hdfs的JAVA必会操作

hdfs的必会操作

创建目录

//创建目录
    public static void mkdir(String filePath) throws URISyntaxException, IOException, InterruptedException{
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:8020"), new Configuration(), "root");
        Path path= new Path(filePath);
        fs.mkdirs(path);
        System.out.println("目录创建成功："+filePath);
        fs.close();
    }

创建文件

//创建文件
    public static void createFile(String remoteFilePath)throws URISyntaxException, IOException, InterruptedException {
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:8020"), new Configuration(), "root");
        Path remotePath = new Path(remoteFilePath);
        FSDataOutputStream outputStream = fs.create(remotePath);
        outputStream.close();
        System.out.println("文件创建成功！！"+remoteFilePath);
    }

删除文件

//删除文件
    public static void deleteFile(String filePath) throws URISyntaxException, IOException, InterruptedException{
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:8020"), new Configuration(), "root");
        Path path= new Path(filePath);
        if(fs.deleteOnExit(path)) {
            System.out.println("文件删除成功："+filePath);
        } else {
            System.out.println("文件删除失败："+filePath);
        }
        fs.close();
    }

移动文件到本地

 // 移动文件到本地
    public static void moveToLocalFile(String remoteFilePath, String localFilePath) throws IOException, InterruptedException, URISyntaxException {
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:8020"), new Configuration(), "root");
        Path remotePath = new Path(remoteFilePath);
        Path localPath = new Path(localFilePath);
        fs.moveToLocalFile(remotePath, localPath);
    }

显示文件里的内容

//显示文件内容
    public static void cat(String file)throws URISyntaxException, IOException, InterruptedException
    {
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:8020"), new Configuration(), "root");
        Path filePath = new Path(file);
        if(fs.exists(filePath)) {
            FSDataInputStream in = fs.open(filePath);
            BufferedReader br = new BufferedReader(new InputStreamReader(in));
            String content = null;
            while((content = br.readLine()) != null) {
                System.out.println(content);
            }
            br.close();
            fs.close();
        }else {
            System.out.println("file "+filePath+ "doesn't exist.");
        }
        fs.close();
    }

移动hdfs的文件

//移动hdfs中的文件
    public static void moveFile(String srcPath, String dirPath) throws URISyntaxException, IOException, InterruptedException {
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:8020"), new Configuration(), "root");
        if(fs.exists(new Path(dirPath))) {
            System.out.println("文件被占用。");
            return;
        }
        if(fs.rename(new Path(srcPath), new Path(dirPath))) {
            System.out.println("文件移动成功。");
        } else {
            System.out.println("文件移动失败。");
        }
    }

上传与下载

//将本地文件上传到hdfs
    public static void copyFromLocalFile(String localPath,String srcPath) throws URISyntaxException, IOException, InterruptedException
    {
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:8020"), new Configuration(), "root");
        fs.copyFromLocalFile(new Path(localPath),new Path(srcPath));
        System.out.println("上传成功！！！");
        fs.close();
    }

    //将hdfs的文件下载到本地
    public static void downFromHdfs(String src,String dst)throws URISyntaxException, IOException, InterruptedException
    {
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:8020"), new Configuration(), "root");
        Path dstPath=new Path(dst);
        //第一个参数为：是否删除原文件，源文件，目的文件，是否使用本地文件系统
        fs.copyToLocalFile(false,new Path(src),dstPath,true);
        fs.close();
        System.out.println("文件下载成功已存放到"+dst);
    }

追加内容到文件结尾

//追加到结尾
    public static void addContentToTail(String filePath, String content, boolean head) throws IOException, InterruptedException, URISyntaxException {
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:8020"), new Configuration(), "root");
        Path path= new Path(filePath);
        FSDataOutputStream ops = fs.append(path);
        ops.write(content.getBytes());
        if (!head) {
            System.out.println("内容以追加到结尾。");
        }
        ops.close();
        fs.close();
    }

追加本地文件内容到hdfs文件结尾

 // 追加本地文件内容到目的文件结尾
    public static void addFileToTail(String localFilePath, String remoteFilePath) throws IOException, InterruptedException, URISyntaxException{
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:8020"), new Configuration(), "root");
        Path remotePath = new Path(remoteFilePath);
        // 创建一个本地文件(需要追加的文件)读入流
        FileInputStream inps = new FileInputStream(localFilePath);
        // 创建一个文件输出留，输出的内容追加到文件末尾
        FSDataOutputStream ops = fs.append(remotePath);
        byte[] buffer = new byte[1024];
        int read = -1;
        while((read = inps.read(buffer)) > 0) {
            ops.write(buffer, 0, read);
        }
        ops.close();
        inps.close();
        fs.close();
    }

追加内容到hdfs文件开头

// 追加内容到文件开头
    public static void addContentToHead(String filePath, String content) throws IOException, InterruptedException, URISyntaxException {
        // 创建一个临时本地文件
        String localFilePath = new File("").getCanonicalPath()+"\web\text\xlf.txt" ;
        // 将要追加的文件移动到本地
        moveToLocalFile(filePath, localFilePath);
        // 创建一个新的HDFS文件（空的）
        createFile(filePath);
        appendContentToTail(content,filePath, true);
        addFileToTail(localFilePath, filePath);
        System.out.println("内容以追加到开头。");
    }

判断hdfs中文件是否存在

public  static void existandcreat(String path) throws URISyntaxException, IOException, InterruptedException {
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:8020"), new Configuration(), "root");
        Path path1=new Path(path);
        if(fs.exists(path1))
        {
            System.out.println("存在！！");
        }
        else
        {
            FSDataOutputStream ops=fs.create(path1);
            ops.close();
            fs.close();
        }
    }

递归查看目录下的文件信息

/*查看当前目录下的文件信息*/
    public static void printfile(String file)throws URISyntaxException, IOException, InterruptedException
    {
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:8020"), new Configuration(), "root");
        FileStatus[] statuses=fs.listStatus(new Path(file));
        for(FileStatus s:statuses)
        {
            System.out.println("读写权限："+s.getPermission()+"; 文件大小："+s.getBlockSize()+"; 文件路径："
                    +s.getPath()+"; 文件创建时间："+s.getModificationTime());
        }
        fs.close();
    }

    /*递归查看目录下的文件信息*/
    public static void prinfileInfo(String file)throws URISyntaxException, IOException, InterruptedException
    {
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:8020"), new Configuration(), "root");
        Path path= new Path(file);
        RemoteIterator<LocatedFileStatus> iterator = fs.listFiles(path, true);
        while(iterator.hasNext()) {
            FileStatus s = iterator.next();
            System.out.println("读写权限："+s.getPermission()+"; 文件大小："+s.getBlockSize()+"; 文件路径："
                    +s.getPath()+"; 文件创建时间："+s.getModificationTime());
        }
        fs.close();
    }