将用户指定的某个本地目录中的所有文件上传到HDFS指定目录中,如果HDFS已经存在某个文件,在给出提示,由用户决定是覆盖还是添加内容到原来文件,或以另外的文件名上传。
时间: 2023-06-17 08:03:50 浏览: 57
你可以使用以下步骤来实现将本地目录中的所有文件上传到HDFS指定目录中:
1. 使用Hadoop命令行工具或者Java API创建HDFS目录,例如:
```
hadoop fs -mkdir /user/hadoop/myfiles
```
2. 使用Java API读取本地目录中的所有文件,例如:
```java
File dir = new File("/path/to/local/dir");
File[] files = dir.listFiles();
```
3. 对于每个文件,检查HDFS中是否已经存在同名文件,例如:
```java
Path hdfsPath = new Path("/user/hadoop/myfiles/" + file.getName());
FileSystem fs = FileSystem.get(new Configuration());
if (fs.exists(hdfsPath)) {
// 文件已经存在
}
```
4. 如果文件已经存在,提示用户进行操作,例如:
```java
System.out.println("File " + file.getName() + " already exists in HDFS.");
System.out.println("1. Overwrite existing file.");
System.out.println("2. Append to existing file.");
System.out.println("3. Upload file with a different name.");
Scanner scanner = new Scanner(System.in);
int choice = scanner.nextInt();
```
5. 根据用户的选择进行相应操作,例如:
- 覆盖原文件:
```java
if (choice == 1) {
fs.delete(hdfsPath, false);
fs.copyFromLocalFile(new Path(file.getPath()), hdfsPath);
}
```
- 在原文件末尾添加内容:
```java
if (choice == 2) {
FSDataOutputStream out = fs.append(hdfsPath);
FileInputStream in = new FileInputStream(file);
IOUtils.copyBytes(in, out, 4096, true);
}
```
- 以不同的文件名上传:
```java
if (choice == 3) {
String newName = scanner.next();
Path newPath = new Path("/user/hadoop/myfiles/" + newName);
fs.copyFromLocalFile(new Path(file.getPath()), newPath);
}
```
6. 如果文件不存在,直接上传文件:
```java
if (!fs.exists(hdfsPath)) {
fs.copyFromLocalFile(new Path(file.getPath()), hdfsPath);
}
```
完整的Java代码示例:
```java
import java.io.File;
import java.io.FileInputStream;
import java.util.Scanner;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
public class UploadFilesToHDFS {
public static void main(String[] args) throws Exception {
File dir = new File("/path/to/local/dir");
FileSystem fs = FileSystem.get(new Configuration());
Path hdfsDir = new Path("/user/hadoop/myfiles");
if (!fs.exists(hdfsDir)) {
fs.mkdirs(hdfsDir);
}
for (File file : dir.listFiles()) {
Path hdfsPath = new Path("/user/hadoop/myfiles/" + file.getName());
if (fs.exists(hdfsPath)) {
System.out.println("File " + file.getName() + " already exists in HDFS.");
System.out.println("1. Overwrite existing file.");
System.out.println("2. Append to existing file.");
System.out.println("3. Upload file with a different name.");
Scanner scanner = new Scanner(System.in);
int choice = scanner.nextInt();
if (choice == 1) {
fs.delete(hdfsPath, false);
fs.copyFromLocalFile(new Path(file.getPath()), hdfsPath);
} else if (choice == 2) {
FSDataOutputStream out = fs.append(hdfsPath);
FileInputStream in = new FileInputStream(file);
IOUtils.copyBytes(in, out, 4096, true);
} else if (choice == 3) {
String newName = scanner.next();
Path newPath = new Path("/user/hadoop/myfiles/" + newName);
fs.copyFromLocalFile(new Path(file.getPath()), newPath);
}
} else {
fs.copyFromLocalFile(new Path(file.getPath()), hdfsPath);
}
}
}
}
```
运行该程序时,会提示用户输入操作选项,例如:
```
File file1.txt already exists in HDFS.
1. Overwrite existing file.
2. Append to existing file.
3. Upload file with a different name.
2
File file2.txt does not exist in HDFS.
File file3.txt does not exist in HDFS.
```
根据用户的选择,程序会覆盖、追加或重命名文件并上传到HDFS中。