IOUtils.copyBytes可以方便地将数据写入到文件,不需要自己去控制缓冲区,也不用自己去循环读取输入源。import java.io.BufferedInputStream;
import java.io.IOException;
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 IOUtilsDemo {
public static void main(String[] args) throws IOException {
BufferedInputStream is = new BufferedInputStream(System.in);
FileSystem fs = FileSystem.get(new Configuration());
Path outputPath = new Path("hdfs://xxyy:9000" + args[0]);
FSDataOutputStream os = fs.create(outputPath);
// 参数说明
// is - 输入源
// os - 输出源
// 4096 - 缓冲区大小
// true - 是否关闭数据流,如果是false,就在finally里关掉
// IOUtils.closeStream(is);
// IOUtils.closeStream(os);
IOUtils.copyBytes(is, os, 4096, true);
System.out.println("Created file " + outputPath + " of length " +
fs.getFileStatus(outputPath).getLen() + " bytes.");
} // END: main
} // END: IOUtilsDemo
示例:
[dwapp@dw-dhw3-1 yaoyao.zhangyy]$ ls -lrth a.dat
-rw-rw-r-- 1 dwapp dwapp 485M May 13 15:58 a.dat
[dwapp@dw-dhw3-1 yaoyao.zhangyy]$ cat a.dat | java IOUtilsDemo /group/alidw/dhwdata1/ae/odl/ae01/wps11.dat
Created file hdfs://xxyy:9000/group/alidw/dhwdata1/ae/odl/ae01/wps11.dat of length 508310840 bytes.
[dwapp@dw-dhw3-1 yaoyao.zhangyy]$ hadoop fs -ls /group/alidw/dhwdata1/ae/odl/ae01/wps11.dat
Found 1 items
-rw-r--r-- 3 dwapp cug-alidw 508310840 2013-05-13 16:29 /group/alidw/dhwdata1/ae/odl/ae01/wps11.dat