Hadoop-HDFS的增删改查_hadoop zhengshanchagai

/**
 * 
 * @author ph
 * 使用systemfile
 */
public class app2 {
        //查看hadoop的根目录下的hello文件
    public static final String HDFS_PATH = "hdfs://hadoop:9000/hello";
    
    public static final String DIR_PATH = "/DIR001";
    public static final String FILE_PATH = "/DIR001/F1";
    private static FsPermission permission;
 
    public static void main(String[] args) throws Exception {
        final FileSystem file = FileSystem.get(new URI(HDFS_PATH ), new Configuration());
        
        //创建文件夹
        //file.mkdirs(f)
        file.mkdirs(new Path(DIR_PATH));
        
        //file.mkdirs(f, permission)
        file.mkdirs(new Path("/DIR002"), permission);
        
        //file.mkdirs(fs, dir, permission)
        
        
        //上传文件
        final FSDataOutputStream out = file.create(new Path(FILE_PATH));
        final FileInputStream in = new FileInputStream("E:/Demo.py");
        IOUtils.copyBytes(in, out, 1024,true);
        
        
        //下载文件
        final FSDataInputStream in = file.open(new Path(FILE_PATH));
        IOUtils.copyBytes(in, System.out, 1024,true);
        
        //删除文件（夹）
        file.delete(new Path(DIR_PATH), true);
                //后边的boolean值是表示 递归与否（如果是删除文件夹就需要用true，问建true或false）
 
 
                //文件路径是否存在
//      boolean falg = file.exists(new Path("/DIR003/file/Demo.py"));
//      System.out.println(falg);
        
        //重命名
//      file.rename(new Path("/DIR003/Demo1.py"), new Path("/DIR003/Demo.py"));
        
        //是否是文件
//      boolean falg1 = file.isFile(new Path("/DIR003/Demo.py"));
//      System.out.println(falg1);
        
        //剪切本地文件到hdfs
//      file.moveFromLocalFile(new Path("E:/Demo.py"), new Path("/Demo.py"));
        //复制本地文件到hdfs
//      file.copyFromLocalFile(new Path("E:/Demo.py"), new Path("/Demo.py"));
 
                ...  ...
    }
}
 

方式二：FileSystem

public class app3 extends TestCase {
 
    public static String hdfsUrl = "hdfs://hadoop:9000";
    
 
    @Test
     // create HDFS folder 创建一个文件夹
    public void testHDFSMkdir() throws Exception {
        //一般url只认识http协议
        //URL.setURLStreamHandlerFactory(new FsUrlStreamHandlerFactory());//保证url也认识hdfs协议，这样就可以解析HDFS_PATH了
        
        //普通操作
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(URI.create(hdfsUrl), conf);
        Path path = new Path("/test5");
        fs.mkdirs(path);
        
        //简化
        FileSystem fs = FileSystem.get(new URI(hdfsUrl), new Configuration());
        fs.mkdirs(new Path("/dir01"));
        
    }
 
    @Test
     // create a file 创建一个文件
    public void testCreateFile() throws Exception {
        //标准操作
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(URI.create(hdfsUrl), conf);
        Path path = new Path("/test/a.txt");
        FSDataOutputStream out = fs.create(path);
        out.write("hello hadoop!".getBytes());
        
        //简单操作
        FileSystem fs = FileSystem.get(URI.create(hdfsUrl), new Configuration());
        FSDataOutputStream out = fs.create(new Path("/dir01/deom2.txt"));
        out.write("hadoop 小试牛刀！".getBytes("utf-8"));
        
    }
 
    @Test
     // rename a file 重命名
    public void testRenameFile() throws Exception { // rename a file 重命名
        //标准操作
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(URI.create(hdfsUrl), conf);
        Path path = new Path("/test/a.txt");
        Path newPath = new Path("/test/bb.txt");
        System.out.println(fs.rename(path, newPath));
        
        //简洁操作
        FileSystem fs = FileSystem.get(URI.create(hdfsUrl), new Configuration());
        System.out.print(fs.rename(new Path("/dir01/deom2.txt"), new Path("/dir01/demo03.txt")));
    }
 
    @Test
    // 上传文件
    public void testUploadLocalFile1() throws Exception { // upload a local file
        //标准操作                                                  
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(URI.create(hdfsUrl), conf);
        Path src = new Path("E:/Demo.py");
        Path dst = new Path("/test");
        fs.copyFromLocalFile(src, dst);
        
        //简洁操作
        FileSystem fs = FileSystem.get(URI.create(hdfsUrl), new Configuration());
        fs.copyFromLocalFile(new Path("E:/Demo.py"), new Path("/dir01"));
    }
 
    @Test
    //上传文件
    public void testUploadLocalFile2() throws Exception { 
        //标准书写
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(URI.create(hdfsUrl), conf);
        Path src = new Path("E:/Demo.py");
        Path dst = new Path("/test1");
        InputStream in = new BufferedInputStream(new FileInputStream(new File(
                "/home/hadoop/hadoop-1.2.1/bin/rcc")));
        FSDataOutputStream out = fs.create(new Path("/test/rcc1"));
        IOUtils.copyBytes(in, out, 4096);
        
        //简单
        FileSystem fs = FileSystem.get(URI.create(hdfsUrl), new Configuration());
        final FSDataOutputStream out = fs.create(new Path("/dir01/files"));
        final FileInputStream in = new FileInputStream("E:/Demo.py");
        IOUtils.copyBytes(in, out, 1024,true);
    }
 
    @Test
    // 列出文件
    public void testListFIles() throws Exception { // list files under folder
        //标准书写                                          
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(URI.create(hdfsUrl), conf);
        Path dst = new Path("/test");
        FileStatus[] files = fs.listStatus(dst);
        for (FileStatus file : files) {
            System.out.println(file.getPath().toString());
        }
        
        //简洁书写
        FileSystem fs = FileSystem.get(URI.create(hdfsUrl),new Configuration());
        FileStatus[] files = fs.listStatus(new Path("/dir01"));
        for (FileStatus file : files) {
            System.out.println(file.getPath().toString());
        }
    }
 
    @Test
    // 查找文件所在的数据块
    public void testGetBlockInfo() throws Exception { // list block info of file
                                                        
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(URI.create(hdfsUrl), conf);
        Path dst = new Path("/dir01/Demo.py");
        FileStatus fileStatus = fs.getFileStatus(dst);
        BlockLocation[] blkloc = fs.getFileBlockLocations(fileStatus, 0,
                fileStatus.getLen()); // 查找文件所在数据块
        for (BlockLocation loc : blkloc) {
            for (int i = 0; i < loc.getHosts().length; i++)
                System.out.println(loc.getHosts()[i]);
        }
    }
    
    
    @Test
    //删除文件、文件夹
    public void testRemoveFile () throws Exception {
        FileSystem fs = FileSystem.get(URI.create(hdfsUrl), new Configuration());
        fs.delete(new Path("/test5"), true);//是否递归删除
    }
}