new Path(path);        boolean flag = fs.mkdirs(p);        fs.close();        return flag;    }    public static void main(String[] args) throws IOException{        Configuration config = new Configuration();        String dir = "/test";        boolean flag = exists(config,dir);        if(flag==true){            System.out.println("Sorry it's exists");        }        else{            flag = createDictionary(config,dir);            if(flag==true){                System.out.println("创建成功");            }            else{                System.out.println("创建失败");            }        }        String info = "北航！！！";        String fileName = dir+"/buaa.txt";        createFile(config,fileName,info);        System.out.println("创建文件成功");        String message = readFile(config,fileName);        System.out.println(message);        FileStatus all[] = listStatus(config,"/");        for(int i=0;i<all.length;i++){            System.out.println(all[i]);        }        FileSystem fs = FileSystem.get(config);        RemoteIterator ri = listFiles(config,"/",true);        while(ri.hasNext()){            String str = ri.next().toString();            System.out.println(str);        }        deleteFile(config,fileName);        System.out.println(fileName+"is deleted");    }}