Hadoop Java api 操作 hdfs（二）

  package com.syh.hdfs;    import org.apache.hadoop.conf.Configuration;  import org.apache.hadoop.fs.FileSystem;  import org.apache.hadoop.fs.Path;  import org.junit.After;  import org.junit.Before;  import org.junit.Test;    import java.net.URI;    public class HDFSApp {      Configuration configuration = null;      FileSystem fileSystem = null;      // 配置路径（ip地址）      public static final String HDFS_PATH = "hdfs://192.168.207.128:8020";      // 测试（新建文件夹）      @Test      public void mkdir() throws Exception {          fileSystem.mkdirs(new Path("/emperorlawd/test"));      }        // Java 连接hdfs 需要先建立一个连接      // 测试方法执行之前要执行的操作      @Before      public void setUp() throws Exception {          System.out.println("开始建立与HDFS的连接");          configuration = new Configuration();          fileSystem = FileSystem.get(new URI(HDFS_PATH), configuration, "hadoop");      }        // 测试之后要执行的代码      @After      public void tearDown() {          configuration = null;          fileSystem = null;          System.out.println("关闭与HDFS的连接");      }  }

  // 创建文件      @Test      public void create() throws Exception {          Path path = new Path("/emperorlawd/test/hello.txt");          FSDataOutputStream outputStream = fileSystem.create(path);          outputStream.write("hello hadoop".getBytes());          outputStream.flush();          outputStream.close();      }

  // 重命名文件      @Test      public void rename() throws Exception {          Path oldPath = new Path("/emperorlawd/test/hello.txt");          Path newPath = new Path("/emperorlawd/test/rehello.txt");          fileSystem.rename(oldPath, newPath);      }

  // 查看文件      @Test      public void cat() throws Exception {          Path path = new Path("/emperorlawd/test/rehello.txt");          FSDataInputStream inputStream = fileSystem.open(path);          IOUtils.copyBytes(inputStream, System.out, 1024);          inputStream.close();      }

  // 上传文件      @Test      public void upload() throws Exception {          Path localPath = new Path("cifar-10-python.tar.gz");          Path hdfsPath = new Path("/");          fileSystem.copyFromLocalFile(localPath, hdfsPath);      }

  // 下载文件      @Test      public void download() throws Exception {          Path hdfsPath = new Path("/hadoop-2.6.0-cdh5.7.0.tar.gz");          Path localPath = new Path("./down/hadoop-2.6.0-cdh5.7.0.tar.gz");          fileSystem.copyToLocalFile(false, hdfsPath, localPath, true);      }