向HDFS中指定的文件追加内容,由用户指定内容追加到原有文件的开头或结尾。

import java.io.FileInputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Scanner;

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

public class H_AppendorBefore {
    public static void DelFile(FileSystem fs, Path p_remotepath) {
        try {
            if (fs.delete(p_remotepath, true)) {
                ;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        
    }

    public static void appendToFileBefore(FileSystem fs, String localFilePath,
            String remoteFilePath) {
        Path remotePath = new Path(remoteFilePath);

        try {
            FileInputStream in_local = new FileInputStream(localFilePath);
            FSDataInputStream in_remote = fs.open(remotePath);
            DelFile(fs, remotePath);
            FSDataOutputStream out = fs.create(remotePath);
            out.close();
            out = fs.append(remotePath);
            byte[] data = new byte[1024];
            int read = -1;
            while ((read = in_local.read(data)) > 0) {
                out.write(data, 0, read);
            }
            while ((read = in_remote.read(data)) > 0) {
                out.write(data, 0, read);
            }
            out.close();
            System.out.println("write_before success");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void appendToFile(FileSystem fs, String localFilePath,
            String remoteFilePath) {
        Path remotePath = new Path(remoteFilePath);
        try {
            FileInputStream in = new FileInputStream(localFilePath);
            FSDataOutputStream out = fs.append(remotePath);
            byte[] data = new byte[1024];
            int read = -1;
            while ((read = in.read(data)) > 0) {
                out.write(data, 0, read);
            }
            out.close();
            System.out.println("write_append success");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        try {
            Var_init var = new Var_init();
            Scanner sc = new Scanner(System.in);
            System.out.println("input wa to write_append, wb to write_before");
            String str = sc.next();
            if (str.equals("wa")) {
                appendToFile(var.fs, var.s_localFilePath, var.s_remoteFilePath);
            } else if (str.equals("wb")) {
                appendToFileBefore(var.fs, var.s_localFilePath,
                        var.s_remoteFilePath);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

Var_init类参考 https://www.cnblogs.com/MiraculousB/p/13848744.html