Hadoop(一)----HDFS的API操作

HDFS文件上传

1、源代码`

@Test
public void testCopyFromLocalFile() throws IOException,InterruptedException,URISyntaxException{
	//1、获取文件系统
	Configuration configuration = new Configuration();
	configuration.set("dfs.replication","2");//副本数
	FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:9000"),configuration,"root");//写自己的hadoop机器和用户名
	//2、上传文件
	fs.copyFromLocalFile(new Path("d:/test.txt"),new Path("/test.txt")); //本地路径和hdfs路径
	//3、关闭
	fs.close();
	
	System.out.println("上传结束");
}

2、将hdfs-site.xml拷贝到项目的根目录下

HDFS文件下载

@Test
public void testCopyToLocalFile() throws IOException,InterruptedException,URISyntaxException{
	//1、获取文件系统
	Configuration configuration = new Configuration();
	FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:9000"),configuration,"root");//写自己的hadoop机器和用户名
	//2、下载文件
	fs.copyToLocalFile(false,new Path("/test.txt"),new Path("d:/test.txt"),true); 
	//3、关闭
	fs.close();
	
	System.out.println("下载结束");
}

HDFS文件夹删除

@Test
public void testDelete() throws IOException,InterruptedException,URISyntaxException{
	//1、获取文件系统
	Configuration configuration = new Configuration();
	FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:9000"),configuration,"root");/
	//2、删除文件
	fs.delete(new Path("/honglou.txt"),true);
	//3、关闭
	fs.close();
	
	System.out.println("删除结束");
}

HDFS文件名更改

@Test
public void rename() throws IOException,InterruptedException,URISyntaxException{
	//1、获取文件系统
	Configuration configuration = new Configuration();
	FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:9000"),configuration,"root");//写自己的hadoop机器和用户名
	//2、修改文件名
	fs.rename(new Path("/1.txt"),new Path("/2.txt"));
	//3、关闭
	fs.close();
}

HDFS文件详情查看

@Test
public void testListFiles() throws IOException,InterruptedException,URISyntaxException{
	//1、获取文件系统
	Configuration configuration = new Configuration();
	FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:9000"),configuration,"root");
	//2、文件详情
	RemoteIterator<LocatedFileStatus> listFiles = fs.listFiles(new Path("/"),true);

	while(listFiles.hasNext()){
	LocatedFileStatus status = listFiles.next();

	//输出详情
	//文件名称
	System.out.println(status.getPath().getName());
	//长度
	System.out.println(status.getLen());
	//权限
	System.out.println(status.getPermission());
	//分组
	System.out,println(status.getGroup());
	
	//获取存储的块信息（注意：文件夹没有block）
	BlockLocation[] blockLocations = status.getBlockLocation();
	for(BlockLocation blockLocation:blockLocations){
		//获取块存储的主机节点
		String[] hosts = blockLocation.getHosts();
		for(String host :hosts){
		System.out.println(host);
		}
	}
	System.out.println("====分割线====");
	}
	//3、关闭
	fs.close();
}

HDFS文件和文件夹判断

@Test
public void testListStatus() throws IOException,InterruptedException,URISyntaxException{
	//1、获取文件系统
	Configuration configuration = new Configuration();
	FileSystem fs = FileSystem.get(new URI("hdfs://hadoop101:9000"),configuration,"root");
	//2、判断是文件还是文件夹
	FileStatus[] fileStatus = fs.listStatus(new Path("/"));
	
	for(FileStatus fileStatus : listStatus){
		//如果是文件
		if(fileStatus.isFile()){
			System.out.println("f:"+fileStatus.getPath().getName());
		}else{
		System.out.println("d:"+fileStatus.getPath().getName());
		}
	}
	//3、关闭
	fs.close();
}