<dependencies>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.13.2</version>
    </dependency>
    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-common</artifactId>
        <version>3.3.4</version>
    </dependency>
    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-client</artifactId>
        <version>3.3.4</version>
    </dependency>
    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-hdfs</artifactId>
        <version>3.3.4</version>
    </dependency>
</dependencies>

public class HdfsClient {
    // 创建目录
    @Test
    public void testMkdirs() throws Exception {
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(
            new URI("hdfs://192.168.88.100:9000"),
            conf, "root"
        );
        fs.mkdirs(new Path("/test/hdfs/demo"));
        fs.close();
    }

    // 删除目录（递归）
    @Test
    public void testDelete() throws Exception {
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(
            new URI("hdfs://192.168.88.100:9000"),
            conf, "root"
        );
        fs.delete(new Path("/test/hdfs/demo"), true);
        fs.close();
    }
}

    // 普通上传
    @Test
    public void testUpload() throws Exception {
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(
            new URI("hdfs://192.168.88.100:9000"), conf, "root"
        );
        fs.copyFromLocalFile(
            new Path("D:/test.txt"),
            new Path("/test/hdfs/demo/test.txt")
        );
        fs.close();
    }

    // 参数优先级测试：代码配置 > 资源文件 > 集群默认
    @Test
    public void testUploadWithPriority() throws Exception {
        Configuration conf = new Configuration();
        conf.set("dfs.replication", "2");
        FileSystem fs = FileSystem.get(
            new URI("hdfs://192.168.88.100:9000"), conf, "root"
        );
        fs.copyFromLocalFile(
            new Path("D:/test.txt"),
            new Path("/test/hdfs/demo/priority_test.txt")
        );
        fs.close();
    }

    // IO 流方式上传
    @Test
    public void testUploadByIO() throws Exception {
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(
            new URI("hdfs://192.168.88.100:9000"), conf, "root"
        );
        FileInputStream in = new FileInputStream("D:/test.txt");
        FSDataOutputStream out = fs.create(
            new Path("/test/hdfs/demo/io_upload.txt")
        );
        IOUtils.copyBytes(in, out, conf);
        IOUtils.closeStream(in);
        IOUtils.closeStream(out);
        fs.close();
    }

    // IO 流方式下载
    @Test
    public void testDownloadByIO() throws Exception {
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(
            new URI("hdfs://192.168.88.100:9000"), conf, "root"
        );
        FSDataInputStream in = fs.open(
            new Path("/test/hdfs/demo/io_upload.txt")
        );
        FileOutputStream out = new FileOutputStream("D:/io_download.txt");
        IOUtils.copyBytes(in, out, conf);
        IOUtils.closeStream(in);
        IOUtils.closeStream(out);
        fs.close();
    }

    // 读取第一块（前 128MB）
    @Test
    public void testReadFileSeek1() throws Exception {
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(
            new URI("hdfs://192.168.88.100:9000"), conf, "root"
        );
        FSDataInputStream fis = fs.open(
            new Path("/test/hdfs/demo/test.txt")
        );
        FileOutputStream fos = new FileOutputStream("D:/test.txt.part1");
        byte[] buf = new byte[1024];
        for (int i = 0; i < 1024 * 128; i++) {
            fis.read(buf);
            fos.write(buf);
        }
        IOUtils.closeStream(fos);
        IOUtils.closeStream(fis);
        fs.close();
    }

    // 读取第二块（从 128MB 位置 seek）
    @Test
    public void testReadFileSeek2() throws Exception {
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(
            new URI("hdfs://192.168.88.100:9000"), conf, "root"
        );
        FSDataInputStream fis = fs.open(
            new Path("/test/hdfs/demo/test.txt")
        );
        FileOutputStream fos = new FileOutputStream("D:/test.txt.part2");
        fis.seek(1024 * 1024 * 128);
        IOUtils.copyBytes(fis, fos, conf);
        IOUtils.closeStream(fos);
        IOUtils.closeStream(fis);
        fs.close();
    }

    // 递归查看文件详情（含块所在主机）
    @Test
    public void testFileDetailWithBlocks() throws Exception {
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(
            new URI("hdfs://192.168.88.100:9000"), conf, "root"
        );
        RemoteIterator<LocatedFileStatus> listFiles =
            fs.listFiles(new Path("/test/hdfs/demo"), true);
        while (listFiles.hasNext()) {
            LocatedFileStatus status = listFiles.next();
            System.out.println("路径：" + status.getPath());
            System.out.println("大小：" + status.getLen() + " 字节");
            System.out.println("权限：" + status.getPermission());
            System.out.println("所有者：" + status.getOwner());

            BlockLocation[] blocks = status.getBlockLocations();
            for (BlockLocation blk : blocks) {
                System.out.println("  块偏移：" + blk.getOffset() +
                    "，长度：" + blk.getLength());
                System.out.println("  DataNode：" +
                    String.join(",", blk.getHosts()));
            }
        }
        fs.close();
    }