如何用java下载hdfs文件到本地

你可以使用Hadoop的FileSystem API来下载HDFS文件到本地。以下是一个简单的Java程序示例：

import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path;  import java.io.BufferedOutputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream;  public class DownloadHdfsFile {      public static void main(String[] args) {         String hdfsFilePath = "/path/to/hdfs/file";         String localFilePath = "/path/to/local/file";          Configuration conf = new Configuration();         try {             FileSystem fs = FileSystem.get(conf);             Path hdfsPath = new Path(hdfsFilePath);             InputStream inputStream = fs.open(hdfsPath);             BufferedOutputStream outputStream = new BufferedOutputStream(new FileOutputStream(localFilePath));              byte[] buffer = new byte[4096];             int bytesRead;             while ((bytesRead = inputStream.read(buffer)) > 0) {                 outputStream.write(buffer, 0, bytesRead);             }              inputStream.close();             outputStream.close();             fs.close();              System.out.println("File downloaded successfully!");         } catch (IOException e) {             e.printStackTrace();         }     } } 

在上面的示例中，你需要将hdfsFilePath和localFilePath替换为实际的HDFS文件路径和本地文件路径。然后运行程序，即可将HDFS文件下载到本地。