hdfs java api读入文件

使用HDFS Java API读取文件可以按照以下步骤进行：

1. 获取Hadoop配置对象和文件系统对象

Configuration conf = new Configuration();
FileSystem fs = FileSystem.get(conf);

2. 构建输入流对象

Path inputPath = new Path("/path/to/your/input/file");
FSDataInputStream inputStream = fs.open(inputPath);

3. 从输入流中读取数据

byte[] buffer = new byte[1024];
int bytesRead = 0;
while ((bytesRead = inputStream.read(buffer)) > 0) {
    // 处理数据，例如写入到输出流
}

4. 关闭输入流

inputStream.close();

完整代码示例：

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.Path;
import java.io.IOException;

public class HdfsFileReader {
    public static void main(String[] args) throws IOException {
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(conf);
        Path inputPath = new Path("/path/to/your/input/file");
        FSDataInputStream inputStream = fs.open(inputPath);
        byte[] buffer = new byte[1024];
        int bytesRead = 0;
        while ((bytesRead = inputStream.read(buffer)) > 0) {
            // 处理数据，例如写入到输出流
        }
        inputStream.close();
    }
}