实现 HDFS 的文件操作

以下是使用Hadoop API实现HDFS文件操作的示例代码：

1. 上传文件到HDFS：

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public class HdfsFileUpload {
    public static void main(String[] args) throws Exception {
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(conf);
        
        Path localPath = new Path("/path/to/local/file.txt");
        Path hdfsPath = new Path("/path/to/hdfs/file.txt");
        
        fs.copyFromLocalFile(localPath, hdfsPath);
        
        fs.close();
    }
}

2. 从HDFS下载文件：

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public class HdfsFileDownload {
    public static void main(String[] args) throws Exception {
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(conf);
        
        Path hdfsPath = new Path("/path/to/hdfs/file.txt");
        Path localPath = new Path("/path/to/local/file.txt");
        
        fs.copyToLocalFile(hdfsPath, localPath);
        
        fs.close();
    }
}

3. 删除HDFS上的文件：

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public class HdfsFileDelete {
    public static void main(String[] args) throws Exception {
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(conf);
        
        Path hdfsPath = new Path("/path/to/hdfs/file.txt");
        
        fs.delete(hdfsPath, true);
        
        fs.close();
    }
}