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。

 1 import java.io.FileInputStream;
 2 import java.io.IOException;
 3 import java.text.SimpleDateFormat;
 4 import java.util.Scanner;
 5
 6 import org.apache.hadoop.conf.Configuration;
 7 import org.apache.hadoop.fs.FSDataInputStream;
 8 import org.apache.hadoop.fs.FSDataOutputStream;
 9 import org.apache.hadoop.fs.FileSystem;
10 import org.apache.hadoop.fs.Path;
11
12 public class H_AppendorBefore {
13     public static void DelFile(FileSystem fs, Path p_remotepath) {
14         try {
15             if (fs.delete(p_remotepath, true)) {
16                 ;
17             }
18         } catch (Exception e) {
19             e.printStackTrace();
20         }
21
22     }
23
24     public static void appendToFileBefore(FileSystem fs, String localFilePath,
25             String remoteFilePath) {
26         Path remotePath = new Path(remoteFilePath);
27
28         try {
29             FileInputStream in_local = new FileInputStream(localFilePath);
30             FSDataInputStream in_remote = fs.open(remotePath);
31             DelFile(fs, remotePath);
32             FSDataOutputStream out = fs.create(remotePath);
33             out.close();
34             out = fs.append(remotePath);
35             byte[] data = new byte[1024];
36             int read = -1;
37             while ((read = in_local.read(data)) > 0) {
38                 out.write(data, 0, read);
39             }
40             while ((read = in_remote.read(data)) > 0) {
41                 out.write(data, 0, read);
42             }
43             out.close();
44             System.out.println("write_before success");
45         } catch (IOException e) {
46             e.printStackTrace();
47         }
48     }
49
50     public static void appendToFile(FileSystem fs, String localFilePath,
51             String remoteFilePath) {
52         Path remotePath = new Path(remoteFilePath);
53         try {
54             FileInputStream in = new FileInputStream(localFilePath);
55             FSDataOutputStream out = fs.append(remotePath);
56             byte[] data = new byte[1024];
57             int read = -1;
58             while ((read = in.read(data)) > 0) {
59                 out.write(data, 0, read);
60             }
61             out.close();
62             System.out.println("write_append success");
63         } catch (IOException e) {
64             e.printStackTrace();
65         }
66     }
67
68     public static void main(String[] args) {
69         try {
70             Var_init var = new Var_init();
71             Scanner sc = new Scanner(System.in);
72             System.out.println("input wa to write_append, wb to write_before");
73             String str = sc.next();
74             if (str.equals("wa")) {
75                 appendToFile(var.fs, var.s_localFilePath, var.s_remoteFilePath);
76             } else if (str.equals("wb")) {
77                 appendToFileBefore(var.fs, var.s_localFilePath,
78                         var.s_remoteFilePath);
79             }
80         } catch (Exception e) {
81             e.printStackTrace();
82         }
83     }
84
85 }

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