hadoop小程序---写入hdfs

hadoop小程序---写入hdfs

在eclipse中引入hadoop的核心包，我用的是hadoop-core-1.0.3.jar。

写一个测试类，很简单，就是用FileSystem类来实现，和hadoop的shell类似

注意：hadoop采用流计算，都是数据都是以字节流的形式传递的。将本地文件上传到hdfs也要读文件转成字节流再写入。

import java.net.URI;

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

public class test {

	public static void main(String[] args) throws Exception {

		byte[] buff = "hello hadoop world!\n".getBytes();

		String hadoop_path = "hdfs://master:9099/mr/test1234";

		
		Configuration conf = new Configuration();
		FileSystem fs = FileSystem.get(URI.create(hadoop_path), conf);
		Path path = new Path(hadoop_path);
		FSDataOutputStream out = fs.create(path);
		// 控制复本数量-wt
		fs.setReplication(path, (short) 1);
		out.write(buff);
		out.close();
		
	}
}