How to create a file and write content in Hadoop?

To create a file and write content in Hadoop, you can use Hadoop’s Java API. Here is a simple example code:

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

public class HadoopFileWriter {
    public static void main(String[] args) {
        try {
            // 创建Hadoop配置对象
            Configuration conf = new Configuration();
            // 获取Hadoop文件系统
            FileSystem fs = FileSystem.get(conf);
            
            // 要写入的文件路径
            String filePath = "/path/to/file.txt";
            // 创建文件
            Path file = new Path(filePath);
            
            // 如果文件已经存在，则删除
            if (fs.exists(file)) {
                fs.delete(file, true);
            }
            
            // 打开一个输出流，将内容写入文件
            FSDataOutputStream outputStream = fs.create(file);
            String content = "Hello, Hadoop!";
            outputStream.write(content.getBytes());
            
            // 关闭输出流
            outputStream.close();
            
            System.out.println("File created and content written successfully.");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

In the above code, we first create a Hadoop configuration object and a Hadoop file system object. Then, we specify the file path to create and write content to, creating a Path object. Next, we check if the file already exists, and if it does, we delete it. We then use the create() method of the file system object to create an output stream and write the content to the file. Finally, we close the output stream and print a success message.

Please note that the above code is only applicable for a standalone installation of Hadoop. If you are using a distributed mode Hadoop cluster, please ensure correct configuration and write files to the HDFS path instead of the local file system path.